Synthesis of riboflavin by intestinal bacteria.

Abstract

The amounts of riboflavin, both free and esterified, excreted in urine and feces of an individual, fed for one week each either an ordinary, or a vegetable or a meat diet, containing approximately neccessary amounts of nutrients and vitamins, were examined.When the same ordinary diet is taken, the amounts of riboflavin excreted In urine and feces are relatively constant. It consists of about 70% of the free and 30% of the estersfied form both in urine and in feces. When vegetable diet is taken, the amount of urinary riboflavin does not change markedly, but that in the feces increases to about 5 times in a week, whereby the amount of feces increases to about 3 times. When the vegetable diet is changed into the ordinary one, a return to the initial state takes place within about 3 days. When the meat diet is taken, the urinary riboflavin rises remarkably, contrary to the vegetable one, but the fecal riboflavin decreases slightly. When the meat diet is changed into the ordinary one, the riboflavin content in the urine decreases rapidly.From the above, it can be concluded that vegetable diets enhance markedly the riboflavin synthesis by intestinal bacteria.