n-3 and n-6 fatty acid enrichment by dietary fish oil and phospholipid sources in brain cortical areas and nonneural tissues of formula-fed piglets

Sufficient availability of both n-3 and n-6 long chain polyunsaturated fatt y acids (LCPUFA) is required for optimal structural and functional developm ent in infancy. The question has been raised as to whether infant formulae would benefit from enrichment with 20 and 22 carbon fatty acids. To address this issue, we determined the effect of fish oil and phospholipid (LCPUFA) sources on the fatty acid composition of brain cortical areas and nonneura l tissues of newborn piglets fed artificially for 2 wk. They were fed sow m ilk, a control formula, or the formula enriched with n-3 fatty acids from a low-20:5n-3 fish oil added at a high or a low concentration, or the formul a enriched with n-3 and n-6 fatty acids from either egg yolk- or pig brain- phospholipids. Both the fish oil- and the phospholipid-enriched formula pro duced significantly higher plasma phospholipid 22:6n-3 concentrations than did the control formula. The 22:6n-3 levels in the brain, hepatic, and inte stinal phospholipids were significantly correlated with plasma values, wher eas cardiac 22:6n-3 content appeared to follow a saturable dose-response. F eeding sow milk resulted in a much higher 20:4n-6 content in nonneural tiss ues than did feeding formula. Supplementation with egg phospholipid increas ed the 20:4n-6 content in the heart, red blood cells, plasma, and intestine in comparison to the control formula, while pig brain phospholipids exerte d this effect in the heart only. The addition of 4.5% fish oil in the formu la was associated with a decline in 20:4n-6 in the cortex, cerebellum, hear t, liver, and plasma phospholipids, whereas using this source at 1.5% limit ed the decline to the cerebellum, liver, and plasma. Whatever the dietary t reatment, the phosphatidylethanolamine 20:4n-6 level was 10-20% higher in t he brain temporal lobe than in the parietal, frontal, and occipital lobes i n the temporal robe by administering the formula enriched with egg or brain phospholipids. In conclusion, feeding egg phospholipids to neonatal pigs increased both th e 22:6n-3 content in the brain and the 20:4n-6 content in the temporal lobe cortex. This source also increased the 22:6n-3 levels in nonneural tissues with only minor alterations of 20:4n-6. These data support the notion that infant formulae should be supplemented with both 22:6n-3 and 20:4n-6 rathe r than with 22:6n-3 alone.