Macronutrients

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Macronutrients provide the energy for all body functions as well as the major building blocks for all tissues and reparative processes (Table 1.2). As will be discussed in Chapter 2 and Chapter 3, carbohydrate and fat may both be used to support the energy needs of the organism, although certain cells may be obligate carbohydrate consumers. This is especially true in the healing wound, with a density of inflammatory cells and fibroblasts that use carbohydrate as an energy source.35 36 Studies suggest that, even when carbohydrates are readily available, a substantial percentage of the total energy needs are met by fat.37 These findings are discussed in greater detail in Chapter 3 and Chapter 11. In addition, fats provide the building blocks for the cell membrane and certain inflammatory mediators. Carbohydrates may minimize the burden for fat intake by providing substrate for fatty acid synthesis, except for essential fatty acids that must be obtained from dietary sources.

Protein is the third component of macronutrients. Amino acids provide the major structural building blocks of all proteins in the body, including collagen, the major protein of the healing wound. Amino acids are necessary for the cell membrane and enzymes and cytokine production in the healing wound. In the inflammatory and proliferative phases, amino acid requirements in the wound will be maximal due to the high level of enzymatic activity and the high rate of cell turnover.

Protein metabolism is closely interrelated to carbohydrate and fat metabolism. Glucose and fatty acid metabolites may be used as substrate for endogenous amino acid synthesis (Figure 1.4). Conversely, metabolites of amino acid breakdown may be deaminated to provide gluconeogenic precursors and substrate for fatty acid production. However, much like the fatty acids that cannot be synthesized by the human body, certain amino acids are essential or conditionally essential and must, therefore, be obtained through the diet. This concept is discussed in greater detail in Chapter 4.

Micronutrients

Micronutrients function primarily as cofactors in biochemical reactions and, as such, are critical to all of the activities of macronutrients. Protein synthesis cannot continue without adequate quantities of vitamin B6, zinc, and copper.26,37,38 Collagen synthesis will be impaired without vitamin C, iron, and copper. Carbohydrate utilization is impaired without chromium and manganese. Vitamin B12, folate, and zinc are essential for nucleic acid metabolism and, thus, are essential in the healing wound with rapid cellular proliferation.

TABLE 1.2

Function of Some Key Nutrients Involved in Wound Healing

Nutrient

Proteins

Carbohydrates Fats

Vitamins

Minerals

Specific Compound

Amino acids

Glucose Fatty acids Cholesterol

Vitamin C

Vitamin B complex

Vitamin A

Vitamin D

Vitamin E Vitamin K

Zinc

Iron

Copper

Contribution of Wound Healing

Needed for platelet function, neovascularization, lymphocyte formation, fibroblast proliferation, collagen synthesis, and wound remodeling Required for certain cell-mediated responses, including phagocytosis and intracellular killing of bacteria Gluconeogenic precursors Energy substrate of leukocytes and fibroblasts Serve as building blocks for prostaglandins, isoprostanes that are inflammatory mediators; energy source for some cell types Are constituents of triglycerides and fatty acids contained in cellular and subcellular membranes Hydroxylates proline and lysine in collagen synthesis Free radical scavenger

Is a necessary component of complement that functions in immune reactions and increases defenses to infection Serves as cofactor of enzyme systems

Required for antibody formation and white blood cell function, essential for nucleic acid metabolism Enhances epithelialization of cell membranes Enhances rate of collagen systhesis and cross-linking of newly formed collagen Antagonizes the inhibitory effects of glucocorticoids on cell membranes Necessary for absorption, transport, and metabolism of calcium

Indirectly affects phosphorus metabolism Free radical scavenger

Needed for synthesis of prothrombin and clotting factors VII, IX, and X Required for synthesis of calcium-binding protein Stabilizes cell membranes; enzyme cofactor Needed for cell mitosis and cell proliferation in wound repair

Needed for hydroxylation of proline and lysine in collagen synthesis Enhances bactericidal activity of leukocytes Hemoglobin oxygen transport to wound Integral part of the enzyme lysyloxidase, which catalyzes formation of stable collagen cross-links

Source: Modified from Schumann, D., Nurs. Clin. North Am., 14, 683, 1979. With permission.

Micronutrients are ubiquitous in a normal diet, and therefore, severe deficiencies are uncommon without pathologic stress. In many cases, they are only cofactors in chemical reactions, not altered or consumed, so they may ultimately be reutilized. However, with certain micronutrients, we have come to recognize the value of intake orders of magnitude greater than needed for cofactors of biochemical reactions. Vitamin C, for instance, in large quantities may be a useful free-radical scavenger, as discussed in greater detail in Chapter 8.3940 Vitamin A in large quantities may be useful to offset the adverse effects of corticosteroids on wound healing.3841 42 In Chapter 9, this is discussed in greater detail.

Nutrient Toxicity

Malnutrition may be defined as a state of nutrient deficiency or excess. This fact is often overlooked when providing nutrition, despite the fact that some of the adverse effects of nutrient excess are evident to everyone. Carbohydrate excess, for example, clearly may lead to a state of obesity, with the well-recognized risks of cardiovascular disease, diabetes, and shorter life expectancy. What is less obvious is that carbohydrate excess in the critically ill patient may also result in liver damage and the inability to wean from ventilators.26 In Chapter 2 and Chapter 11, this will be discussed in greater detail. Other nutrients, such as vitamin A, have the potential for toxicity that is even less obvious but equally dangerous.3842 This is discussed in greater detail in Chapter 9. It is apparent that in providing nutrition to stimulate healing, the caregiver cannot assume that "more is better."

In the chapters that follow, not only will the need for nutritional supplementation to optimize healing be evaluated, but also how to optimize that supplementation to avoid the consequences of nutrient excess will be addressed.

references

  1. Lawrence, W.T., Physiology of the acute wounds, Clin. Plast. Surg., 25, 321, 1998.
  2. Phillips, S.J., Physiology of wound healing and surgical wound care, ASAIO J., S2, 2000.
  3. Orgill, D. and Demling, R.H., Current concepts and approaches to wound healing, Crit. Care Med., 16, 899, 1988.
  4. Monaco, J.L. and Lawrence, W.T., Acute wound healing: An overview, Clin. Plast. Surg., 30, 2003.
  5. Ryan, G.B. and Manjo, G., Acute inflammation — a review, Am. J. Pathol., 86, 183, 1987.
  6. Wakefield, T.W., Hemostasis, in Surgery: Scientific Principals and Practice, 3rd ed., Greenfield, L.J., Mulholland, M.W., Oldham, K.T., Zelenock, G.B., and Lillemoe, K.D., Eds., Lippincott Williams & Wilkins, Philadelphia, 2001, chap. 4, p. 86.
  7. Clark, R.A. et al., Fibronectin and fibrin provide a provisional matrix for epidermal all migration during wound re-epithelization, J. Invest. Derm., 79, 264, 1982.
  8. Herndon, D.N., Nguten, T.T., and Gilphin, D.A., Growth factors; local and systemic, Arch. Surg, 128, 1227, 1993.
  9. Postlethwaite, A.E. et al., Induction of fibroblast chemotaxis by fibronectin, J. Exp. Med., 153, 494, 1981.
  10. Martin, P.M., Wooley, J.H., and McCluskey, J., Growth factors and cutaneous wound repair, Prog. Growth Factor Res., 4, 25, 1992.
  11. Barbul, A., Role of the immune system, in Wound Healing: Biochemical and Clinical Aspects, Cohen, I.K., Diegelmann, R.F., and Lindblad, W.B., Eds., W.B. Saunders, Philadelphia, 1992, chap. 17, p. 282.
  12. Robson, M.C. and Heggers, J.P., Eicosanoids, cytokines and free radicals, in Wound Healing: Biochemical and Clinical Aspects, Cohen, I.K., Diegelmann, R.F., and Lindblad, W.B., Eds., W.B. Saunders, Philadelphia, 1992, chap. 18, p. 292.
  13. Williams, J.Z. and Barbul, A., Nutrition and wound healing, Surg. Clin. N. Am., 83, 571, 2003.
  14. Morrow, J.D. et al., The isoprostanes: unique prostaglandin-like products of free-radical initiated lipid peroxidation, Drug Metab. Rev, 31, 117, 1999.
  15. Seppä, H. et al., Platelet derived growth factor chemotactic for fibroblasts, J. Cell. Biol., 92, 584, 1982.
  16. Postlethwaite, A.E. et al., Stimulation of the chemotactic migration of human fibroblasts by transforming growth factor-, J. Exp. Med., 165, 251, 1987.
  17. Pesciotta, D.M. and Olsen, B.R., The cell biology of collagen secretion, in Immu-nochemistry of the Extracellular Matrix, Furthmayer, H., Ed., CRC Press, Boca Raton, FL, 1992, chap. 2, p. 1.
  18. Miller, E.J., Collagen types: structure, distribution and functions, in Collagen Volume II: Biochemistry and Biomechanics, Nimni, Marcel E., Ed., CRC Press, Boca Raton, FL, 1988, p. 139.
  19. Diegelmann, R.F., Lindblad, W.J., and Cohen, I.K., Fibrogenic processes during tissue repair, in Collagen Volume II: Biochemistry and Biomechanics, Nimni, Marcel E., Ed., CRC Press, Boca Raton, FL, 1998, p. 113.
  20. Gospodarowicz, D., Newfield, G., Schweigerer, L., Fibroblast growth factor: structural and biologic properties, J. Cell. Physiol., 5, 15, 1987.
  21. Gospodarowicz, D., Abraham, J., and Schilling, J., Isolation and characterization of a vascular endothelial cell mitogen produced by pituitary derived follicular stellate cells, Proc. Natl. Acad. Sci. USA, 86, 7311, 1989.
  22. Werner, S. et al., Large induction of keratinocyte growth factor expression in the dermis during wound healing, Proc. Natl. Acad. Sci. USA, 89, 6896, 1992.
  23. Gabbianni, G., Ryan, G.B., and Majno, G., Presence of modified fibroblasts in granulation tissue and their possible role in wound contraction, Experientia, 27, 549, 1971.
  24. Molnar, J.A., Skin collagen turnover in healthy and protein calorie malnourished rats. Doctorate thesis, Massachusetts Institute of Technology, 1985.
  25. Cuthbertson, D.P., Observations on the disturbance of metabolism produced by injury to the limbs, Quart. J. Med., 1, 233, 1932.
  26. Molnar, J.A. and Burke, J.F., Nutritional aspects of surgical physiology, in Surgical Physiology, Burke, J.F., Ed., W.B. Saunders, Philadelphia, 1983.
  27. Albrina, J.E., Nutrition and wound healing, J. Parenteral and Enteral Nutr, 336, 1994.
  28. Clark, M., Plank, L.D., and Hill, G.L., Wound healing associated with severe surgical illness, World J. Surg., 24, 648, 2000.
  29. Cuthbertson, D.P., The disturbance of metabolism produced by bony and non-bony injury with notes on certain abnormal conditions of bone, Biochem. J., 24, 1244, 1930.
  30. Cuthbertson, D.P. and Tilstone, W.J., Nutrition of the injured, Am. J. Clin. Nutr., 24, 911, 1968.
  31. Molnar, J.A., Wolfe, R.R., and Burke, J.F., Burns: metabolism and nutritional therapy in thermal injury, in Nutritional Support of Medical Practice, 2nd ed., Schneider, H.A., Anderson, C.E., and Coursin, D.B., Eds., Harper & Row, Philadelphia, 1983 .
  32. Cuthbertson, D.P. et al., Effects of severity, nutrition, and environmental temperature on protein, potassium, zinc and creatinine, Brit. J. Surg., 59, 68, 1972.
  33. Bhattacharyya, A.K., Protein-energy malnutrition (kwashiorkor-marasmus syndrome): terminology, classification and evolution, Wld. Rev. Nutr. Diet, 47, 80, 1986.
  34. Ettinger, S., Macronutrients: carbohydrates, proteins and lipids, in Krause's Food Nutrition and Diet Therapy, 10th ed., Mahan, L., and Escott-Stump, S., Eds., W.B. Saunders, Philadelphia, 2000.
  35. Hunt, T.K., The physiology of wound healing, Ann. Emerg. Med., 17, 1265, 1988.
  36. Whitney, J.D. and Heitkemper, M.M., Modifying perfusion, nutrition, and stress to promote wound healing in patients with acute wounds, Heart and Lung, 28, 123, 1999.
  37. Smith, J.S., Austen, W.G., and Souba, W.W., Nutrition and metabolism, in Surgery: Scientific Principles and Practice, 3rd ed., Greenfield, L.J., Mullholland, M.J., and Oldham, K.T., Eds., Lippincott Williams & Wilkins, Philadelphia, 2001.
  38. Demling, R.A. and DeBiasse, M.A., Micronutrients in critical illness, Crit. Care Clin., 11, 651, 1995.
  39. Matsuda, T. et al., Effects of high dose vitamin C administration on postburn microvascular fluid and protein flux, J. Burn Care Rehabil., 14, 624, 1993.
  40. Tanaka, H. et al., Vitamin C administration reduces resuscitation fluid volume in severely burned patients. A randomized prospective study, Arch. of Surg., submitted for publication.
  41. Thompson, C.W., Nutrition and adult wound healing, Nutrition Week, January 18, 2003.
  42. Petry, J.J., Surgically significant nutritional supplements, Plast. Reconstr. Surg., 97, 233, 1996.

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