Docosahexaenoic acid (DHA, C22:6 (n-3)) is an omega-3 fatty acid that feeds into the omega-3 essential fatty acid pathway. Although not an essential fatty acid itself, as it can be synthesised from alpha linolenic acid (ALA, C18:3 (n-3)), DHA is increasingly being shown to possess some unique dietary properties that may in the future necessitate it being reclassified as conditionally essential. Omega-3 fatty acids have a number of functions in general including the formation of cellular signal molecules, eicosanoids. However, DHA also has specific roles that fall outside this general omega-3 function. In particular, DHA is required for the formation of the central nervous system during foetal and infant growth. In this respect, the foetus is supplied with DHA directly through the mother’s placenta, and the infant receives DHA from the mother’s milk. Evidence suggests that those mother’s that consume DHA have infants that are more intelligent and more able to withstand disease compared to those mother’s who do not consume DHA.
The period following birth is very critical in the development of infants. During this time the central nervous system adapts quickly to the surroundings and development is rapid. Supplying the infant with adequate nutrition to allow this development is therefore highly important. For DHA to be useful in this regard it must be able to be absorbed by the mother and pass to her milk to allow it in turn to be transferred to the infant. Studies have investigated the ability of DHA to accumulate in mother’s milk and evidence shows that DHA readily passes from the mother’s circulation to the milk. For example, in one study1, researchers measured the transfer of radiolabeled DHA from the diet to the milk in nursing mothers who were fed a supplement of 200 mg of DHA per day. After 2 weeks of supplementation, the DHA content of the milk in the DHA fed mother increased 2-fold compared to another group receiving a placebo. Other fatty acids in the placebo and DHA supplements also transferred into the milk.
Dr Robert Barrington’s Comments: This study shows that DHA in the Mother’s diet is effectively passed to the infant during early life. The ability of mothers to accumulate DHA in their milk may explain the superior health demonstrated by those infants who are breast fed compared to those that are formula fed. Studies attest to the lesser development of formula fed infants compared to breastfed infants, particularly with regard to the resistance to disease and to intelligence. The lack of DHA in formula milk is a result of long chain fatty acids propensity to spoil during storage, and so they are not included in formula milk. Breast feeding in combination with a healthy intake of DHA containing foods or DHA supplements is the best way to ensure adequate DHA for the growing infant. If DHA is obtained from fish or fish supplements it is important to obtain fish that are free of toxins and pollutants as these can also easily be passed to the growing infant.
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