The essential fatty acids α-linolenic acid (ALA, C18:3 (n-3)) and linoleic acid (LA, C18:2 (n-6)) are required for normal human metabolism. Chronic sub-clinical deficiencies of these fatty acids are increasingly being linked to major diseases such as cardiovascular disease and cancer. High intakes of n-3 fatty acids are especially important during pregnancy as they have been shown to be required for the developing central nervous system of the foetus. In particular the ALA metabolites docosahexanoic acid (DHA, C22:6 (n-3)) and eicosapentanoic acid (EPA, C20:5 (n-3)) appear to be beneficial. Although the conversion of ALA to DHA and EPA is possible in humans, the conversion is not efficient and probably sub-optimal during pregnancy. Therefore dietary sources of DHA and EPA, such as from certain fatty fish, have been shown to more effectively raise plasma levels.
Research has established that maternal fatty acid composition is associated with foetal neuronal development. However, less is know about how maternal dietary fatty acid composition may affect other aspects of development. To investigate the association between maternal fatty acid composition and subsequent childhood obesity at age 3, researchers1 measured the mid-pregnancy fatty acid intakes, plasma fatty acids and umbilical cord plasma fatty acid concentrations of 1120 pregnant women. Regression analysis was then used to examine the independent associations between n-3 and n-6 fatty acids with obesity. The results showed that for every standard deviation increase in dietary and umbilical cord plasma DHA and EPA, there was a reduction in subscapula and tricep skin fold measurement and a lower odds of obesity. In addition, a higher ratio of n-6 to n-3 fatty acids in the umbilical cord plasma was associated with higher skin fold readings and odds of obesity.
These result support the cell culture and animal study data that suggests that early exposure to long chain polyunsaturated fatty acid can influence adipose tissue development. In particular, exposure to the n-6 fatty acid arachidonic acid (AA, C20:4 (n-6)) may promote adipocyte formation whereas exposure to DHA may block this process. Administration of n-6 fatty acids to pregnant rats also increases the body weight of their offspring when compared to the administration of n-6 and n-3 fatty acids, perhaps due to changes in leptin concentrations. Taken as a whole it might be supposed that increasing the fat cell number during early development may have a carry on effect to adulthood and increase the chance of obesity, and the results of this study are evidence of this. Interestingly, these results did not find an association between maternal plasma fatty acid composition and childhood obesity.
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