Kevin LoriaAugust. 26, 2014 Monosodium glutamate, more commonly known as MSG, gets a bad rap. People claim that it's a toxin that causes headaches and sweating, and that it leaves you feeling lethargic and flushed. The thing is, most research shows that that's not true at normal dietary levels. Despite its umami flavor boosting power, rumors have given MSG a reputation so bad that many Chinese restaurants frequently put up "No-MSG" signs to assuage customer's fear.