Monosodium glutamate (MSG) known as sodium glutamate and E621. MSG is white or off-white crystalline powder with a slight odor. It's found naturally in tomatoes and cheeses, and is added to many processed foods, including canned vegetables, soups, deli meats, and fast food.
The FDA considers MSG to be "generally recognized as safe" (GRAS), but some studies have questioned its long-term safety. For example, preclinical studies have found that MSG can cause: Cardiovascular toxicity, Increased oxidative stress in cardiac tissue, Increased levels of heart disease biomarkers, and Hepatotoxicity