Constancy of the fluidity of the milk lipids of three different human populations

Abstract

Maintaining a proper fluid character of human milk requires that the triglycerides be liquid. The mean melting points (MMPs) of milk lipids were determined using the mol percentages and melting points of the constituent fatty acids of the lipids in milk from three different ethnic groups in Nigeria and Nepal. The MMPs of the milk lipids of Fulani (n = 34) and Kanuri (n = 89) women in northern Nigeria and Nepalese women (n = 48) were 35.4°C, 35.5°C, and 35.8°C, respectively (mean, 35.6°C). We also tested the correlation between MMP and the mol% of individual fatty acids. The strongest correlations were observed with lauric acid, oleic acid, linoleic acid and arachidonic acid. The results indicate that the fluidity of the lipid fraction of milk is maintained at 2–3°C below normal body temperature and raises interesting questions about the mechanism(s) by which the mammary gland regulates the fatty acid composition of the triglycerides it produces and secretes into milk.