Effect of the Saturation of Fats Upon the Disposition of Ingested Cholesterol

Abstract

Rats were fed diets containing 30 per cent corn oil or lard with and without cholesterol and choline for four weeks. An attempt was made to learn more about the mechanism involved in changes in the blood cholesterol level associated with such diets by comparing the total amoung of sterol ingested with the recovered from the carcass tissues, fecal sterols and bile acids. Similar recoveries of activities were attempted in another group of animals given cholesterol-4-C14 after three weeks on similar diets. Sterol levels were found to be higher in the blood and carcass tissues of all animals on diets containing excessive amounts of cholesterol, even though only a limited amount of it appeared to be absorbed. The blood sterol level was elevated when dietary lard replaced the corn oil, whereas the tissue content appeared to be slightly increased by the intake of the more unsaturated fat. The amount of fecal sterols and bile acids or activity excreted by the rats on the corn oil and lard-containing diets was similar whereas in those on the low fat diet more activity was retained in the blood and carcasses and less was excreted. Lack of major changes in the disposition of ingested sterol in rats on the high fat diets prevents any definitite conclusions as to their role in the mechanism involved in blood cholesterol changes. The mass of conflicting reports attests to the increasing belief that this problem cannot be resolved without a more basic approach, probably at the cellular or subcellular level. However, the data obtained in this investigation and in many others are quite in line with the suggestion that the major changes in the blood cholesterol level may be caused by the ingested saturated fat rather than the unsaturated fat.