Immune System Boosters

How To Bolster Your Immune System

How To Bolster Your Immune System

All Natural Immune Boosters Proven To Fight Infection, Disease And More. Discover A Natural, Safe Effective Way To Boost Your Immune System Using Ingredients From Your Kitchen Cupboard. The only common sense, no holds barred guide to hit the market today no gimmicks, no pills, just old fashioned common sense remedies to cure colds, influenza, viral infections and more.

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Immunity Crisis

Have you ever wondered WHY you get sick from different things, sometimes seemingly for no reason? Haven't you ever wished that you could find some way to stop yourself from getting sick and stay healthy all the time? Well, that might be more possible than you thought at first! Your immune system is an odd system, that many scientists are still struggling to understand. However, there have been some amazing breakthroughs! Once you get access to this detailed and helpful book, you will be able to find REAL and Applicable ways to improve your immune system and keep yourself from getting sick all of the time. This book teaches you everything that you never learned about your immune system Start learning what you can Really do to improve your immune system's health and keep your body healthier for longer! It's not hard at all Get started today!

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Evaluation of Human Immune Response

Until recently, methods for evaluating the human immune system were derived largely from experimental approaches designed to analyse deficits in host defence in specific clinical settings. With the advent of molecular approaches, immune function has been studied more directly and has led to clarification of specific pathways. As a result, the molecular basis of primary and acquired immune deficiency syndromes is better understood. In addition, the development of vaccines and the study of the natural response to infectious exposure have expanded exponentially in the wake of the HIV crisis, leading to the development of increasingly targeted methods of measuring the immune response. While assessment of the humoral immune response at the level of specific antibody is now well standardized and often routine, evaluation of the complex interactions that are needed to produce specific antibody and the idio-typic interactions that govern this remains a specialized research endeavour. The...

Vitamin C and immune function

Vitamin C is found in high concentrations in white blood cells and is rapidly utilized during infection reduced plasma concentrations are often associated with reduced immune function (see Siegel, 1993). Animal and human studies have suggested that the dietary requirements for vitamin C are increased in cancer, surgical trauma and infectious diseases (see Siegel, 1993). The belief that high intakes of vitamin C will prevent the onset of the common cold has not been substantiated scientifically, although the associated symptoms following infection appear to be reduced by a moderate intake (Coulehan et al., 1974). Rauling's claims regarding the effects of vitamin C on the common cold (Rauling, 1970) inspired a great deal of research into its effect on immune function in the 1970s and early 1980s (reviewed by Thomas and Holt, 1978 Siegel, 1993). Vitamin C deficiency in the guinea pig impairs lymphocyte proliferation, the delayed-type hypersensitivity (DTH) response to tuberculin, the...

Effect of Exogenous Glutamine on Immune Function and Survival in Animal Models of Infection and Trau

Tion) in rats following caecal ligation and puncture (Ardawi, 1991). Likewise, intravenous glutamine improved survival (92 vs. 55 in the control group) following an intraperitoneal injection of live Escherichia coli into rats (Inoue et al., 1993). Parenteral administration of alanyl-glutamine into rats improved survival (86 vs. 44 in the control group) in response to intraperitoneally infused E. coli (Naka et al., 1996). Suzuki et al. (1993) fed mice for 10 days on diets containing casein or casein supplemented with 20 g or 40 g gluta-mine kg-1 and then inoculated them intravenously with live Staphylococcus aureus. Over the following 20 days, during which the mice were maintained on the same diets they had been fed prior to infection, 80 of the control animals died, while mortality was 60 in the 20 g glutamine kg-1 group and 30 in the 40 g glutamine kg-1 group. Another study showed that inclusion of glutamine in parenteral nutrition decreased mortality to intratracheally inoculated...

EPA and DHA and innate immune function

Thus, studies in animals and humans have demonstrated that high levels of fish oil or its component n-3 PUFAs in the diet exert potent anti-inflammatory effects, particularly decreasing neutrophil and monocyte chemotaxis, superoxide production and production of pro-inflammatory cytokines. Reduced production of pro-inflammatory mediators may be beneficial in diseases characterized by excess production of these mediators (see later sections). On the other hand, these effects may compromise immune function in healthy and immune-compromised individuals. The effects of these lipids are probably dose-dependent (and disease-specific), as studies providing more modest amounts of long-chain n-3 PUFAs have not consistently demonstrated these effects on the innate immune system.

Strategies for Modulating Tissue GSH Content and Improving Immune Function

Studies using animal models of inflammation have shown that a low-protein diet will suppress glutathione synthesis, a situation that is reversed by the provision of cysteine or methionine (Hunter and Grimble, 1994, 1997). Beneficial effects on immune function, morbidity and mortality were observed in burned children when additional protein in the form of whey protein (the milk protein richest in sulphur amino acids) was fed (Alexander et al., 1980).

Boost The Immune System

Process all ingredients through a juicer, except for the olive oil, which can be stirred in with a spoon, or blended into the juice. Garlic and ginger are natural antibiotics that assist the immune system. Parsley is rich in iron to build strong red-blood corpuscles. Pear contains pectin which will stimulate a bowel movement, helping to drain the lymphatic system of toxins. Olive oil provides excellent monounsaturated fats the body needs to build strong white blood corpuscles. In my own diet, I include a habanero pepper in my immune system juice, you may want to try adding some hot pepper.

The Aging Immune System

The human immune system is a highly complex, bodywide network of specialized cells, organs, and even a separate circulatory system, which work in concert to clear infection from the body. The organs of the immune system are called lymphoid organs. Lymphatic vessels and lymph nodes comprise the special circulatory system that transports white blood cells to sites of infection throughout the body. In addition to lymph nodes (scattered in the neck, armpits, and groin areas), the tonsils, adenoids, thymus, and spleen all perform specialized immune functions. Also, bone marrow of certain long, flat bones (such as the bones of the pelvis) produces cells that grow into the more specialized cells that circulate throughout the immune system. The appendix is also a lymphoid organ and helps protect the cecal part of the colon. While immune-system processes are far too complicated for a lengthy discussion here, it is necessary to know that there are two major classes of lymphocytes B cells, which...

Probiotics and the Immune System Regulation and Stimulation

With regard to the role that the immune system plays in health maintenance and improvement, the traditional viewpoint has been one of immunity as a defence system against intrinsic (neoplasms and tumours) and extrinsic disease-causing agents (pathogens). However, this definition forms only part of the pic ture. Through control and orchestration of immune responses, the immune system is also able to regulate inflammatory events and control or limit the development of pathologies. This occurs mainly via the production of modulatory hormones (cytokines) that are able to shape and modify the character of a developing immune or inflammatory reaction (see Devereux, Chapter 1, this volume). In this context, it should be realized that gut-dwelling microbes are far from passive inhabitants of the intestinal-tract mucosa in an inert immunologi-cal sense. Paradoxically, it is the very signals generated by gastrointestinal (GI)-tract microbial interactions with the immune system that probably...

Mechanisms of the Effect of Dietary Fatty Acids on Immune Function

While it is widely recognized that dietary fatty acids can potentially alter immune and inflammatory responses, current understanding of how they act is incomplete. Several candidate mechanisms have been proposed, including alterations in membrane structure and composition, changes in membranemediated functions and signals (i.e. proteins, eicosanoids), changes in gene expression and effects on the development of the immune system (Fig. 4.3).

The gastrointestinal immune system

The first, and in normal individuals only, contact that ingested bacteria, including probiotics, have with the immune system is with the GALT. The human intestine represents the largest mass of lymphoid tissue in the body, containing over 106 lymphocytes g tissue. In addition, about 60 of the total immunoglobulin (Ig several grams) produced daily is secreted into the gastrointestinal tract. GALT is part of the mucosal immune system (i.e. gastrointestinal tract, respiratory tract, oral cavity, urogenital tract and mammary glands) and has unique cell types and mechanisms of immunity. The special nature of intestinal immunity has evolved under constant exposure to environmental antigens, whilst requiring an effective response to an invading pathogen despite the presence of dietary antigens. The difference between immune responses to dietary proteins and antigens of colonizing bacteria may play a role in the prevention of hypersensitivity reactions to food proteins. Different components...

Effects on the development of the immune system

Despite the amount of work done in healthy adults, human diseases and animal models of disease, little work has been done on the effect of dietary PUFAs on T-cell development in the infant or young animal. However, a recent study examined the effect of altered long-chain PUFA availability on the functional indices of immune development during the first 42 days of human life (Field et al., 2000). A group of clinically stable preterm infants were fed human milk, standard preterm infant formula or a preterm infant formula containing DHA (0.4 ) and arachidonic acid (0.6 ) for the first 42 days of life. Using blood samples obtained at 14 and 42 days of age, the effect of diet on some parameters of immune development was studied. Compared with standard formula, feeding long-chain PUFAs significantly increased the proportion of antigen mature (CD45RO+) CD4+ cells (by approximately 25 ), compared with non-supplemented formula-fed infants and lowered the proportion of immature (CD45RA+) CD4+...

Arginine and immune function

Arginine given in large doses has a unique effect on T-cell function. T lymphocytes are essential for wounding, and the depletion of arginine significantly impairs the wound healing response. Arginine acts as a thymotropic agent and stimulates in vitro and in vivo T-cell response. Arginine also reduces the inhibitory effect of injury and wounding on T-cell function. Supplemental dietary arginine increases thymic weight in uninjured rats and minimizes the thymic involution that occurs with injury. The gain in thymic weight is due to significant increases in the lymphocyte content of the thymic glands. In healthy humans, arginine enhances the mitogenic activity of peripheral blood lymphocytes and greatly reduces posttraumatic impairment in lymphocyte blastogenesis.14 The trophic effect that arginine exerts on the thymus results in improved host immunity. Saito et al. showed that diets containing 2 arginine of the total nonprotein calories increased survival and improved delayed...

Effects of bcaa ingestion on immune responses to exercise

Donors for glutamine synthesis, and some studies have evaluated the effectiveness of BCAA supplements during exercise to maintain the plasma glutamine concentration and modify immune responses to exercise. One recent study showed that BCAA supplementation (6 g day) for 2 to 4 weeks and a 3-g dose 30 min before a long-distance run or triathlon race prevented the 24 fall in the plasma glutamine concentration observed in the placebo group and also modified the immune response to exercise.40 These authors reported that BCAA supplementation did not affect the lymphocyte proliferative response to mitogens before exercise, but did prevent the 40 fall in lymphocyte proliferation observed after exercise in the placebo group. Furthermore, blood mononuclear cells obtained from athletes in the placebo group after exercise presented a reduction in the production of several cytokines, including tumor necrosis factor-a (TNF-a), interferon-y (IFN-y), interleukin-1 (IL-1), and IL-4, compared with...

Linoleic and alinolenic acids and innate immune function

Feeding rats or mice diets deficient in n-6 or n-3 fatty acids decreased neu-trophil chemotaxis and macrophage-mediated phagocytic and cytotoxic activity, as compared with animals fed diets containing adequate amounts of these fatty acids (for references, see Kelley and Daudu, 1993). Thus, the immunolog-ical effects of essential fatty-acid deficiencies on innate immune responses are similar to the effects of other essential nutrient deficiencies. However, again as seen with other essential nutrients, an excess of essential fatty acids can impair aspects of the innate immune response. Animal studies have reported lower natural killer cell activity following the feeding of high fat including oils rich in linoleic acid (maize, sunflower or safflower oil) or in a-linolenic acid (e.g. linseed (flaxseed) oil), when compared with feeding high-saturated-fat diets (for references, see Kelley and Daudu, 1993 Calder, 1998a, b). These data suggest that a very high intake of linoleic or...

Arginine and Immune Function Animal Studies

Stress to the body, such as trauma with fracture or haemorrhage, burn injury or major elective surgical procedures, leads to alterations in immune functions and an attenuated immune response (Faist et al., 1986). This predisposes to the development of infectious complications in the days or weeks following injury. It is estimated that, among patients who die more than 24 h after hospitalization following trauma, 75 die as a result of complications of infection and the inflammatory response (Miller et al., 1982). It is in limiting this immune dysfunction that supplemental dietary arginine appears to hold most promise (see Evoy et al., 1998).

Mechanisms of Arginine Action on Immune Function

In addition to the above alterations seen in T-cell functions, supplemental arginine also benefits the innate immune response, with increases in macrophage and natural killer cell cytotoxicity (Reynolds et al., 1988a). The link between arginine metabolism and the tumoricidal activity of macrophages was highlighted by Mills et al. (1992) in a study looking at macrophage function following intraperitoneal implantation of P815 mastocytoma in naive and pre-immunized mice. Tumour rejection was associated with elevated levels of NO production and iNOS expression in peritoneal macrophages and with a reduction in arginase activity. In contrast, during times of exponential tumour growth, arginase activity was increased, with a corresponding elevation in urea and ornithine production, while NO and citrulline production were reduced. The balance between iNOS and arginase activity in macrophages has been demonstrated in many different models and is considered to be central to the shift in...

Linoleic and alinolenic acids and acquired immune function

Essential fatty-acid deficiency is reported to decrease thymus and spleen weight and suppress cell-mediated immune responses and antibody production (for references, see Kelley and Daudu, 1993 Calder 1998a). However, a large number of studies in rats, mice, rabbits, chickens and monkeys have reported lower mitogen-stimulated lymphocyte proliferation and antibody production following the feeding of diets rich in linoleic acid (maize, sunflower or safflower oils), compared with feeding high-fat diets rich in saturated fatty acids (for references, see Kelley and Daudu, 1993 Calder, 1998a, b). These data suggest that linoleic acid has the potential to suppress acquired immune function. However, no difference in blood lymphocyte proliferation, circulating immunoglobulins or the delayed-type hypersensitivity response was seen in volunteers consuming low-fat diets (25 energy as fat) that were rich (12.9 of energy) or poor (3.5 of energy) in linoleic acid (Kelley et al., 1989, 1992)....

The basic mechanisms of immune response to dietary antigen

Show a recognizable gastrointestinal tract.118 There is much current interest on the links between innate and adaptive immune responses, in particular pattern receptor molecules such as toll-like receptors and nod proteins that induce an immune response within innate cells, such as dendritic cells, that polarize subsequent T-cell responses.119,120 Evidence that oral tolerance cannot be established normally in germ-free mice suggests that the normal flora plays an important role in the generation of tolorogenic lymphocytes and the prevention of food allergies.121,122 The potential role for probiotics in prevention of food allergies in susceptible infants is thus likely to be based on the role of luminal bacteria in inducing a tolerant lymphocyte response.8,9 Transgenic mice whose only T cells responded to ovalbumin were in fact entirely tolerant of ovalbumin feeds, unless innate immune responses to the flora were blocked using cyclo-oxygenase-2 antagonists, when food-sensitive...

Taurine and Immune Function

Taurine, along with sulphate, can be regarded as a biochemical end-product of cysteine metabolism. However, it is apparent that taurine also plays a role in immune function. It is the most abundant free nitrogenous compound (often incorrectly classified as an amino acid) in cells. It is a membrane stabilizer and regulates calcium flux, thereby controlling cell stability. It has been shown to possess antioxidant properties and to regulate the release of pro-inflammatory cytokines in hamsters, rats and humans (Grimble, 1994 Huxtable, 1996 Kontny et al., 2000). The possibility that taurine might have immunomodulatory properties was indicated in studies in obligate carnivores, such as cats, in which taurine is an essential nutrient, due to an inability to synthesize the compound. Premature infants have similar metabolic difficulties. In cats deprived of taurine, substantial impairment of immune function occurs (Grimble, 1994). A large decline in lymphocytes, an increase in mononuclear...

Mechanism of the Effect of Oxidants and Antioxidants on Inflammation and Immune Function

Otz Glutathione

The oxidant molecules produced by the immune system to kill invading organisms may activate at least two important families of proteins that are sensitive to changes in cellular redox state. The families are nuclear transcription factor kappa B (NFkB) and activator protein 1 (API). These transcription factors act as 'control switches' for biological processes, not all of which are of advantage to the individual. NFkB is present in the cytosol in an inactive form, by virtue of being bound to IkB. Phosphorylation and dissociation of IkB renders the remaining NFkB dimer active. Activation of NFkB can be brought about by a wide range of stimuli, including pro-inflammatory cytokines, hydrogen peroxide, mitogens, bacteria and viruses and their related products, and UV and ionizing radiations. The dissociated IkB is degraded and the active NFkB is translocated to the nucleus, where it binds to response elements in the promoter regions of genes. A similar translocation of AP1, a transcription...

Vitamin E and immune function

One application of the effects of vitamin E on immune function is in the elderly. This has been investigated in both murine models and human trials. Adding vitamin E to the diet of aged mice increased lymphocyte proliferation, IL-2 production and the DTH response (Meydani et al., 1986). A high level of vitamin E in the diet (500 mg kg-1 food) also increased NK-cell activity of spleen cells from old (but not young) mice (Meydani et al., 1988). In another study, young and old mice were fed diets containing adequate (30 mg kg-1 diet) or high (500 mg kg-1 diet) levels of vitamin E for 6 weeks and infected with influenza A virus young mice and old mice fed the high level of vitamin E had lower lung titres of virus than old mice fed the adequate vitamin E diet (Hayek et al., 1997). The high level of vitamin E caused increased production of IL-2 and IFN-7 by spleen lymphocytes from influenza-infected old mice (Han et al., 1998 Han and Meydani, 2000). Supplementation of the diet of elderly...

Effects of selenium on the skin immune system

The skin is the frontier of the immune system, the interface of the body with the external environment and the site of exposure of the immune system to muta-genic and oxidative damage from UV radiation (reviewed in Duthie ei al., 1999). Oxidizing agents are also produced by commensal microorganisms that reside on the skin. Se has been shown to have a vital role in protecting the skin from carcinogenesis and from oxidative damage (reviewed in McKenzie, 2000). In mice, dietary Se supplements or even topical application of Se significantly decrease the incidence of skin tumours, tumour size and mortality. Mice on Se-deficient diets also have significantly lower numbers of Langerhans cells in the skin, which may result from increased secretion of TNF-a, which triggers emigration of these dendritic cells. In humans, low Se intake has been correlated with increased incidence of skin cancer, but it is not clear yet whether Se supplements protect humans from skin damage and malignancy...

Carbohydrates wound healing and immune function

Carbohydrates provide energy to wound cells, which helps in cell proliferation and phagocytic activity however, more recently, carbohydrates have also been shown to play a variety of non-energy-related roles via their functions as communication or recognition markers when they are formed into glycoproteins or glycolipids. These roles become extremely important after a trauma, when the body must mobilize an immune response. Recent work by Mori et al. showed that skin wound healing was impaired in mice that were P-1,4-galactosyltansferase deficient (28). Mice that were deficient in this key glycoprotein showed significantly delayed wound healing as well as reduced re-epithelialization, collagen synthesis, and angiogenesis. The authors speculate that the immune system is impacted, because both neutrophils and macrophages migrate into the wound site during wound healing, and this process is closely related to cell adhesion through interactions with selectins and their ligands. Chemokines...

Immune System

The immune system is made up of cells, tissues, organs, and processes that identify a substance as abnormal or foreign and prevent it from harming the body. Primary defenses include the white blood cells, but skin, mucosa, normal bacteria, enzymes, and proteins also provide protection. During times of stress and malnutrition, immune function may be decreased, meaning that susceptibility to illness is increased. Proper nutrition, including adequate protein, calories, and antioxidants (such as vitamin C, vitamin E, and beta-carotene, which are all found in fruits and vegetables) may help to improve immune response and reduce the risk of illness. SEE ALSO Infection.

Immune Functions

Reference has already been made to the role of NO in immunocompetence. Suchner et al. (2002) have reviewed the clinical evidence suggesting that NO may help in the regulation of inflammation and in enhancing the depressed immune response of patients suffering from injury, surgical trauma, malnutrition or sepsis. Exogenous source of arginine also imparts beneficial responses in terms of increased monocyte and lymphocyte proliferation and T-helper cell formation. Activation of macrophage cytotoxicity and increased cytokine production were also observed. However, the authors cautioned against the routine clinical use of exogenous arginine. The case for glutamine as an immune modulator (Tables 26.6 and 26.8) would appear to be particularly strong, when clinical evidence is considered (Andrews and Griffiths, 2002). All the diverse cells of the immune system appear to be dependent on glutamine for proper functioning. Glutamine not fully utilized for energy may become available for the...

Provision of Glutamine in Catabolicstress States in Humans

The provision of glutamine or glutamine 'precursors' (glutamine-containing dipeptides, N-acetylglutamine, 2-oxoglutarate, branched-chain amino acids), usually by the parenteral route, has been used in various catabolic situations in humans. In most cases, the intention was not to support the immune system but rather to maintain nitrogen balance, muscle mass and or gut integrity (for a review, see Furst et al., 1997). Nevertheless, the maintenance of plasma glutamine concentrations in such a group of patients very much at risk of immunosuppression might have the added benefit of maintaining immune function.

Overview and Conclusions

It is clear, from the foregoing discussions, that there is significant evidence, both experimental and clinical, to indicate that certain strains of probiotic organisms can modulate the immune system of the host. The two major impacts that have been demonstrated so far include immunostimulation and immunoregulation. Immunostimulation involves an elevation of immune function(s) to a heightened state of responsiveness, and may provide an important role in conditions where an elevation of immune function is not achievable by conventional means or in boosting responses among individuals with sub-optimal immunity. Experimentally, several strains of Lactobacillus and Bifidobacterium have been shown to boost humoral antibody responses to experimentally administered T-cell-dependent antigens (Portier et al., 1993 Perdigon et al., 1995 Gill et al., 2000). In human studies, Lactobacillus GG has been shown to enhance the humoral immune response to orally administered rotavirus and Salmonella...

Effects of other nutrients that might have an impact on glutathione status

Vitamin B6, although having no antioxidant properties, plays an important part in antioxidant defences, because of its action in the metabolic pathway for the formation of cysteine, which, as indicated earlier, is the rate-limiting precursor in glutathione synthesis. Vitamin B6 status has widespread effects upon immune function (Rall and Meydani, 1993). Vitamin B6 deficiency causes thymic atrophy and lymphocyte depletion in lymph nodes and spleen. Antigen processing is unaffected. However, the ability to make antibodies to sheep red blood cells is depressed. In human studies, the ability to make antibodies to tetanus and typhoid antigens is not seriously affected. Various aspects of cellmediated immunity are also influenced by vitamin B6 deficiency. Skin grafts in rats and mice survive longer during deficiency, and guinea pigs exhibit decreased delayed-hypersensitivity reactions to bacillus Calmette-Guerin (BCG) administration. Deficiency of vitamin B6 is rare in humans but can be...

Conclusions and Future Directions

Vitamin A has been used as both disease-targeted and prophylactic therapy to reduce morbidity and mortality from infectious diseases for hundreds of years. Vitamin A plays an important role in haematopoiesis, the maintenance of mucosal surfaces, the function of T and B lymphocytes, NK cells and neu-trophils, and the generation of antibody responses to T-cell-dependent and independent antigens. As an immune modulator, vitamin A reduces the severity but not the incidence of certain types of infections measles, diarrhoeal diseases, malaria and, possibly, infections related to pregnancy. Vitamin A does not appear to reduce the morbidity and mortality from ALRI. As a general rule, there appears to be little value in vitamin A supplementation in populations that are already relatively well-nourished and thus clinical investigation of immune modulation by vitamin A should be focused on populations at high risk of vitamin A deficiency. Despite the tremendous advances that have been made in...

Zinc and Infectious Diseases

Numerous animal studies indicate that Zn deficiency decreases resistance to a range of bacterial, viral, fungal and parasitic pathogens (for a review, see Shankar and Prasad, 1998), probably because of the immune impairments induced by the deficiency. Thus, the enhancing effect upon the immune response of providing Zn should translate into improved host defence and increased resistance to pathogens. However, most microorganisms require Zn for basic cellular processes (e.g. replication) and, during the acute-phase response, Zn is redistributed from the plasma to the liver and to lymphocytes (see Shankar and Prasad, 1998). It has been suggested that this is an adaptive response intended to deprive invading pathogens of Zn, facilitate immune function and prevent free-radical damage to cells. However, plasma Zn levels resulting from the acute-phase response remain generally well above the levels at which the growth of most pathogens is affected. The balance between Zn availability for...

The Future for Probiotics in Immune Health

For both immunostimulatory and immunoregulatory roles, contemporary research has already identified a few promising strains of immunoactive probi-otics (predominantly LAB) and these strains either are currently being commercialized or are near commercialization. An on-going need for research in this area is for continued safety monitoring, particularly among individuals with pre-existing health conditions. For example, among patients with active autoimmune conditions, probiotic strains that stimulate cellular immune function must receive particular and thorough attention to avoid the potential for disease exacerbation moreover, the safety of probiotics in subjects with deficient immune systems (e.g. acquired immune deficiency syndrome (AIDS) patients) should be considered. That aside, the essential requirement in all of these cases is not only that the probiotic under consideration is effective at influencing immunity but that it influences the immune system in the appropriate manner...

Alterations in membranemediated functions and signals

Changes in plasma membrane structural characteristics can change the activity of proteins that serve as ion channels, adhesion molecules, transporters, receptors, signal transducers or enzymes (Stubbs and Smith, 1984 Clandinin et al., 1991). Many membrane-associated proteins in immune cells have been shown to be modulated by membrane lipid changes. For example, feeding 5 w w long-chain n-3 PUFAs to rats resulted in a higher proportion of T- and B-cells and macrophages expressing the transferrin receptor (CD71) after stimulation with mitogen (Robinson and Field, 1998), although feeding a higher amount of fish oil did not induce this effect (Yaqoob et al., 1994b). The binding of cytokines to their receptor has been reported to be altered with changes in membrane composition (Grimble and Tappia, 1995). Additionally, the expression of several cell surface molecules was reported to be altered after fish oil feeding (Sanderson et al., 1995 Hughes et al., 1996 Robinson and Field, 1998...

Probiotics and infectious diseases

There is clear evidence that certain probiotic LAB strains are able to potentiate pathogen-specific antibody responses, both in animal models and in humans. Yasui et al. (1999b) have demonstrated that mice immunized with influenza vaccine and fed Bifidobacterium breve (strain YIT4064) as a probiotic developed enhanced virus-specific antibody responses and showed greater protection against respiratory challenge than non-probiotic-fed mice. In addition, some studies have confirmed an increase in innate and lymphoid cell-mediated events in pathogen-infected mice, which may contribute to enhanced disease resistance. Shu et al. (2000) have recently shown that the probiotic B. lactis HN019 could enhance pathogen-specific antibody responses in S. typhimurium-infected mice, as well as promoting increased peritoneal cell phagocytosis and splenic lympho-proliferative potential correlation analyses indicated that elevated immune function in probiotic-fed mice corresponded with reduced pathogen...

Sulphur amino acid metabolism

The sulphur amino acids are methionine and cysteine. Their metabolism is interlinked. As a result of this metabolism, the sulphur moiety is incorporated into a number of end-products, three of which, glutathione, taurine and proteins, have important roles in immune function. Methionine is a nutritionally essential amino acid, due to the inability of mammals to synthesize its carbon skeleton. Cysteine is considered to be semi-essential, in that it is synthesized from methionine provided that the dietary supply of the latter is sufficient. The methyl group of methionine can be removed from and reattached to the carbon skeleton of the amino acid by a cyclical process referred to as the transmethylation pathway (Fig. 7.1). The formation of homocysteine, part way along the transmethylation pathway, is an important branch point in the metabolism of methionine. Homocysteine can be remethylated to form methionine or can be metabolized by the transulphuration pathway to form cysteine (Fig....

Direct effects of glutathione

One of the first indications that glutathione influences aspects of immune function that are related to T lymphocytes came from a study in which the GSH content of lymphocytes was measured in a group of healthy volunteers (Kinscherf et al., 1994). The numbers of helper (CD4+) and cytotoxic (CD8+) T-cells increased in parallel with intracellular glutathione concentrations up to 30 nmol mg-1 protein. However, the relationship between cellular glutathione concentrations and cell numbers was complex, with numbers of both subsets declining at intracellular glutathione concentrations between 30 and 50 nmol mg-1 protein. The study also revealed that cell numbers were responsive to long-term changes in GSH content. When the subjects engaged in a programme of intensive physical exercise daily for 4 weeks, a fall in glutathione concentrations occurred. Individuals with glutathione concentrations in the optimal range before exercise who experi enced a fall in concentration after exercise showed...

Selection of methodology

The study of whole foods, fats and certain micronutrients and how these could influence immune function is currently under development. Fundamental observation of human PEM has shown that generalized malnutrition leads to impaired immune response and susceptibility to infection (see Chandra, Chapter 3, this volume). However, direct examination of how dietary intake of any particular nutrient affects the immune response is a complex undertaking. Table 2.1 includes four studies on dietary intake. Labeta et al. (2000) addressed the fundamental question of how human milk might activate the neonatal immune system by molecular mimicry through the isolation and sequencing of a relevant polypeptide. Fawzi et al. (2000) focused on how a whole food, specifically tomatoes, may protect against morbidity and mortality, an idea that has come from studies implicating antioxidants as improving immune function (see Hughes, Chapter 9, this volume). The relationship held true even with correction for...

Mechanism of Glutamine Action

There has been much speculation about the mechanism by which glutamine acts to preserve, or even improve, immune function. Similar metabolic characteristics apply to various cells of the immune system, despite the fact that their cell biology is different. Hence any hypothesis must explain high rates of gluta-mine utilization in cells with widely different cell-biological characteristics. As indicated earlier, glutamine makes a significant contribution to energy generation in cells of the immune system. However, oxidation of glutamine is only partial and immune cells can, and do, generate energy from other substrates (see Calder, 1995a). These observations suggest that the importance of gluta-mine to immune function is not simply through its action as an energy-yielding substrate. Another suggestion is that glutamine metabolism can generate intermediates for the synthesis of purines and pyrimidines and so provides the building blocks for mRNA and DNA. However, the rate of synthesis of...

Iron Status and Infection

The role of iron in cell division and cellular functions is well established. Almost all living cells, including bacteria, fungi, protozoa, mammalian cells from various tissues (including those of the immune system) require iron for DNA synthesis and many other cellular functions (Cazzalo et al., 1990). In addition to its role for ribonucleotide reductase activity, iron is also a cofactor of enzymes involved in cell respiration, antioxidant defence (catalase) and neutrophil bacterial killing (myeloperoxidase). Microorganisms need iron in the concentration range of 22-220 g l-1 (Payne and Finkelstein, 1978). Although an insufficient supply of iron will diminish the growth of microorganisms (Patruta and Horl, 1999), the iron in human body fluids and tissues is potentially more than sufficient to sustain optimal growth of microorganisms (Fairbank, 1988 Cook and Skikne, 1989 Cazzalo et al., 1990). However, this iron is tightly bound to various proteins (haemoglobin, myoglobin, ferritin,...

Health Benefits of Probioticmediated Immunomodulation

As described previously, probiotics are capable of modulating the immune system via both immunostimulation and immunoregulation, and thus have the potential to have an impact on health status and disease conditions that have an inherent immune component. In the case of immunostimulation, probiotics may provide a boosting of the immune system in key aspects of effector mechanisms that are tailored towards combating infectious diseases or intrinsic pathologies, such as neoplasm development. In addition, the ability of probi-

Probiotic Supplementation of the Intestinal Microflora

Among the many purported physiological influences of probiotic microorganisms, a large proportion of research attention over the last decade has focused on the interaction of probiotics with the immune system (Salminen et al., 1998). It is evident that several probiotic strains of lactic acid bacteria (LAB) are able to influence the immune system and, in many cases, this effect has been linked to a measurable improvement in health. The immune system comprises innate and adaptive components, and these play vital interacting roles in health maintenance, in both regulating and stimulating the body's responses.

Protein Energy Malnutrition

From a historical perspective, it is useful to cite the clinical stimulus that led to the first comprehensive examination of the immune system in PEM (Chandra, 1972). Interest in nutrition-immune interactions was kindled by the story, with an unhappy ending, of a child. Eighteen-month-old Kamala was thin, her skin pale as wax and her lungs screaming for air. She wore a spectral CAB International 2002. Nutrition and Immune Function (eds P.C. Calder, C.J. Field and H.S. Gill) white death-mask in a frame of black hair. Her shrivelled body and swollen legs were typical of marasmic kwashiorkor, and she had an obvious fulminant infection. Lung aspirate revealed the opportunistic organism Pneumocystis carinii. Despite our best efforts, we lost the child. We speculated that malnutrition had robbed Kamala of her defences against infection and led to her premature demise. Against this background in 1969, I applied the available techniques to study the immunocompetence of undernourished...

Nitric oxide pathway of arginine metabolism

No one molecule has attracted more attention in the last decade than nitric oxide (NO). This small molecule plays a pivotal role in a diverse range of functions, including vasodilatation, memory, peristalsis, penile erection, cytotoxicity and the control of various endocrine and exocrine secretions in the cardiovascular, reproductive, central nervous and immune systems (Nathan and Xie, 1994 MacMicking et al., 1997). NO is synthesized from arginine by nitric oxide synthase (NOS), with the formation of citrulline. There are three known forms of this enzyme neuronal (nNOS) and endothelial cell (ecNOS) NO synthases, which are both constitutively expressed and calcium-activated, and an inducible form (iNOS), which is controlled at the transcriptional level and is of most interest in the setting of the immune system. inducing cell injury and death (Samar et al., 1997). Apart from its cytotoxic effects, NO is involved in regulating the expression of major histocompatibility complex (MHC) II...

Glutamine feeding studies in healthy animals

Fed the glutamine-enriched diet (Kew et al., 1999), while the production of all three cytokines investigated (TNF-a, IL-1p and IL-6) was greater for LPS-stim-ulated macrophages from mice fed the glutamine-enriched diet (Wells et al., 1999). These observations suggest that increasing the amount of glutamine in the murine diet enhances the ability of both macrophages and T lymphocytes to respond to stimulation, at least in terms of cytokine production. Feeding rats a glutamine-free diet for 7 days resulted in decreased mucosal wet weight and a decreased number of intraepithelial lymphocytes (Horvath et al., 1996). This study suggests that glutamine is required for maintenance of the gut-associated immune system.

Immune cells and macrophages

A variety of leucocytes occur in colostrum ( 4 x 106 ml-1) and later in milk ( 105 ml-1). Macrophages (55-60 ) and polymorphonuclear granulocytes (30-40 ) dominate over lymphocytes (5-10 ), the latter being mainly (75-80 ) T lymphocytes (Goldman, 1993 Wold and Hanson, 1994). Oral administration of macrophages in newborn mice showed survival of these cells for several hours in the gut and even some mucosal uptake (Hughes et al., 1988). Experiments with milk leucocytes in newborn rats, calves and lambs likewise demonstrated transepithelial migration, lymphocytes apparently being the predominant cell type (Slade and Schwartz, 1987). Also, the distribution of labelled human colostral leucocytes after enteral administration in premature baboons suggested epithelial adherence in the gut, as well as mucosal uptake and persistence for more than 60 h, along with some peripheral migration (Jain et al., 1989). The contribution of milk lymphocytes to the infant's developing intestinal immune...

Secretory antibodies and free SC

Because the lactating mammary glands are part of the integrated mucosal immune system (Fig.14.4), milk antibodies will reflect antigenic stimulation of MALT in the gut as well as in the airways, as mentioned earlier. The secretory antibodies are thus highly targetted against infectious agents in the mother's environment, which are those likely to be encountered by the baby during its first weeks of life. As mentioned previously, antibodies against various dietary antigens, such as gluten and cow's milk proteins, as well as against other potential allergens (Casas et al., 2000), are also often present in breast milk. The possible role of these IgA antibodies for the clinical presentation of immune-mediated adverse reactions to food in the infant will be discussed below.

Effector functions of immunoglobulins

The humoral arm of the adaptive immune responses is particularly effective against extracellular microorganisms and their toxins. Antibodies bind to functionally critical antigenic sites on soluble toxins and to the surface antigens of extracellular microorganisms. Such binding effectively neutralizes toxins and microorganisms by preventing binding to host-cell surface molecules. Antibodies bound to bacteria are also able to activate a series of plasma proteins, known as complement, to produce molecules that are chemotactic for phagocytes, promote phagocytosis and can also directly destroy bacteria (Lambris et al., 1999). Antibodies bind to bacteria by the amino-terminal antigen-binding sites, leaving the Fc component of the antibody exposed. Engagement of these exposed Fc fragments by surface Fc receptors on phagocytic cells induces phagocytosis and destruction of the coated bacterium this process is known as opsonization. Macrophages and neutrophils possess IgM- and IgG-specific Fc...

Effect on productive mucosal immunity development

Numerous studies of the effect of breast-feeding on secretory immunity have been performed with salivary IgA measurements as a read-out system. Discrepant observations have been made, probably to some extent reflecting different cytokine levels in the milk as discussed above. The influence of contaminating the saliva sample with milk SIgA, shielding of the suckling's mucosal immune system by maternal SIgA antibodies, and altered growth and composition of the infant's gut flora have been discussed as additional uncontrollable variables (Brandtzaeg et al., 1991). However, the balance of accumulated data suggests that breast-feeding promotes the post-natal development of secretory immunity (Wold and Hanson, 1994 Brandtzaeg, 1998), apparently even in the urinary tract (Newman, 1995) and there are reports of enhanced secretory, as well as systemic, immune responses to oral and parenteral vaccines in breastfed babies (Hahn-Zoric et al., 1990 Pabst and Spady, 1990). Nevertheless, several...

Probiotic effects on antibody responses

Several studies have investigated the ability of probiotics to regulate antibody production. Initial animal studies showed that probiotics were able to potentiate systemic antibody responses to parenterally delivered foreign antigens in mice (Portier et al., 1993) and that serum levels of IgG and IgM isotypes were elevated (Perdigon et al., 1991, 1999). Subsequent studies have indicated that probiotic strains such as L. rhamnosus HN001 or B. lactis HN019 can potentiate antibody responses to both systemically and orally administered T-dependent antigens in mice and that increases in specific antibody titre can be measured in both the serum and intestinal-tract secretions, the latter involving a rise in IgA levels (Yasui et al., 1989 Yasui and Ohwaki, 1991 Herias et al., 1999 Tejada-Simon et al., 1999a Gill et al., 2000). Since the major GI antibody secretion is derived from plasma cells of the lamina propria, these results suggest that probiotics are able to stimulate the mucosal...

Probiotic effects on innate cell defences

A large body of work concerned with definition of probiotic effects on the immune system has focused on innate cell responses. Early studies had shown that oral delivery of L. casei probiotic strains to mice could activate mononuclear phagocytes for increased phagocytic activity and lysosomal enzyme production and that this enhancement could be detected in cells derived from peritoneal exudates (Perdigon et al., 1986, 1988). Subsequent studies have confirmed that certain strains of probiotic LAB can prime peritoneal macrophage populations for enhanced phagocytosis, lysosomal enzyme production and free radical oxidant production (Perdigon et al., 1988 Gill, 1998 Matsuzaki and Chin, 2000). Further studies in murine models have reported that probiotic feeding can also enhance the activity of blood-derived phagocytes and that both mononuclear (monocyte) and polymorphonuclear (neutrophil) populations are stimulated by probiotics (Gill et al., 2000). Human studies have confirmed this effect...

Bcell homing to mammary glands

Lactating mammary glands are part of the integrated mucosal immune system, and milk antibodies reflect antigenic stimulation of MALT in the gut as well as in the airways. This fact has been documented by showing that SIgA from breast milk exhibits antibody specificities for an array of common intestinal and respiratory pathogens (Goldman, 1993). The secretory antibodies are thus highly targeted against infectious agents in the mother's environment, which are those likely to be encountered by the infant during its first weeks of life. Therefore, breast-feeding represents an ingenious immunological integration of mother and child (Fig. 14.4). Although the protection provided by this humoral defence mechanism is most readily demonstrable in populations living in poor sanitary conditions (Hanson et al., 1993 Anon., 1994), a beneficial clinical effect is also apparent in the industrialized world (Wold and Hanson, 1994),

Effects of antigen exposure and nutrition on secretory immunity

The degree of antigenic and mitogenic exposure is decisive not only for the post-natal development of IELs, but also for the secretory immune system. Antigenic constituents of food clearly exert a stimulatory effect on the intestinal B-cell system, as suggested by the occurrence of fewer lamina propria IgA immunocytes both in mice fed on hydrolysed milk proteins (Sagie et al., 1974) and in parenterally fed babies (Knox, 1986). Likewise, mice given total parenteral (intravenous) nutrition have reduced numbers of B- and T-cells in the gut, as well as decreased SIgA levels (Li et al., 1995a, b Janu et al., 1997), and they show impaired SIgA-dependent influenza-specific immunity (Renegar et al., 2001). The effect of food in the gut lumen could be direct immune stimulation or mediated via release of gastrointestinal neuropeptides. The indigenous microbial flora is also extremely important for secretory immunity, as shown by

Plasma and Muscle Glutamine Levels in Catabolic Stress

Animal studies indicate that intramuscular and plasma glutamine concentrations are decreased in catabolic-stress situations, such as in sepsis and cancer cachexia and following burn injury and surgery (Table 6.3). In humans, plasma glutamine levels are lowered (by up to 50 ) by sepsis, major injury and burns and following surgery (see Table 6.4). A recent study reported that low plasma glutamine concentration (< 0.42 mM) at admission to intensive care was associated with higher severity of illness and higher mortality (Oudemans-van Straaten et al., 2001). In humans, the skeletal-muscle glutamine concentration is lowered by more than 50 in catabolic stress (see Table 6.4). These observations indicate that a significant depletion of the skeletal-muscle glutamine pool is characteristic of catabolic stress. The lowered plasma glutamine concentrations that occur are most probably the result of demand for glutamine (by the liver, kidney, gut and immune system) exceeding the supply, and it...

Alterations in membrane structure and composition

The fluidity of the plasma membrane or of regions of the plasma membrane is important in the functioning of cells (see Stubbs and Smith, 1984). The fluidity of a membrane is determined by its lipid components and their fatty-acid composition (Stubbs and Smith, 1984). Membrane fluidity is an important regulator of phagocytosis (Calder et al., 1990). The function of the immune system depends on interactions between different cell types and, through effects on membrane composition, dietary fatty acids have the potential to influence these interactions. For example, the interaction of cytotoxic T-cells with target cell membranes, a necessary interaction to induce effector function, is affected by the fluidity of the plasma membrane of the T-cells (Bialick et al., 1984). Cell culture experiments have demonstrated that changes in fatty-acid composition of immune cells alter membrane fluidity (e.g. Calder et al., 1994), but this has been less easy to demonstrate after dietary manipulations...

Clinical Application and Intervention Strategies

The interactions between nutrition, the immune system and infection have much clinical and public health significance (Chandra, 1992). The fact that changes in immune responses occur early in the course of nutritional deficiency has led to the suggestion that immunocompetence can be used as a sensitive functional indicator of nutritional status. In patients with obvious primary or secondary malnutrition, the number of T lymphocytes is a useful measure of response to supplementation therapy. Anergy and other immunological changes correlate with poor outcome, in both medical and surgical patients, if impaired immunity is considered in association with hypoalbuminaemia (Chandra, 1983a,b,c). Opportunist infections occur more frequently among those patients with cancer who are also malnourished. The incidence of complicating infections can be reduced if appropriate preventive and therapeutic nutritional management is carried out in patients with leukaemia. It has been postulated that...

Handling of absorbed food antigens

Several routes may be visualized for the penetration of intact soluble antigens through the normal intestinal epithelium paracellular diffusion bypassing the tight junctions via epithelial discontinuities, such as the cell extrusion zones of the villus tips translocation through enterocytes by endocytosis and subsequent exocytosis or transport by M cells in GALT. As discussed elsewhere (Brandtzaeg et al., 1987 Brandtzaeg, 1996a), the relative importance of these mechanisms remains unknown, and the consequences in terms of sensitization or induction of oral tolerance probably depend on the route of uptake, as well as on the nature of the antigen - that is, soluble, lectin-like or particulate (Fig. 14.8). There is likewise no definite knowledge about the effects transmission of food antigens to breast milk might have on the suckling's immune system (Zeiger, 2000 Hoppu et al., 2001), although animal experiments have suggested the possibility of tolerance induction (Johansen et al., 2001).

Immunoglobulin isotypes

IgM dominates the initial humoral immune response however, IgG and IgA predominate later, although IgE is prominent during an allergic response. This process is known as isotype switching and is the consequence of DNA rearrangements in the genes encoding for the C (but not the V) regions of the heavy chains (Stavnezer, 1996). Isotype switching results in differing classes of antibodies with differing functional properties, although antigen specificity remains constant. Isotype switching is dependent on T-cells and their secretion of cytokines, with interleukin-4 (IL-4) inducing B-cell switching to IgE this is antagonized by interferon-7 (IFN-7) (Pene et al., 1988). Switching to IgA is promoted by transforming growth factor-p (TGF-p), in combination with IL-10 (Defrance et al., 1992). In addition to isotype switching, as the humoral immune response matures, point mutations in the immunoglobulin V-region genes occur. A T-cell-dependent process, known as affinity maturation, selects...

The generation of effector Tcells Janeway and Bottomly

Activation of a T-cell is a complex, tightly regulated process. This is necessary in order to ensure that T-cell activation is directed only against pathogens and not against body tissues. Furthermore, increased complexity decreases the likelihood that a microorganism can evolve mechanisms to subvert T-cell activation. T-cell activation takes place in the peripheral lymphoid organs. However, before this can occur, antigen is processed and presented in association with MHC molecules, and the antigen is then transported from the site of infection to the peripheral lymphoid organs and presented to T-cells. The processing, transportation and presentation of antigen are performed by antigen-presenting cells, the most important and efficient of which are dendritic cells. Dendritic cells are mandatory for the initiation of a primary immune response against a new pathogen, although both dendritic cells and non-professional antigen-presenting cells, such as macrophages and B-cells, are able to...

Dendritic Tcell interactions

Effector CD8 T-cells (also known as cytotoxic T-cells) play a vital role in counteracting viral infections (Fig. 1.5), which are intracellular and almost completely hidden from the humoral immune response. Effector CD8 T-cells are Although CD8 effector T-cells are of major importance in the defence against viruses, they are ineffective in eliminating certain intracellular bacteria, fungi and parasites that are not neutralized by destruction of their host cell. These microorganisms are also resistant to the humoral immune response. These particularly resistant organisms are neutralized by effector CD4 T-cells, which are generated by MHC class II-restricted presentation of peptide by antigen-presenting cells. Effector CD4 T-cells are more commonly known as T-helper (Th) cells.

Control of sulphur amino acid metabolism

From the kinetics of the key enzymes in sulphur amino acid metabolism reported above, it can be seen that, when the diet is low in sulphur amino acids, cellular methionine is highly conserved. Flux down the transulphuration pathway, which ultimately leads to methionine catabolism, increases only as dietary methionine intake increases. It can also be seen that, at low flux rates of substrate down the transulphuration pathway, conversion of cysteine into its main metabolites will be affected, so that protein synthesis will be relatively maintained while sulphate and GSH synthesis rates will fall. Synthesis of GSH and sulphate will increase in concert as increasing levels of substrate flow through the pathway. In a study in rats, seven molecules of cysteine were incorporated into GSH for every ten incorporated into protein in liver at adequate sulphur amino acid intake (Grimble and Grimble, 1998). At inadequate sulphur amino acid intake, the ratio fell to < 3 10. This response to a low...

Putative involvement of lymphoepithelial interactions

Jected to active tolerance induction (Nagler-Anderson, 2000) or anergy, with no capacity for production of their own growth-factor IL-2 upon restimulation (Janeway and Bottomly, 1994). The required co-stimulation for productive immunity is provided by soluble mediators, such as IL-1, and through cellular interactions, especially ligation of B7 (CD80 CD86) on professional APCs with CD28 on the T-cells (Robey and Allison, 1995). There is particularly great interest in the role of DCs in shaping the phenotypes of naive T-cells during such initial priming. Also, because DCs have migratory properties, they largely determine the tissue site in which primary immune responses will take place (Holt and Stumbles, 2000 Lanzavecchia and Sallusto, 2001). Fig. 14.6. Schematic representation of polarized patterns of cytokines produced by activated T-helper (Th) cells. When naive CD4+ Th cells are primed by a professional antigen-presenting cell (APC) providing adequate co-stimulatory signals, they...

Effects of selenium on viral infections

The long terminal repeat of HIV controls replication and is activated by binding of NFkB, which is regulated by the cell redox state and oxidative stress. TNF-a stimulates NFkB activation in T-cells. As we have described, Se compounds can inhibit TNF-a release. An inverse correlation between plasma Se concentration, red-cell GPX activity and the progression of acquired immune deficiency syndrome (AIDS) has been shown (reviewed in Chen et al., 1997 McKenzie et al., 2002). In culture, Se supplementation of HIV-infected monocytes and CD4+ T-cells inhibits TNF-a-induced viral replication (Hori et al., 1997). Thus, it seems that Se may be useful in the treatment of AIDS (Chen et al., 1997). Dietary Se supplements have been used for the treatment of hepati-tis-B-induced liver cancer in China. The incidence of hepatitis-B-virus-induced liver cancer in humans decreased in a previously Se-deficient, hepatitis-B+ population given Se supplements of 200 g day-1.

The secretory antibody system and its function

Diagram Gut Lumen Lamina Propria

Interestingly, free SC released to the lumen (Fig. 14.2) may on its own be able to block epithelial adhesion of E. coli (Giugliano et al., 1995) and can bind the potent toxin of Clostridium difficile (Dallas and Rolfe, 1998). Also, a pneumococcal surface protein (SpsA) has been shown to interact with both free and bound SC (Hammerschmidt et al., 1997). Such observations suggest that SC has phylogenetically originated from the innate defence system before being exploited by the adaptive secretory immune system to function as pIgR.

Integration and regionalization

Balt Immune Function

Lymphoid cells are located in three distinct compartments in the gut organized gut-associated lymphoid tissue (GALT), the lamina propria and the surface epithelium. GALT comprises the Peyer's patches, the appendix and numerous solitary lymphoid follicles, especially in the large bowel (O'Leary and Sweeney, 1986). All these lymphoid structures are believed to represent inductive sites for intestinal immune responses (Brandtzaeg et al., 1999a). The lamina propria and epithelial compartment constitute effector sites but are nevertheless important in terms of cellular expansion and differentiation within the mucosal immune system. GALT and other MALT structures (see below) are covered by a characteristic follicle-associated epithelium (FAE), which contains membrane (M) cells (Figs 14.1 and 14.3). These specialized thin epithelial cells are particularly effective in the uptake of live and dead antigens from the gut lumen, especially when they are of a particulate nature (Hathaway and...

Endocrine effects of arginine

Elevated plasma levels of arginine have been found to correlate with increased secretion of various hormones, including prolactin and growth hormone from the pituitary, insulin, glucagon, insulin-like growth factor 1 (IGF-1) and adrenal catecholamines (see Barbul, 1996). These hormones, in turn, can affect the functioning of the immune system. While the powerful secretagogue action of arginine is largely unexplained, a direct cholinergic effect, membrane depolarization by this highly cationic molecule and subsequent calcium influx, and the use of NO as an intermediary in cell signalling have all been demonstrated.

Importance of homoeostatic immune regulation

Similarly, there is some hope that immunization with mycobacterial antigens might skew the cytokine profile towards Th1 and thereby, through cross-regulation, dampen Th2-dependent allergic (atopic) symptoms (von Reyn et al., 1997 Hopkin et al., 1998). Newborns are in fact able to mount a Th1-type immune response when appropriately stimulated (Marchant et al., 1999). Also notably, the bacterial endotoxin or LPS receptor CD14, together with the Tolllike receptor (TLR) 4 on APCs, as well as other TLRs that recognize microbial products (e.g. lipoproteins and peptidoglycans) as danger signals or pathogen-associated molecular patterns (PAMPs), are in this respect an important link between innate and specific immunity (Fig. 14.6). This link operates via the nuclear factor kappa B (NFkB) activation pathway to release pro-inflammatory cytokines (Modlin, 2000 Kaisho and Akira, 2001), including the Th1-inducing IL-12 and IL-18 (McInnes et al., 2000 Manigold et al., 2000). Even certain CpG...

Changes in eicosanoid synthesis

Anti Tumour Neutrophil

A key link between fatty acids, inflammation and immune function is a group of bioactive mediators termed eicosanoids (prostaglandins, leucotrienes, thromboxanes), which are synthesized from 20-carbon PUFAs (Fig. 4.4). The two Eicosanoids (particularly PGE2 and 4-series LT) are involved in modulating the intensity and duration of inflammatory and immune responses (for reviews, see Kinsella et al., 1990 Lewis et al., 1990 Tilley et al., 2001). The pro-inflammatory effects of PGE2 include inducing fever, increasing vascular permeability result in less inflammation, enhanced cytokine production by monocytes macrophages and Th1 lymphocytes and enhanced lymphocyte proliferation (Fig. 4.9). The reduction in the generation of arachidonic acid-derived mediators that accompanies fish oil consumption has led to the idea that fish oil is anti-inflammatory and might enhance immune function (Fig. 4.9). However, the in vivo situation is likely to be more complex than this, because PGE2 is not the...

Immunoregulation and Stimulation by Probiotics Laboratory and Clinical Studies

Although the primary site of immunological signalling is at the gut mucosal interface, there is evidence that the immunomodulatory effects of probiotics can be expressed systemically. Typically, this is manifested by changes in leucocyte or humoral function, which can be assessed by ex vivo assays. To date, several compartments of the immune system have been identified as affected by probiotic delivery, including lymphocyte function (proliferation, cytokine secretion and cellular cytotoxicity) innate cell defences (e.g. phagocytosis, oxidative radical production, lysosomal enzyme secretion) natural cytocidal function of macrophages and natural killer (NK) cells, and antibody responses (both in terms of total immunoglobulin (Ig) levels and antigen-specific responses) (Table 13.1). In addition, there is evidence that oral delivery of probiotics can influence cellular phenotype expression, both at the mucosal interface and systemically, to reflect a state of activation.

Introduction and Overview

Nutrients are primary factors in the regulation of the human immune response. Both macronutrients and micronutrients derived from the diet affect immune-system function through actions at several levels in the gastrointestinal tract, thymus, spleen, regional lymph nodes and immune cells of the circulating blood (Chandra, 1997 Cunningham-Rundles and Lin, 1998 Wallace et al., 2000 Cunningham-Rundles, 2001). Effects at one level may be opposed or modified at another level. Thus, the development of an experimental approach capable of revealing critical interactions requires study of more than one aspect of immune function (Cunningham-Rundles, 1993 Muga and Grider, 1999 Beisel, 2000). The effect of any single nutrient is dependent upon concentration, interactions with other key nutrients, host genetic expression and internal environmental conditions. In situations of nutrient imbalance, duration of the altered condition and age of the host are also often critical factors...

Effects of Iron Deficiency on Immunity

There are many cell-mediated immune responses that have been investigated in iron-deficient subjects and laboratory animals (Table 11.1). In children and adults, iron deficiency resulting from dietary restriction reduces the proportion of T lymphocytes in blood, although the absolute number of T-cells can be either reduced or unchanged (Chandra and Saraya, 1975 Srikantia et al., 1976 Bagchi et al., 1980 Prema et al., 1982 Swarup-Mitra and Sinha, 1984 Kemahli et al., 1988 Vydyborets, 2000). However, based on the report of Santos and Falcao (1990), it appears that iron deficiency resulting from blood loss does not reduce the proportion of T-cells in blood, but it does decrease total T-cell numbers. The discrepancy between these types of iron deficiency is probably related to the long period of time required for the development of iron deficiency by dietary restriction as compared with blood loss. The absolute numbers and proportions of CD4+ and CD8+ T-cells are either decreased or...

Historical overview

Deficiency of vitamin A (Bloch, 1924). Milk, cream and butter were advocated to reduce infections in children (Bloch, 1924). Subsequently, vitamin A was evaluated in at least 30 therapeutic trials in various infections (e.g. Green and Mellanby, 1928 Ellison, 1932). It is now recognized that vitamin A modulates many different aspects of immune function, including components of both nonspecific immunity (e.g. phagocytosis, maintenance of mucosal surfaces) and specific immunity (e.g. generation of antibody responses). Much of our knowledge of vitamin A and immune function is derived from experimental animal studies involving mice, rats and chickens. The effects of vitamin A deficiency on aspects of immune function are summarized in Table 8.1.

Conclusion

Zn has a number of key roles relating to cell signalling, cell activation, gene expression, protein synthesis and apoptosis. Zn is crucial for the normal development of immune cells. Zn plays an important role in maintaining the activity of a range of immune cells, including neutrophils, monocytes, NK cells, B-cells and T-cells, and Zn-deficient individuals have increased susceptibility to a variety of pathogens. Providing Zn for deficient individuals improves immune function and host defence. Studies in at-risk groups indicate significant decreases in the incidence and severity of infectious disease when Zn is provided.

Per Brandtzaeg

In the process of evolution, the mucosal immune system has generated two arms of adaptive defence (i) antigen exclusion, performed by secretory antibodies of the immunoglobulin (Ig)A and IgM classes, to modulate or inhibit surface colonization of microorganisms and dampen penetration of potentially dangerous soluble agents and (ii) suppressive mechanisms to avoid local and peripheral overreaction (hypersensitivity) against innocuous substances bombarding the mucosal surfaces (Fig. 14.1). The latter arm is referred to as 'oral tolerance' when induced via the gut against dietary antigens (Brandtzaeg, 1996a) it probably explains why overt and persistent hypersensitivity to food proteins is relatively rare (Bischoff et al., 2000). Similar down-regulatory mechanisms apparently operate against antigens from the commensal microbial flora (Duchmann et al., 1997 Karlsson et al., 1999 Helgeland and Brandtzaeg, Oral tolerance generally seems to be a rather robust adaptive immune function, in...

Immune assessment

New assay methods have enabled the design of experiments addressing different stages involved in immune-cell activation and the study of effects on signalling pathways, which may then lead to the characterization of causal relationships. Table 2.2 outlines some of the types of methods currently in use. Most investigations begin with a general assessment of how a nutrient or altered nutritional state affects the general parameters of the immune system, immune-cell subsets and function. Measurement of changes in frequency and number of circulating lymphocyte subpopulations in the course of observation or dietary intervention is now accepted as a useful and widely comparable procedure, but attention must be given to the issue of controls This analysis should include standardized performance of immunophenotyping, using correction for purity of the gating region, quantitative recovery of the cell type and positive identification of cellular subsets. For human studies, a complete blood...

Summary

The immune system has evolved to combat the constant threat of tissue invasion by microorganisms. If, however, the immune system is directed against innocuous antigens or tissue antigens, the same immune responses that are vital for defence against microorganisms can result in autoimmune disease and allergy. The adaptive immune response is reliant on the properties of B- and T-cells that enable the response to be powerful, flexible and antigen-specific and exhibit immunological memory. B-cells secrete antibodies that are effective against extracellular bacteria and their toxins, whereas CD8 T-cells are adept at neutralizing virally infected cells. CD4 T-cells, also known as Th-cells, do not directly neutralize invading pathogens instead, they interact with other cells (e.g. macrophages and B-cells) to direct a coordinated, antigen-specific immune response against microorganisms. CD4 Th-cell differentiation can be usefully considered to be either Th1- or Th2-biased. Th1-biased immune...

Conclusions

Because the immune system is critically dependent on accurate cell-cell communication in order to mount a response, immune cell integrity is essential. Antioxidant nutrients help to maintain this integrity, reducing the damage caused by reactive oxygen species to cell membranes and their associated receptors, as well as modulating immune cell function by influencing the activity of redox-sensitive transcription factors and the production of cytokines and PGs. The effects of antioxidants appear to be particularly beneficial during periods of oxidative stress, whether the periods are acute, such as during infections, or chronic, such as in the elderly. However, the results of the prospective studies with p-carotene in smokers show that caution must still be taken in making recommendations regarding the taking of supplements that provide a greater intake than can be achieved by eating a diet rich in fruits and vegetables. In this regard, it is important to remember that the strongest...

Immune activators

Relatively non-pathogenic viruses, such as measles, are often fatal in children with PEM, because measles-virus infection causes a serious but usually transient suppression of the cellular immune response (Schlender et al., 1996 Ito et al., 1997), which, in the malnourished host, may continue to prevent immune clearance. Longitudinal studies are often essential to demonstrate long-term effects, such as the lingering effect of vitamin A deficiency, which increases mortality from infections (West et al., 1999). Current studies suggest that the specificity of the response, defined as a Th1 or Th2 cytokine-pattern, to a specific microbe is critically associated with host defence. Study designs that incorporate antigens that are actually being encountered at the time of study or that focus on the type of cytokine production may therefore provide important and unique information.

Thcells and Bcells

In general, B-cell activation requires signals from two sources the first arises from the binding of B-cell surface-bound IgM D to the complementary microorganism surface epitope and the second is Th-cell-derived (Fig. 1.7). This Th-cell facilitation of B-cell activation is essential for full expression of the humoral immune response, particularly isotype switching, affinity maturation and the efficient development of memory B-cells. To enable Th-cell facilitation of B-cell activation, B-cells are able to internalize antigen-immunoglobulin complexes and then express the resulting pathogen peptide sequences in an MHC class II-restricted fashion on the B-cell surface. It is these peptide-MHC class II complexes that are recognized by the Th-cell. It is essential that the pep-tide sequences recognized by the Th-cell originate from the antigen recognized by the B-cell. This process of linked recognition means that the B-cell and the Th-cell respond to different epitopes however, the...

Overview

Daily Se intakes of humans can vary across the globe from less than 5 g day-1 up to 3000 g day-1. However, these intakes represent extremes and, in most cases, Se intakes are between 30 and 200 g day-1. With regard to human health issues, most debate revolves around whether intakes of 30-75 g day-1 are associated with an increased incidence of a range of diseases, including cardiovascular disease and cancers. Low dietary Se intake has been implicated in the development of numerous health disorders in humans. These include Kashin-Beck disease, cancer, cardiovascular disease (including Keshan disease), muscular dystrophy, malaria, alopecia areata, pregnancy hypertension syndrome, altered immune function, male infertility and even AIDS (reviewed in Rayman, 2000). Patients on long-term parenteral nutrition without Se supplementation in their formulation run the risk of Se deficiency, which is manifested in myopathy and cardiomyopathy. Low Se status (low Se and erythrocyte GPX activity) in...

Effects on Health and Performance

Female athletes who experience menstrual dysfunction, particularly amenor-rhea, often show little concern for the disruption in their cycles some even express relief at the ''break.'' Similarly, some coaches simply dismiss menstrual dysfunction, believing it is a natural result of hard training 18 . Nonetheless, despite these attitudes, it should be emphasized that menstrual dysfunction is not a normal response to training rather, it is a clear indication that health is being compromised. The health consequences of menstrual dysfunction are well documented and include infertility and other reproductive problems, decreased immune function, an increase in cardiovascular risk factors, and, perhaps most importantly, decreased BMD and increased risk for premature osteoporosis 2,52 .

Other roles of vitamin E

Vitamin E is the most effective chain-breaking lipid-soluble antioxidant in biological membranes, where it contributes to membrane stability and protects critical cellular structures against damage from free radicals and reactive products of lipid oxidation (Burton and Ingold, 1981). There are suggestions however that it has a variety of other effects, for example on immune function, platelet and vascular functions, prevention of oxidative damage to DNA and DNA repair and modulation of signal transduction pathways (Morrissey and Sheehy, 1999). Immune function in the elderly is often the focus of vitamin-supplementation studies but, while some workers, e.g. Meydani et al (1997), were able to demon strate improvements in both cellular and humoral responses from vitamin E supplements, others who used less vitamin E (67 mg aTE d) were unable to do so (de Waart et al, 1997). Meydani and colleagues suggested that a consumption of at least 147mg a-TE d (ie 5-10 times a normal dietary intake)...

Antioxidant Vitamins A Closer Look

Just what are antioxidants They're a handful of vitamins, minerals, carotenoids, and polyphenols present in a variety of foods that significantly slow or prevent the oxidative (damage from oxygen) process and so prevent or repair damage to your body cells. They may also improve immune function and perhaps lower risk for infection and cancer. What makes them unique What foods supply them naturally How

Micronutrient status and pregnancy outcomes in hivinfected women

(MTCT) of HIV by impairing systemic immune function and by affecting the epithelial integrity of the maternal lower genital tract 27, 28 . Deficiencies of various micro-nutrients may amplify the risk of postpartum HIV transmission by increasing the risk of clinical or subclinical mastitis and subsequent viral shedding, and by impairing the epithelial integrity of the infant gastrointestinal tract 27, 29 . Micronutrient deficiencies may also accelerate clinical, immunologic, and virologic HIV disease progression, and consequently increase maternal morbidity and risk of HIV transmission 3, 27 . Further, HIV infection itself may affect nutrient absorption and contribute to the development of micronutrient deficiencies and wasting, thus perpetuating a vicious cycle 30 .

Nutrition and Immunity

Immune suppression can occur even with single nutrient deficiencies for example, you can have excellent general nutrition, but an isolated deficiency in say, pyridoxine, will trigger immune suppression. The same is true for most of the B vitamins, vitamins C, E, and D, and magnesium, zinc, boron, iron, and selenium. Supplying these people with a balance of high-quality protein and adequate calories can quickly restore immune function to normal.

Ergogenic effects Endurance Activities

The speculation that glutamine supplementation can enhance performance during endurance activities is largely based on the acute immune system suppression observed during strenuous exercise. Since glutamine is utilized as a fuel source for immune system cells, the assumption is that supplementary glutamine will attenuate the mobilization of glutamine from the skeletal muscle. Prolonged endurance exercise, such as marathon running, may reduce plasma glutamine concentration. Plasma glutamine concentrations seem to significantly decrease in overtrained athletes compared to control, nonovertrained athletes.36 Physical stress such as illness or increased physical activity can induce hypercatabolic states, thereby decreasing the body's endogenous rate of glutamine synthesis, making it a conditionally essential amino acid. Early studies suggested that glutamine may be beneficial to endurance athletes because of its impact on muscle glycogen synthesis, by serving as a substrate for...

Dr Christopher Calpai

Mercury is released during the placement and removal of amalgams. Areas of concern with regards to mercury exposure include kidney dysfunction, neurotoxicity, reduced immune function, hypersensitivity reactions, birth defects and overall changes in general health. The latest and best treatment is a combination of oral vitamins and minerals to maximize immune function, exercise, and intravenous EDTA chelation therapy to remove the metals. Vitamin C is also beneficial. Some people use intravenous vitamin C and alternate that with chelation.

The nutritional role of copper

Copper was identified as an essential trace element, first for animals1 and subsequently for humans2 when anaemia was successfully treated by supplementing the diet with a source of copper. Since then the full significance of its role in biological systems has continued to unfold as it has been identified in a large number of vital metalloproteins, as an allosteric component and as a cofactor for catalytic activity. These proteins perform numerous important roles in the body, relating to the maintenance of immune function, neural function, bone health, arterial compliance, haemostasis, and protection against oxidative and inflammatory damage. However, the accurate assessment of copper status is problematic. Functional copper status is the product of many interacting dietary and lifestyle factors, and an adequate marker of body copper status has yet to be identified. Accurate measurement of dietary copper intake is difficult because while a number of dietary factors are known to limit...

Increased Infectious Disease Morbidity and Mortality

Large community-based clinical trials of vitamin A supplementation in Tamil Nadu, Nepal, and Ghana show that vitamin A supplemention reduced mortality from diarrheal disease but not pneumonia in preschool children (478,479). Vitamin A may reduce the morbidity of diarrheal disease through restoration of gut integrity (480) and enhancement of immune function (440,477). Urinary losses of vitamin A during diarrhea may be substantial in some children (481,482), and persistent diarrhea may reduce the bioavailability of vitamin A (483). Vitamin A supplementation (60 mg retinol equivalent RE ) reduced morbidity in children with acute shigellosis (484) but the effects of vitamin A supplementation on other specific diarrheal pathogens has not been completely clarified.

HIV Infection and Acquired Immunodeficiency Syndrome AIDS

AIDS is caused by the human immunodeficiency virus (HIV). It can be transmitted during unprotected sex, from contaminated needles shared by intravenous drug users, and from a pregnant mother to her baby. HIV invades white blood cells (T cells), multiplies, and then destroys the cells. As T cell counts fall, the cellular immune response weakens, increasing vulnerability to infection and cancer. Many people infected with HIV carry the virus for years without developing AIDS only about one in four HIV-infected people develop AIDS in the first 5 years after initial infection. Many remain healthy carriers of HIV, while others progress quickly to AIDS. In HIV disease, a critical determinant of progression is nutritional status. A combination of carefully selected diet, prudent micronutrient supplementation, moderate exercise, and a supportive social environment can maintain optimum immune function and, along with effective drug therapy, can slow progression of the disease.21-23

Mechanism of Action

Substrate for cholesterol synthesis.4 It is clear that HMB is converted to HMG-CoA in the cytosol, which can be used for cholesterol synthesis in cells.4 In all cells, cholesterol is needed for the synthesis of new cell membranes as well as the repair of damaged membranes in maintaining proper cell function and growth.4344 Certain cells, such as muscle cells, require de novo synthesis of cholesterol for cell cholesterol functions. Therefore, during periods of increased stress on cells, such as occurs in muscle during intense exercise, the demand for cholesterol for growth or repair of cellular membranes may exceed that which can be made through normal endogenous production from available cellular HMG-CoA. Thus, supplemental HMB may help meet an increased demand for and maintain maximal cell function by supplying intracellular HMG-CoA for cholesterol synthesis. The cholesterol can then be used to build and stabilize muscle cell membranes. This theory is supported by observations on...

Consequences of inadequate fat intake on the healing wound

Healthy humans have the capacity to thrive on very diverse combinations and ratios of protein, carbohydrate, and fat. The same is basically true for the patient with a healing wound so long as energy requirements are adequately met. As discussed above, wound healing will occur for some wounds even in the presence of essential fatty acid deficiency. Wounds due to surgery without underlying trauma, or lacerations to cutaneous tissue appear to heal well independent of nutrition, although inadequate nutrition prior to surgery is a risk factor for a poor surgical outcome.132 On the other hand, the healing of pressure sores ulcers and burns appears to be more sensitive to nutritional status.133 Clearly, there are different mechanisms at play for these different types of wounds. The first question, though, is under what scenario would there be inadequate fat intake One likely cause is fat malabsorption. Fat malabsorption can be idiopathic, due to a number of diseases,134-136 or can be a...

Roles of Apoptosis in Health and Disease

Involution of the thymus has long been recognized as a sensitive marker of malnutrition (Prentice, 1999) and impaired immune function. Thymocytes from young rats made severely malnourished by doubling the number of young suckling each dam had seven times higher rates of spontaneous apoptosis compared with those from well-fed controls (Ortiz et al., 2001). This greater rate of apoptosis may be responsible for the atrophy of the thymus in malnutrition (Ortiz et al., 2001), with serious consequences for both short- and long-term health (Moore et al., 1997). T-lymphocyte homeostasis occurs as a balance between apoptosis, mediated by local concentrations of interleukin-2 (IL-2), and proliferation in response to diverse antigens (Lenardo etal., 1999) including those from food. Nur77 is one of a pair of orphan nuclear receptors (the other is Nurr1), which hetero-dimerizes with the nuclear receptor retinoid X receptor (RXR) to activate gene transcription after binding retinoic acid (the...

Bad Cardio vs Good Cardio

To summarize, some of the potential benefits of variable cyclic training compared to steady state endurance training are as follows improved cardiovascular health, increased anti-oxidant protection, improved immune function, reduced risk for joint wear and tear, reduced muscle wasting, increased residual metabolic rate following exercise, and an increased capacity for the heart to handle life's every day stressors. There are many ways you can reap the benefits of stop-and-go or variable intensity physical training. One of the absolute most effective forms of

Immune Suppression and Inflammation

Vitamin A modulates many different aspects of immune function, both nonspecific (innate) immunity (i.e., maintenance of mucosal surfaces, natural killer (NK) cell activity, and phagocytosis) and specific (adaptive) immunity (i.e., generation of antibody responses). Some aspects of immunity are not affected by vitamin A deficiency. Much of our knowledge of vitamin A and immune function is based on experimental animal studies involving mice, rats, and chickens, and from in vitro studies involving modulation of specific cell lines with retinoids. The effects of vitamin A deficiency on immune function are summarized in Table 4. NK cells play a role in antiviral and antitumor immunity that is not major histocompatibility complex (MHC)-restricted, and NK cells are involved in the regulation of immune responses. Vitamin A deficiency appears to reduce both the number and activity of NK cells. In experimental animal models, vitamin A deficiency reduced the number of NK cells in the spleen...

Metabolism in the healing wound

Wound healing is a complex cascade of events that occur on the cellular and molecular level in response to injury. Platelets, polymorphonuclear (PMN) leukocytes, macrophages, and fibroblasts are recognized as the chief cell types of the immune system that respond at the site of injury in order to carry out their individual functions. As described previously, glutamine is an important fuel source for these rapidly dividing cells and is necessary for DNA and RNA replication prior to mitosis. There is evidence that there are considerable amounts of glutaminase activity in the skin of mice and rats that allow these tissues to utilize glutamine as an energy source 35 . These researchers were also able to demonstrate that glutaminase activity in the skin of the animals decreased as they aged. Alverdy et al. initially reported that TPN promotes bacterial translocation in the rat intestine. However, when rats were infused with glutamine-enriched TPN, bacterial translocation was dramatically...

Protein and Amino Acid Needs in Disease

Arginine is another nonessential amino acid with important properties for promoting immune system function. Arginine is the precursor for nitric oxide synthesis ( 186) and has been proposed as a nutrient for altering immune function and improving wound healing ( 187, 188). We believe that adequate ornithine is synthesized to maintain arginine supplies under normal conditions, but we do not know whether additional demands for arginine can be met endogenously or whether arginine becomes a conditionally indispensable nutrient. For example, Yu et al. (189) used stable isotope tracers to measure arginine kinetics in pediatric burn patients and determined little net de novo arginine synthesis, suggesting that under conditions of burn injury, insufficient arginine is made to meet the body's presumed increased need when the immune system is under challenge.

Amino Acids as Metabolic Regulators

During gestation there is a window of time when the embryo and fetus are susceptible to maternal protein intake. Low protein intake by rat dams during the pre-implantation period reprogrammes the physiology and metabolism of the fetus resulting in reduced postnatal growth rate, compromised immune function and the development of impaired glucose tolerance and insulin resistance in later life (Metges, 2001). Dietary lysine sufficiency during gestation-lactation of first-litter sows affects maternal weight loss, sow lactation and piglet growth, and interestingly, the added lysine results in an additional (10.7 vs. 9.6) piglet born alive in the subsequent mating (Tritton et ai, 1996). By contrast, in adolescent pregnant sheep, where the drive towards maternal tissue growth is still considerable, higher intakes favour partition of nutrients towards maternal tissues, rather than towards the fetal-placental compartment (Wallace, 2000). In adult ewes, maternal protein restriction of 30...

Healthrelated roles of Pcarotene

The mechanism for the increased risk associated with b-carotene supplementation in smokers is unclear. One suggestion is that the subjects of the studies already had a 'high risk' of developing lung cancer and many might have had undetected tumours at the start. The stage of carcinogenesis that b-carotene might affect is not known but if mediated by the immune system the effect might be at the promotional stages preceding the formation of a malignant tumour (Hughes, 2001). The immune system appears to be particularly sensitive to oxidative stress. Immune cells rely heavily on cell-to-cell communication, particularly via membrane bound receptors, to work effectively. Cell membranes are rich in polyun-saturated fatty acids and if peroxidised, can lead to a loss of membrane integrity, altered membrane fluidity and result in alterations in intracellular signalling and cell function. It has been shown that exposure to reactive oxygen species (ROS) can lead to a reduction in cell-membrane...

Specific aspects of fat needs

The 35 or so of energy provided by dietary fat refers only to the triglycerides found in our foods. High-performing athletes typically consume 20 to 25 fat, but they make certain that they get enough unsaturated fats because these fats, especially the omega-3 fatty acids, are generally thought to support immune function and keep athletes from catching common colds and nagging infections.

Fruits And Vegetables A Population Studies

A host of cancer-preventive and cardio-protective phytochemicals have been identified in these foods (see Table 14.1).21 Some of these phy-tochemicals may reduce the risk of cardiovascular disease by improving blood flow, inhibiting LDL oxidation, inhibiting platelet aggregation, interfering with cholesterol absorption and modulating cholesterol metabolism. The phytochemicals effectively involved in these processes include the carotenoids, flavonoids, tocotrienols, terpenoids, isoflavones, phytosterols, and various sulfur compounds from the Allium herbs. Furthermore, many of these phytochemicals block various hormone actions and metabolic pathways that are associated with the development of cancer stimulate the immune system block the formation of adducts between DNA and a carcinogen induce phase I enzymes (such as cytochrome P-450) and phase II enzymes (such as glutathione-S-transferase) and have antioxidant activity.1,11,20,22-28 Citrus fruits contain a variety of carotenoids. Pink...

Micronutrient Supplementation for Older Adults

Micronutrient supplementation is particularly beneficial in older age groups because many older people eat less and are less able to absorb micronutrients from foods.22 Moreover, in older adults even mild micronutrient deficiencies can weaken the immune system and impair memory and concentration. Together with eating a well-balanced diet, maintaining a lean body shape, and keeping physically active, micronutrient supplementation can be a powerful tool to maintain function in later years.