The myth that MSG (monosodium glutamate) is bad for you comes from a letter a doctor wrote to the New England Journal of Medicine in 1968, where he coined the phrase "Chinese restaurant syndrome" and blamed a variety of symptoms including numbness and general weakness on MSG.

Further research has not backed him up.

The scientific consensus according the American Chemical Society is that "MSG can temporarily affect a select few when consumed in huge quantities on an empty stomach, but it's perfectly safe for the vast majority of people."

MSG is nothing more than a common amino acid with a sodium atom added. Eating a ton of food or tablespoons full of the salt could cause the general malaise attributed to the flavor enhancer, and the placebo effect is more than strong enough to account for the negative effects sometimes associated with MSG.