Docosahexanoic acid (DHA, C22:6 (n-3)) is preferentially sequestered in human brain tissue, where it plays an important role in increasing neuronal membrane fluidity, improving synaptic transmission and possibly allows neurogenesis. Animal studies show that retinal rod photoreceptors, the cerebral cortex and synapses have particularly high concentrations of DHA. During pregnancy, the developing foetus receives its DHA from the mother via the umbilical cord, and once born is supplied with DHA from the mother’s milk. Research shows that babies fed breast milk have higher concentrations of DHA in their cerebral cortex than non-breast fed babies. Foetal conversion of alpha linolenic acid (ALA, C18:3 (n-3)) to DHA is very limited, and so infants rely on DHA from their mother’s milk. Evidence suggests that DHA improves infant brain development during pregnancy and the early years of life.
To investigate the effects of DHA on foetal brain development during pregnancy, pregnant women were fed a DHA containing functional food or a placebo from gestation week 24 until delivery1. The DHA was supplied in the form of a cereal bar that contained 1.7 grams fish oil containing 300 mg of DHA, and the placebo was an identical bar with corn oil substituted for the fish oil. Women consumed 3, 5 or 7 bars per week, with the average DHA consumption being 214 mg per day. Tests were then performed on infants after birth at age 9 months. The results showed that DHA treatment during pregnancy had a significant beneficial effect on the infants problem-solving ability. However, there was no effect between groups on the Fagan test of infant intelligence. Gestation and infant length was also significantly longer in the DHA group compared to the placebo group.
The amount of DHA administered in this double blind placebo controlled trial was deemed to be at a safe level for pregnant women. The results are interesting in that DHA appeared to increase the length of gestation period and also produced infants that were longer than the placebo counterparts. These results support animals studies and previous human trials that show a role for DHA in the development of the brain. The way the task were administered points to benefits of DHA in the processing of information, rather than improvements in motor control. The frontal cortex of the brain is required for problem solving in humans, and animal studies have shown that this area of the brain is particularly susceptible to DHA deficiency. Fish oil supplements appear therefore to provide the DHA necessary to allow proper brain development during pregnancy.
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