Maternal Fish Oil Intake and Insulin Resistance in the Offspring

The intake of fish oils during pregnancy increases the duration of pregnancy, reduces the incidence of premature delivery, and has other benefits for the neonates, but some harmful effects have been also reported including low levels of arachidonic acid, which is essential for intrauterine growth. The intake of fish oil has been claimed to reduce the risk factors of the metabolic syndrome, including insulin resistance and diabetes, although contradictory results have also been described. Data on the long-term effects of fish oil, consumed during the perinatal stages, on the glucose-insulin axis are scarce and variable in both humans and experimental animals. In 1-year-old male pups of rats with moderate intakes of fish oil during just the first half of pregnancy, insulin sensitivity was higher than in those from dams given identical treatment except that fish oil was replaced by one of four different oils. Different epigenetic DNA marks may explain the influence of dietary factors in early developmental stages on the risk of metabolic diseases in adulthood. There is also increasing evidence that those mechanisms may involve the modulation of noncoding small RNAs, and the increased insulin sensitivity in those adult pups of rats fed fish oil during early pregnancy has been related to changes in the expression of several microRNAs. In conclusion, the long-term effects of fish oil supplementation during the perinatal stage on insulin sensitivity are variable depending on the dose and time-window, and its epigenetic explanation seems to include decreases in the expression of microRNAs.