Essential Fatty Acids in Infant Nutrition: Lessons and Limitations from Animal Studies in Relation to Studies on Infant Fatty Acid Requirements.
Essential Fatty Acids in Infant Nutrition: Lessons and Limitations from Animal Studies in Relation to Studies on Infant Fatty Acid Requirements.
Year: 2000
Authors: S Innis.
Publication Name: Am. J. Clin. Nutr.
Publication Details: Volume 71;238S.
Abstract:
There is uncertainty in the literature as to the levels, and which of, the n-6 and n-3 PUFAs are needed in infant diets. Animal studies have been very important in advancing knowledge about the metabolism and roles of PUFAs and the effects of specific dietary intakes on membrane composition and related function. The advantages of animal studies include rigid control of PUFA and other nutrient intakes and the degree, timing and duration of deficiency or excess, the absence of confounding environmental and clinical variables, the level of tissue analysis and testing procedures that cannot be performed in human studies. However there are some important differences among species in their nutrient requirements and metabolism. The author of this review suggests that the severity and duration of the dietary protocol must be considered before extrapolating results to humans. In this review, the author considers many of the major contributions made by animal studies to the understanding of EFA requirements during growth and development, and the limitations surrounding extrapolation of this data to humans. The review includes studies of animals fed diets deficient in n-3 PUFA, n-6 and n-3 PUFA requirements in animals, the transfer of maternal dietary PUFAs through breast milk to infants and animals fed dietary sources of the n-6 PUFA, arachidonic (AA) and the omega-3 PUFA, docosahexanoic (DHA) acids. Studies in rodents and nonhuman primates have shown that diets which were severely deficient in ALA result in altered visual function, neural system metabolism and behavioural problems. Studies on DHA and AA supplementation have suggested that brain and retinal concentrations of DHA plateau with ALA intakes of 0.7% of energy, however this intake is influenced by dietary LA intake. At high intakes of DHA, adverse effects on growth and function have been noted. In animals fed well-controlled diets, studies have established the dietary essentiality of LA and ALA. This research has also assisted in understanding the biochemical and physiologic roles of AA and DHA. Animal studies offer the opportunity to explore the reasons for both positive and adverse effects of oils high in n-3 fatty acids and the potential for avoiding these effects by cosupplementation with AA.
