Chinese herbal supplements
Credit: Matej Pribelsky / Getty Images

The same year that it allowed l-tryptophan back on the market, the FDA recalled a range of Chinese herbal supplements produced by Herbal Science International, Inc. after they were found to contain ephedrine, aristolochic acid (associated with kidney disease) and, most troubling, human placenta. Whether or not consuming human placenta constitutes cannibalism is subject for debate, but either way, scientists say that eating it can transmit blood-borne diseases like hepatitis or HIV.