Though he stated in his letter that he wasn’t sure whether these symptoms were due to the alcohol, cigarettes, poor eating habits, or the MSG he’d consumed, the blame squarely landed on MSG.

MSG stands for monosodium glutamate. It’s the sodium salt of glutamic acid, a common amino acid naturally found in many foods and our bodies, says Stephani Johnson, D.C.N., R.D.N., a professor ...