Essential Long-chain Fatty Acids Research Articles

Quantitative changes in long-chain fatty acids during fetal and early postnatal development in rats

The quantitative importance of triacylglycerol as a source of total essential fatty acids during early postnatal development is reported in the accompanying article. Our objective here was to measure the quantitative changes in individual long-chain fatty acids in specific lipid classes of the carcass, liver, and brain of the developing rat mainly to describe the relative accumulation of long-chain vs. precursor fatty acids. Fatty acids in carcass phosphatidylcholine (micrograms/g) were lower at fetal days 18-21 than at either fetal day 15 or postnatal days +3 to +9. Individual long-chain fatty acids in liver phosphatidylcholine and phosphatidylethanolamine increased markedly by day +3 postnatally, whereas in brain phosphatidylethanolamine, the postnatal increase was delayed to between days +6 and +9. Fatty acids in carcass and liver triacylglycerols increased quantitatively by 10- to 300-fold from fetal day 21 to postnatal day +3 with amounts of both arachidonic and docosahexaenoic acid equaling linoleic acid. The ratios of linoleic and alpha-linolenic acids to respective long-chain products were significantly higher in triacylglycerols, whereas that of stearic to oleic acid was higher in phospholipids. We conclude that, during early postnatal life, oleic, linoleic, and alpha-linolenic acids are required in quantitatively greater amounts in triacylglycerols, whereas stearic acid and long-chain essential fatty acids are required in phospholipids.

Lipid composition and lipolytic activities in milk from a patient with homozygous familial hypobetalipoproteinemia

We have investigated the composition of breast milk from a patient with abetalipoproteinemia. Activity level and specific activity of lipoprotein lipase in milk samples obtained at 0.5 and 3 mo postpartum were higher than those found in normal milk; activity of bile salt-activated lipase was found to be higher in the milk at 6 mo postpartum than in normal milk but average specific activity of this enzyme in milk samples was not increased. Except for higher protein content of patient’s milk, there was no apparent abnormality in the protein pattern as determined by SDS-polyacrylamide gel electrophoresis. Lipid analysis indicated a shift in the molecular weight distribution of triglycerides, which favored lower molecular weight forms and reflected an increase in medium-chain and a major decrease in long-chain essential fatty acids (omega 6 and omega 3) in milk triglycerides.

Essential fatty acid requirements in infancy

The view expressed by Cuthbertson that essential fatty acid needs of human infants have been overestimated is contested. In our view Cuthbertson's assessment of essential fatty acid requirements of infants is too low because 1) consideration of the omega3 fatty acids is omitted; 2) the biological value of long-chain essential fatty acids is wrongly assessed; and 3) the significance of variations in composition of random human milk samples is misunderstood.