PALM OIL IN LIPID-METABOLISM

Historically, research relating to effects of edible oils has involved diets in which the oils under study were the only ones fed and in which one oil was always totally substituted for another. While the results thus obtained are valid considering the type of experiment they do not reflect effects of fats or oils as they are normally used. Using those modalities, various authors arrived at formulae for predicting plasma cholesterol changes based on alterations in dietary fat and cholesterol. These formulae proved to have utility although one study concluded that palmitic acid was the most hypercholestorelemic fatty acid and another concluded that it was myristic. In both sets of studies stearic acid did not fit the formulation. It is of interest that recent work has suggested that oleic acid, which had been thought of as neutral, possesses hypocholesterolemic properties. Studies carried out on the basis of total substitution and often using formula diets have shown, generally, that substitution of any formula for ordinary diet may be hypocholestorelemic and that the effects on plasma cholesterol in man are predictable based on fatty acid spectrum. It is noteworthy that in comparing coconut, beef tallow and safflower oil in real diets one study concluded that beef tallow (whose fatty acid pattern resembles that of palm oil) could not be regarded as a saturated fat. Recent data from experiments in which palm oil has been fed as part of a diet have suggested that it may not exhibit hypercholeserolemic properties in man. Some investigators have devised a variety of oil mixes to provide fats of a range of different fatty acids which fats were fed to three different strains of monkeys and showed that fats rich in lauric or myristic acid were significantly more cholesterolemic than those containing high levels of palmitic acid. For example, the fat mix containing 23% palmitic acid and 1% lauric plus myristic acid gave total serum cholesterol levels 15% lower than the one containing 25% palmitic acid and 19% lauric plus myristic acid. The LDL/HDL cholesterol ratio of monkeys fed the first mix was 15% lower than that of monkeys fed the second. It is hoped that these experiments will set a new standard for dietary studies in which fats will be fed at levels consistent with their usual intake.