Effects of low and high fat diets varying in ratio of polyunsaturated to saturated fatty acids on biotin intakes and biotin in serum, red cells and urine of adult men

Abstract

Levels of biotin were determined in controlled modified fat diets and in serum, urine and red blood cells (RBC) of 30 men, 34–61 years old. Four diets of commonly eaten USA foods were fed: Diet I, 43% fat calories (FC), P/S 0.3; Diet II, 25% FC, P/S 0.3; Diet III, 43% FC, P/S 1.0; and Diet IV, 25% FC, P/S 1.0. All subjects ate a “stabilization” diet, which was identical to Diet I, for 3 weeks followin a 1-wk “free-living” pre-study period. Each of the 4 diets was then fed for two 6-wk periods. Biotin, determined by bioassay with Ochromonas danica, was significantly lower in the low fat diets (28 μg/day) than in the high fat diets (37–42 μg/day). Average serum biotin varied from 627 to 737 pg/ml with all diets, but the averages were lowest with the pre-study diet (636 pg/ml) and with Diet II (627 pg/ml), and all were higher than previously reported normal values of 485 pg/ml. Average urine biotin varied from 19 to 35 μg/24 hr and was lowest with the pre-study diet (19 μg/24 hr) and with the stabilization diet (I) 26 μg/24 hr). RBC biotin values averaged from 240 to 279 pg/ml with all diets, but were not significantly affected by diet. Correlations between biotin levels, blood lipids and fatty acids were evaluated. For all diets, there was a statistically significant correlation among urine, diet and serum biotin.