Despite evidence that no other manufacturer has ever made a problem batch, until 2005 the FDA recommended that L-tryptophan not be sold as a supplement. (Interestingly, it has made no effort to stop the sale of infant formula, most of which contains added L-tryptophan.)8With L-tryptophan unavailable, drugs such as Prozac, Zoloft, and Celexa have become our primary tools for combating the crippling