N-3 Fatty Acid Requirements for Human Development

Overview

Polyunsaturated fatty acids known as n-3 fatty acids are essential dietary nutrients for humans, and are known to be important to reducing the risk of certain diseases, particularly those related to neural system, cardiovascular system and immune system. Among the different n-3 fatty acids, docosahexaenoic acid (DHA) is present in particularly high amounts in the brain and retina, and is accumulated in large amounts in these organs during the last trimester of fetal development and first few months after birth. The n-3 fatty acids are present in the diet as linolenic acid which is found in vegetable and seed oils, and as DHA which is only found in animal tissue fats, with fatty fish being the richest dietary source. Humans are able to convert linolenic acid to DHA, but the conversion is believed to be slow in human and possibly inadequate to support the needs for DHA for the developing brain. Information from our work and those of others has suggested that DHA is important during pregnancy, however specific evidence is lacking to show that the DHA status of pregnant women in low, or that improvement in the DHA status of Canadian women during pregnancy will have benefit to early infant an child development. There is no evidence that infants of vegans and vegetarians, or women who do not eat DHA are at risk for developmental delays. The purpose of this study is to investigate whether a dietary supplement of DHA during pregnancy has any effect on infant birth weight, or indices of infant growth, visual, mental and motor skill development.

This is a randomized, blinded prospective study with 2 groups: placebo and group supplemented with DHA. Women are randomized at 16 weeks gestation without knowledge of their dietary fatty acid intake. Only healthy women expecting to deliver a single infant with no known or anticipated maternal or fetal complications are enrolled. Maternal venous blood is collected at 16 and 36 weeks of gestation and used to assess the maternal DHA status and effect of DHA supplementation. Dietary information is collected at 16 and 36 weeks of gestation to determine usual fatty acid intakes. Following delivery, fetal cord blood is collected to assess transfer of DHA from mother to fetus. Breast milk samples are collected from all breast feeding mothers at 1 and 2 months postpartum. The mother -infant pairs are followed for 18 months. Measures include visual acuity, language, motor and mental development, and growth and dietary intakes.