Evidence in man for different specialized intestinal transport mechanisms for riboflavin and thiamin

Abstract

Large oral doses of riboflavin and thiamin do not affect the absorption of one another in man. The absorption of a large dose of riboflavin is much greater when given after breakfast than on an empty stomach, whereas the extent of absorption of thiamin is not affected significantly by food. Although riboflavin and thiamin are absorbed by saturable intestinal transport mechanisms and are both phosphorylated during absorption, the results of this investigation suggest that the two vitamins do not share a common specialized absorption pathway.