Define the Bioavailability of Riboflavin?
Riboflavin availability is sodium-dependent. Prolonged contact of dietary riboflavin with the absorptive surface of the intestinal mucosal cells increases the bioavailability of riboflavin. Intestinal uptake is increased in cellular riboflavin deficiency and decreased with a high riboflavin status. Diets high in psyllium gum decrease absorption whereas antacids, as well as, the mere presence of food increase absorption.
Metals such as copper, zinc and iron; drugs, caffeine and saccharin and vitamins such as incotinamide and ascorbic acid, tryptophan and urea form chelates and complexes with riboflavin and FMN and thus affect bioavailability. Pregnancy induces the formation of proteins which bind flavins. Bioavailability of riboflavin in foods, mostly as digestible flavocoenzymes, is excellent at nearly 95%, but absorption of the free vitamin is limited to about 27 mg per single meal or dose in an adult.