Effect of Combination of Several Foodstuffs on the Serum and Liver Lipids in Hypercholesterolemic Rats

Abstract

The present experiments were designed to find the desirable dietary composition for preventing cholesterolemia. Male Sprague-Dawley rats were fed hypercholesterolemic diets containing 15% polished rice to which several experimental foodstuffs were added singly or in combination. Determinations were carried out on the concentrations of major lipid fractions, lipid peroxide in the serum and liver, and high density lipoprotein cholesterol (HDL-cholesterol) in the serum. Results were as follows.
1) The serum cholesterol decreased in rats fed a diet with a single addition of safflower oil, whole soybean, okara (residues of tofu-soy milk processing) and shiitake (dried black mushrooms), respectively. Among them, safflower oil was the most effective. Combination of okara and shiitake showed the synergestic cumulative effect.
2) When the fish oil (sardine oil) containing highly unsaturated fatty acids was singly added to the diet, a marked decrease of serum cholesterol was observed. However, the combined addition of fish oil with okara or shiitake was not so effective as the single addition of fish oil.
3) Kombu (sea weed) was hardly effective for decreasing the serum and liver cholesterol concentrations. When other hypocholesterolemic foods were combined with kombu, kombu did not enhance the effectiveness of other foods.
4) The concentration of HDL-cholesterol in the serum of rats fed safflower oil or fish oil tended to elevate compared to the cholesterol-fed control group, and the ratio of HDL-cholesterol to total cholesterol in these groups were also significantly higher than those of other groups.
5) When rats were fed the diets containing fish oil, the lipid peroxide concentrations in the serum and liver were markedly elevated, but addition of okara and shiitake to a fish oil diet alleviated this effect.