Turnover of Individual Free Fatty Acids in Man

The use of tracer fatty acids in the study of free fatty acid (FFA) metabolism in man is reviewed in light of the present knowledge of the metabolism of individual FFA. The fractional turnovers of palmitic, stearic and oleic acids are very similar and close to the values reported for the total plasma FFA. The fractional turnover of the polyunsaturated arachidonic acid is higher and there is also a sex difference, women showing 70% higher values than men. Splanchnic fractional uptake differs considerably among the individual FFA, while muscle uptake is virtually independent of the chemical structure of the fatty acid. It is concluded that labeled oleic or palmitic acid can be used as tracers for the total FFA fraction when studying the whole body turnover in the postabsorptive state. In other situations, conclusions from result of tracer experiments should be limited to the particular fatty acid studied. For measurements of splanchnic FFA metabolism, no single fatty acid seems to be adequate as a tracer for the total FFA fraction.