Comparison of Effects of Palmitic and Stearic Acids in the Diet on Serum Cholesterol in Man

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Abstract
Previous observations have indicated that stearic acid, in the diet of man, lacks the cholesterol-raising effect of other saturated fatty acids. A critical test of the lack of effect was made by comparing cocoa butter, the fat used in the original experiments, with a mixture of other fats matching cocoa butter in linoleic, oleic, palmitic, and stearic acids. These fatty acids were provided mainly by safflower oil, olive oil, palm oil, and totally hydrogenated soybean oil, respectively. The mixed fat was randomized to improve digestibility. Serum lipid levels of 30 men were identical when cocoa butter and the mixed fat were fed alternately for 18-day periods. This result shows that cocoa butter does not contain any special cholesterol-depressing substance. A second comparison was made between palm oil and a randomized fat mixture of the same four constituents. This mixture was so prepared as to match palm oil in its content of linoleic, oleic, and total saturated fatty acids. The mixture, however, provided daily 31 g stearic acid (10% of energy) more than palm oil, whereas palm oil provided 31 g more of palmitic acid daily. Serum cholesterol and serum phospholipids were higher by 24 and 13 mg/dl, respectively, when the men were eating the palm oil diet. Serum triglycerides were lower by 20 mg/dl. All these differences were statistically significant. The observed serum cholesterol difference agreed with that predicted, assuming that stearic acid, like oleic acid or mixed carbohydrate, has no effect on serum cholesterol concentration in man.