Dietary Constituents which may Influence the Use of Food Cholesterol I. Eggs: Biotin and Avidin

Abstract

Varying degrees of biotin deficiency were produced in young rats by feeding otherwise adequate “purified” diets made high in cholesterol by adding dried whole egg or by adding cholesterol, as such, with dried egg white. These diets furnished 20 to 25% protein and about 13.5% fat. When supplemented with ample biotin, they produced, in control rats, liver fatty acid values one and one-half to three times, and total liver cholesterol values 6 to 8 times, as high as those of rats fed similar adequate cholesterol-free diets. Most of the increase in cholesterol was in the esterified fraction. Biotin-deficient rats fed the egg diets high in cholesterol failed to store excess liver cholesterol ester, even when they maintained nearly normal food intakes. Loss of subcutaneous and visceral fat occurred at the same time. When rats were transferred from an adequate diet which had produced high liver cholesterol storage to and avidin-rich diet without cholesterol, it could not be clearly shown that the avidin increased the rate of liver lipid depletion. Transfer to an avidin-rich diet containing cholesterol did, however, result in a marked decrease in liver cholesterol ester, in spite of a continued high cholesterol intake. The possible relationship of biotin supply to the ability of the animal to esterify and store fatty acid as well as cholesterol is discussed.