Selective retention of n-3 and n-6 fatty acids in human milk lipids in theface of increasing proportions of medium chain-length (C10-14) fatty acids

This paper reports the results of our analysis of the impact high levels of de novo fatty acids have on the proportions of essential and non-essential fatty acids in human milk lipids. The data for seven fatty acids (linoleic , alpha-linolenic, arachidonic (AA), docosahexaenoic (DHA), palmitic, stear ic and oleic) were derived from several studies conducted in Nigeria. The p roportion by weight of each of these fatty acids was plotted versus the pro portion of C10-14 fatty acids. As the proportion of C10-14 fatty acids incr eased from 15 to 65%, there was not a proportional decrease in the percenta ges of all seven fatty acids, but, instead, preferential incorporation of t he essential fatty acids, AA and DHA into the triacylglycerol component of the milk. At the same time, the proportions of stearic and oleic acid decli ned by 69% and 86%, respectively. However, the proportions of linoleic acid , palmitic acid, DHA, AA and ol-linolenic acid, in milk lipids decreased by only 44%, 40%, 39%, 28% and 2.3%, respectively. These observations indicat e that as the contribution of C10-14 fatty acids increases, essential fatty acids are preferentially incorporated into milk triacylglycerols at the ex pense of oleic acid and stearic acid. (C) 1999 Harcourt Publishers Ltd.