Dietary non-starch polysaccharides interact with cholesterol and fish oil in their effects on plasma lipids and hepatic lipoprotein receptor activity in rats.

Male rats were fed the non-starch polysaccharides pectin, methylcellulose or guar gum with corn oil or with 60% of the corn oil replaced by fish oil. They were also fed these diets with or without cholesterol (+ cholic acid). Plasma total cholesterol concentration was higher overall in rats fed cholesterol and lower in those fed fish oil or fish oil + cholesterol. Plasma triacylglycerols were lower in rats fed fish oil with or without cholesterol. Hepatic LDL receptor activity was higher overall in rats fed fish oil or fish oil + cholesterol than in those fed cholesterol. Liver HDL receptor was lower overall in rats fed fish oil or cholesterol. Type of non-starch polysaccharide influenced these dietary effects so that in cholesterol-fed rats plasma cholesterol was highest in those fed methylcellulose, intermediate in those fed guar gum and in those fed pectin was unchanged from concentrations in rats fed pectin without cholesterol. Fish oil feeding lowered plasma cholesterol concentration in rats fed pectin or methylcellulose but not in those fed guar gum. Plasma triacylglycerols were lower in rats fed fish oil and all three non-starch polysaccharides, but concentrations were similar in rats fed pectin + fish oil + cholesterol and in those fed pectin. In rats fed methylcellulose + cholesterol and any non-starch polysaccharide + fish oils, HDL receptor activity was uniformly lower than in rats fed pectin, methylcellulose or guar gum. Low density lipoprotein receptor activity was higher in rats fed pectin + fish oil or pectin + fish oil + cholesterol than in rats fed pectin.