Effect of Viscosity on Thiamine and Riboflavin Absorption in Man

Abstract

Thiamine and riboflavin are absorbed from the upper small intestine by specialized transport processes. It was thought that oral administration of these vitamins in viscous solution would affect their absorption, since a previous investigation in rats showed that viscous solutions decrease the absorption of drugs from the stomach and retard gastrointestinal transit. Contrary to expectations, oral administration of thiamine and riboflavin in 50 ml. of highly viscous methylcellulose solution (3400 cps. at a shear rate of 5.1 sec.-1) did not affect significantly the rate and extent of absorption of the two vitamins in healthy adult volunteers.