The Availability of Vitamins from Yeasts

Abstract

The degree of absorption of riboflavin of various yeasts from the digestive tract was judged by urinary excretions and, in some experiments, fecal outputs, in studies utilizing human bioassay methods. There was little or no absorption of riboflavin from the fresh, raw yeast and only partial absorption from 2 dried yeasts which contained live cells. The destruction of the viability of the yeast in 3 samples resulted in release of the riboflavin rendering it available for absorption. Fecal riboflavin eliminations were in a general reciprocal relationship to urinary excretions of the vitamin, indicating that when urinary excretions showed failure of absorption of the yeast riboflavin, fecal riboflavin was increased. Both unabsorbed riboflavin and intestinal synthesis appeared to contribute to increases in fecal riboflavin.