This may be too Talebian a reaction, but isn't the track record of "take this-doesn't-occur-in-significant-quanities-in-food chemical and your health will improve" quite poor? Non-food chemicals are often very useful for acute interventions (e.g. antibiotics, chemotherapy), but at least in modern times, they almost always do more harm than good when taken long-term.

(To avoid getting sidetracked by chronic medicines that some people swear by, I'm directing this point more at non-food drugs that are designed to take people from normal health to great health rather than from a disease state back to normal.)