It is a common misconception that monosodium glutamate (MSG) is bad and must be avoided. That is not exactly true, MSG is a naturally occurring substance found in foods like tomatoes, mushrooms, and more. It was first isolated and presented in pure powder form in 1909 and is a flavor enhancer that excites the fifth taste sense umami, like sugar enhances sweet.
Most good chefs use natural MSG by using tomatoes or mushrooms, etc., but many will also use the powder directly. MSG does not make you ill. It is found in seasonings, chips, many fast-food and pre-packaged foods, and sauces.