The influence of a maternal diet rich in linoleic acid on brain and retinal docosahexaenoic acid in the rat.

Female rats were given throughout pregnancy and lactation a semi-synthetic diet, in which the fat was provided entirely by a soft margarine rich in linoleic acid (18:2 omega 6) or by mixture of butter and lard, and the influence on the fatty acid composition of fetal and pup brain and retinal phosphoglycerides was studied. The percentage of docosahexaenoic acid (22:6 omega 3) was much lower but that of docosapentaenoic acid (22:5 omega 6) was correspondingly higher in the brains of the day-22 fetuses and the 21-d-old pups from the margarine group compared with those from the group given the animal fats. Similar changes were noted in the synaptosomal and retinal phosphoglycerides, being most marked in the ethanolamine phosphoglycerides. The remaining pups from two groups were weaned on day 21 post partum on to the same stock diet that contained preformed 22:6 omega 3. After 9 weeks of this diet, the differences between the two groups in the fatty acid composition of the brain phosphoglycerides were barely discernible. The percentage of 22:5 omega 6 had decreased and had been replaced by 22:6 omega 3. It is concluded that the consequences of consuming a diet rich in linoleic acid and almost devoid of 22:6 omega 3 on brain fatty acid composition deserve consideration in man.