Although medium-chain triacylglycerols
(MCTs, composed of medium-chain fatty acids 8:0 and 10:0) have
long been described as having neutral effects on serum cholesterol
concentrations, experimental evidence supporting this claim is
limited. In a randomized, crossover, metabolic-ward study, we
compared the lipid effects of a natural food diet supplemented with
either MCTs, palm oil, or high oleic acid sunflower oil in nine
middle-aged men with mild hypercholesterolemia. Rather than
having a neutral effect, MCT oil produced total cholesterol concentrations
that were not significantly different from those produced
by palm oil (MCT oil: 5.87 ± 0.75 mmolIL; palm oil:
5.79 ± 0.72 mmol/L) but significantly higher than that produced
by high oleic acid sunflower oil (5.22 ± 0.52 mmollL). Lowdensity-lipoprotein
(LDL)-cholesterol concentrations paralleled
those of total cholesterol. MCT oil tended to result in higher
triacylglycerol concentrations than either palm oil or high oleic
acid sunflower oil, but this difference was not significant. There
were no differences in high-density-lipoprotein cholesterol concentrations.
The palmitic acid and total saturated fatty acid content
of plasma triacylglycerols in the MCT-oil diet was not significantly
different from that in the palm oil diet. On the basis of
percentage of energy, this study suggests that medium-chain fatty
acids have one-half the potency that palmitic acid has at raising
total and LDL-cholesterol concentrations.