brewer’s yeast /bro̅o̅″ərz/ [ME, brewen, to boil, yest, foam] , a preparation containing the dried pulverized cells of a yeast, such as Saccharomyces cerevisiae, that is used as a leavening agent and as a dietary supplement. It is one of the best sources of the B complex vitamins and a rich source of many minerals and a high grade of protein.
