The more processed the food, the more likely it is to contain free glutamates. Monosodium glutamate (MSG), a food additive used as a flavour enhancer, is the most common. The Food and Drug Administration (FDA) has declared MSG an ingredient that is "generally recognised as safe."
Whether or not MSG is healthy is another matter. A University of North Carolina study, published in the August 2008 issue of Obesity, links MSG to weight gain.
Glutamates are natural components of food, but free glutamates may cause allergic reactions, according to anecdotal evidence. Reported reactions include headache, flushing, sweating, and heart palpitations. For that reason, the FDA requires that it be listed on food labels.
When grocery shopping, always read the labels to find out if a food contains ingredients that contain free glutamates. In the U.S., MSG is referred to as umami, MSG, glutamate or free glutamic acid. Japanese food products refer to it as Ajinomoto and in China it is called wie jing. In Europe, it is E621. Other ingredients to look for are soy protein, hydrolyzed protein, wheat gluten, malted barley, autolyzed yeast, whey, milk powder or casein.
Some foods contain excessive amounts of glutamates. Soy protein is one of these, used in making vegetarian foods, baked goods and hot dogs. Hydrolyzed protein, another, can be fund in canned tuna, self-basting pastry and canned and dried soups. Powdered milk also contains high amounts, and is used to make low-fat (skim, 1%, 2%) milk products and baked goods. So do ultra-pasteurised dairy products, cheeses, cream, and half and half (with carageenan added.)
Any powdered, dried food mixes, as included in boxed dinners and packaged seasoning mixtures, will have a high amount of free glutamates, Snack foods, like flavoured potato and tortilla chips or flavoured jerky, are also high in MSG.
Some fresh foods, including over ripe tomatoes, Parmesan cheese and mushrooms, are naturally high in free glutamate.
The vast majority of fast food franchises use MSG. Foods that contain free glutamates in these establishments include chicken and sausage products, gravy, barbecue and other dipping sauces and salad dressings. French fries should also be avoided if an allergy is suspected, because the fry "seasonings" are infused in the oil.
Chinese restaurants have long used MSG to boost the flavour of their fare. Because the use of MSG is controversial, many Chinese restaurants have adjusted to MSG-free menus, unlike may of their restaurant counterparts.
Almost all restaurants liberally utilise free glutamates in their kitchens. Free glutamates occur in prepared stocks (bouillon cubes), Parmesan cheese, soups, Caesar salad, fish sauce, soy sauce, some deli meats, and most canned items.
Glutamates are the main source of flavour in miso, soy sauce, liquid aminos and hydrolyzed protein.
The artificial sweetener aspartame converts to glutamate in the system. Aspartame is used in diet sodas and desserts (e.g. gelatin), chewing gum, breath strips, children's and quick dissolve medicines, and chewable vitamins.