MSG, or monosodium glutamate, was isolated by scientists in 1907. Essentially a salt loaded with glutamic acid (an amino acid), MSG has been used as a flavor enhancer ever since it was patented in 1909. MSG produces a taste known as “umami,” which corresponds to the savory sensations found in meat, potatoes and rich greens like seaweed. In recent years a number of health concerns have arisen around MSG, most of which have been discounted by scientific studies. Regardless, some people still claim headaches from consumption of the additive, so it’s worth knowing what foods contain it.