Dietary reference intakes for macronutrients have recently been published.150 Significantly, for the first time these recommendations include amounts of ra-3 PuFA for infants as well as adults. For rn-6 PuFA, it is recommended that men between the ages of 19 and 50 years receive 17 g/d of linoleic acid and that women in the same age group receive 12 g/d. The requirements drop to 14 g/d for men older than
50 years of age and to 11 g/d for women over 50 years of age. For rn-3 PuFA, it is recommended that men older than 19 years of age receive 1.6 g/d of a-linolenic acid, and women older than 19 years of age receive 1.1 g/d. Based upon these amounts, the recommended m-6:m-3 ratio for men up to 50 years of age is approximately 10.6:1, and changes to 8.75:1 for men over age 50. For adult women up to 50 years of age, the ratio is 10.9:1, and it then changes to 10:1 for women over 50 years of age. Research on rn-6 and rn-3 PuFA has found that it is the ratio of these two essential fatty acid classes in the diet that determines the systemic and metabolic effects.1 In the past century, there was a large increase in the amount of rn-6 fatty acids found in the Western diet due to the increasing use of plant seed oils. The increased intake of these oils led to m-6:m-3 ratios in the Western diet in excess of 15:1.1 The new recommended levels for these PuFAs recognize the excess of ra-6 and the need for rn-3 PuFA, but the ratios may not be low enough to realize some of the therapeutic effects of rn-3 PuFA. For cardiovascular- and inflammatory-related diseases such as asthma and rheumatoid arthritis, m-6:m-3 PuFA ratios less than 5:1 have been shown to be beneficial. The optimal m-6:m-3 PuFA ratio for wound healing is unknown. However, these fatty acids could be used as adjuvants to the healing process by modulating inflammation if needed. The use of these nutrients will largely depend upon the nature of the wound, the stage in the healing process, and the existence of any underlying disease states. It is clear that in the early stages of wound healing, an adequate inflammatory response is needed to initiate the healing process, and ratios of m-6:m-3 less than 10:1 may not be advisable. During the proliferative and remodeling stages of wound healing, there may be benefits to varying the m-6:m-3 ratios or the type of PuFA, but research is still needed before any recommendations can be made. With respect to the other fatty acid classes, there are no recommended amounts in the new dietary reference intakes, as these are not considered essential nutrients. However, there are some general principles that can be followed. The first is that trans-fatty acids in the diet should be minimized, as there are no requirements or benefits, and likely only harmful effects.39 Saturated fatty acids are an excellent energy source, but there is no dietary requirement, because they can be synthesized endogenously from carbohydrate energy sources. Monounsaturated fatty acids may be a better alternative as a fat energy source, because they are readily utilized and do not have the negative cardiovascular affects associated with saturated fatty acids. Therefore, the current data suggest that the need for dietary lipids to supply the components for tissue growth and remodeling as well as energy is best met primarily by monounsaturated fatty acids with varying amounts of rn-6 and rn-3 PuFA. The best ratio of m-6:rn-3 PuFA to use as an adjuvant to the healing process remains to be determined. The amount of fat to include in treating wound patients needs to be determined in the context of energy expenditure and the nature of the wound.151
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