On the origin of animal ergothioneine.

Studies in this Laboratory with isotope-labeled compounds have given no evidence for the synthesis of ergothioneine by the rat, chicken, guinea pig, or human (1). On the other hand Heath and coworkers (2) have concluded from similar experiments that the boar does synthesize ergothioneine. We now report the results of studies on a young pig, in which we find no evidence for ergothioneine synthesis. Closely related to the question of ergothioneine synthesis by animals is the effect of dietary constituents on the levels of blood ergothioneine. Eagles and Vars (3) several years ago showed that diets containing corn led to increased blood ergothioneine in pigs, and Potter and Franke (4) observed similar effects with rats. In contrast, Hunter (5) was unable to find any marked effect of corn diets on blood ergothioneine in either pigs or rats. Moreover, several attempts to identify ergothioneine as a constituent of corn or other plant material have failed (5-7). In this paper we present evidence to show that corn can serve as a dietary precursor of blood ergothioneine in rats and also that the dietary level of ergothioneine required to produce this effect is so small that it may well explain failures to detect ergothioneine in plant material.