A Mechanism of the Vitamin-Sparing Effect of Antibiotics

Abstract

The growth of chicks fed synthetic diets containing limiting amounts of folic acid was increased by supplementing the diets with antibiotics. This increase in growth was accompanied by the appearance of one or more coliforms in the ileum and duodenum contents that produced increased amounts of extracellular folic acid. This change was apparent in two days in the ileum contents of 4-week-old chicks. It was also observed that the increased folic acid production was correlated with increased liver folic acid, but there was no change in the concentration of intestinal folic acid. These results explain at least in part the mechanism by which antibiotics spare vitamins for the chick.