Evidence is growing that the long-chain fatty acids from fish are beneficial to the health. Docosahexanoic acid (DHA, C22:6 (n-3)) and eicosapentanoic acid (EPA, C20:5 (n-3)) have been shown to play an important role in preventing inflammation caused by the pro-inflammatory arachidonic acid (AA, C20:4 (n-3)). The essential fatty acid alpha linolenic acid (ALA, C18:3 (n-3)) can be converted to DHA and EPA in humans but the conversion rate is limited. However, ALA appears to be beneficial in itself and may have separate physiological roles beyond its role as a precursor to longer chain fatty acids. Dietary linoleic acid (LA, C18:2 (n-3)) is also essential and one of its metabolites, dihomo-gamma linolenic acid (DGLA, C20:3 (n-6)) is a potent anti-inflammatory agent that has been shown to have potential benefits to inflammatory conditions of the skin and joints.
Adequate nutrition is known to be essential to foetal health, and research suggests that the fatty acid profiles of the mother may have an influence of birth weight and health of the child. In particular the concentrations of n-3, n-6 and trans fatty acids in the plasma of the mother may influence foetal growth and development. For example, adequate DHA levels are known to be essential for proper brain development. Researchers1 have investigated the association between maternal fatty acid profiles during early pregnancy and foetal growth. In the study, 12 373 pregnant women from Amsterdam donated blood for nutrient analysis at the 12th week of pregnancy and completed a questionnaire. Of these woman 4336 had their plasma phospholipids fatty acid concentrations measured. The weight of the children were then measured at birth and the small for gestation risk (SGA risk) calculated.
The results showed that low concentrations of the n-3 fatty acids, docosapentanoic acid (DPA, C22:5 (n-3)), EPA, ALA, DHA, and DGLA, combined with high concentrations of non-DGLA n-6 fatty acids, and the main dietary trans fatty acid (18:1 (n-9t)) were associated with lower birth weight. This reduction in birth weight was estimated to be -52 to -172 grams for the lightest infants compared to the mean weight. The association for lower birth weights remained even after adjustment for physiological and lifestyle factors. The results for SGA were similar to those of birth weight, with lower concentrations of n-3 fatty acids (except DHA and ALA) and DGLA, and higher concentration of non-DGLA n-6 fatty acids resulting in an increased risk of being small at gestation. Infants born to the 7% of women with the most adverse fatty acid profiles had children on average that were 125 grams lighter and twice as likely to be small for gestational age.