An imbalance of dietary essential fatty acids retards behavioral development in mice

This study investigated the effects of an imbalance of dietary essential fatty acids on behavioral development. Pregnant and lactating mice were fed a diet with a very low (n-6):(n-3) ratio, in which the (n-6) and (n-3) fatty acids were provided solely as linoleic acid [LA, 18:2 (n-6)] and very high levels of docosahexaenoic acid [DHA, 22:6 (n-3)], respectively. The development of the pups was compared with that of pups of similar age and body weight that had been undernourished by rearing in large litters. On the day of conception (Day 0), pregnant B6D2F1 mice were assigned randomly to one of four dietary groups. Two of these groups were fed lab chow, and after birth varied in terms of the number of pups per litter, large (LgLIT) = 12, and normal (NmLIT) = 6. The remaining two groups both had six pups per litter, but varied in dietary (n-6):(n-3) ratio, low (LoRAT = 0.32) and normal (NmRAT = 4.0). On Day 32 postconception both the LgLIT and the LoRAT groups had lower body weights and were behaviorally retarded relative to their respective NmLIT and NmRAT controls. Nonetheless, there was some sparing of function in both these groups, as they were behaviorally advanced relative to younger animals of a similar body weight. These findings show that the growth retardation seen in the offspring of dams fed a diet with a low (n-6):(n-3) ratio and very high levels of DHA is accompanied by behavioral retardation of a similar degree to that seen in malnourished pups.