A lack of correlation among fatty acids associated with different lipid classes in human milk.

The fatty acids associated with triacylglycerol, cholesteryl ester, phosphatidylethanolamine, phosphatidylcholine and sphingomyelin in human milk were compared. Ten milk samples were selected for lipid class analysis based on their total lipid polyunsaturated/saturated fatty acid ratio (P/S ratio). The P/S ratio of the selected milk samples ranged from 0.3 to 0.8. Linoleic acid was the predominant fatty acid in milk to affect the P/S ratio. The percentage of linoleic acid in milk triacylglycerol was correlated (r = 0.84, P < 0.05) with the total milk lipid P/S ratio. Linoleic acid esterified to cholesterol was not correlated with total milk lipid P/S ratio but was correlated (r = -0.66, P < 0.05) with the quantity of lipid in the milk. Linoleic acid in the phospholipid classes did not correlate with shift in P/S ratio of the total milk lipid or linoleic acid content of other lipid classes.