In the context of wound healing, the obvious role for essential fatty acids is on modulation of inflammation and the immune response.112-114 An examination of the literature in this area will uncover some conflicting data as to the benefits of essential rn-3 and rn-6 fatty acids in wound healing. One study in essential fatty acid deficient (EFAD) rats found that the healing rate of partial-thickness cutaneous burns was significantly decreased compared to controls.115 However, this study also found that healed single dorsal skin incisions were stronger in control animals, but there was no difference between the groups when ventral skin incisions with underlying fascial incisions were measured. These results would suggest that the type of wound or wound location and regional environment (adipose tissue?) may influence healing. Another study on cutaneous wound healing in EFAD rats concluded that essential fatty acids were not necessary for cutaneous wound repair.116 In this study, there was no difference in maximal breaking strength or cellular inflammatory infiltration when compared to controls. An additional cutaneous wound healing study found that rats fed a diet enriched in rn-3 fatty acids produced wounds that were weaker in tensile strength compared to those from rats fed a diet containing rn-6 fatty acids.117 Fish oil was found to inhibit connective tissue proliferation in a rat model of liver wound healing,118 but the effect could be blocked by treatment with the antioxidant a-lipoic acid. This latter result again raises the question of the role of oxidative stress in the wound and the susceptibility of essential fatty acids to lipid peroxidation. It is clear from many studies that there is a close relationship between antioxidants and lipid peroxidation in vivo. Antioxidants that have been shown to reduce lipid peroxidation and modify the effects of fatty acids include vitamins C119 and E,120 selenium compounds,121,122 and the previously mentioned a-lipoic acid.118 Therefore, to properly understand and interpret the data on the effects of essential fatty acids, the antioxidant status of the patient or the model system needs to be considered. To make conclusions about the effects of essential fatty acids, the stage of wound healing and the type of wound need to be considered. The data suggest that in the early stages of wound healing, the anti-inflammatory effects of rn-3 fatty acids or other lipid mixtures123 may delay wound healing. However, burn patients have lower levels of arachidonic acid and m-3 fatty acids in their plasma following burn injury,124 and supplementation with rn-3 fatty acids seems to be beneficial for these patients,125 or for those in a hypermetabolic state.126
The cardiovascular risk factors associated with saturated fatty acids are well documented. This lipid class is not metabolized to any bioactive molecules and is, therefore, considered to be more or less neutral to the inflammation process. Studies have shown that diets containing stearic acid had no effect on in vivo thromboxane
A2 or prostacyclin biosynthesis.127 When comparing the effects of diets enriched in lauric plus myristic acid or palamitic acid to stearic acid in healthy young men, it was found that palmitic acid increased factor VII coagulant activity compared to those enriched with stearic acid. However, stearic acid increased fibrinogen concentration compared to the lauric plus myristic acid diet.128 It is unknown if these modest affects on clotting factors could be a factor in the early stages of wound healing.
The monounsaturated fatty acids are an excellent source of energy and appear to provide modest benefits in improving plasma lipoprotein profiles in high risk groups. In one study in healthy young men, diets high in MuFA (33% of total fatty acids in the diet) resulted in reduced platelet aggregatory response compared to a moderate MuFA diet (16% of total fatty acids in the diet).129 MuFA may also be able to modify the lipolysis rates in adipocytes. Some research indicates that dietary MuFA may lower the antilipolytic activity of insulin better than PuFA. A study in rats demonstrated an increased baseline and adrenaline-stimulated lipolytic activity and a decreased antilipolytic capacity of insulin in animals with an increase in MuFAs in their tissues.130 Rats fed MuFAs have also been shown to have increased glycemic tolerance compared to those fed a diet containing saturated fatty acids. Rats fed MuFA had increased secretion of the antidiabetic hormone, glucagon-like peptide-1 (GLP-1), as determined by immunoreactive methods.131 These results suggest that MuFA may be beneficial as part of the nutrient regimen for diabetic patients.
Was this article helpful?
A time for giving and receiving, getting closer with the ones we love and marking the end of another year and all the eating also. We eat because the food is yummy and plentiful but we don't usually count calories at this time of year. This book will help you do just this.