Monosodium glutamate is a common food additive and flavor enhancer used commercially for about a century. Like many food additives, it has been linked to a variety of health problems, including obesity, food addiction, migraines and other neurological conditions. Although it is classified as "generally regarded as safe" by the U.S. Food and Drug Administration, some researchers believe that MSG has toxic effects in the human body.
MSG is a sodium salt of glutamic acid, a naturally occurring amino acid. It was first isolated from seaweed extract by a Japanese researcher in 1907. Chefs soon realized that MSG provided a savory, taste-enhancing effect when added to foods. Shortly thereafter, MSG powder was patented by Ajinomoto Corporation of Japan in 1909 and sold as a flavor enhancer. MSG was introduced into the United States in 1947 under the name Ac'cent. MSG became infamous as a suspect agent causing various symptoms in people who ate at Chinese restaurants. Nevertheless, MSG is now used by virtually all fast food chains and is found in a wide variety of foodstuffs.
General Effects of MSG
MSG is a well-known compound in research circles used to fatten up rats for experimentation, because it dramatically increases insulin production. According to "Contemporary Nutrition," the food additive industry readily admits that MSG has addictive properties and can cause people to gain weight, but they justify its use by claiming that this can be beneficial to elderly persons who are sometimes malnourished. Glutamate, the main component of MSG, is the primary excitatory neurotransmitter in the brain, and it has been linked to neurological symptoms when taken in excess.
Potential Neurological Effects of MSG
Neurotransmitters, such as glutamate, are important for chemical communication in the brain, where they are very carefully balanced and managed. Excessive quantities of a neurotransmitter, however, can cause it to become an excitotoxin, a substance that over-excites cells to the point of damage. According to an article published in a 2001 issue of "Archives of Neurology," when the balance of glutamate is upset this substance can become neurotoxic, leading to enzymatic cascades resulting in cell death. Neurological conditions that some researchers claim may be associated with MSG include migraines, seizures, autism, attention deficit disorder, hyperactivity, Alzheimer's disease, Lou Gehrig's disease, multiple sclerosis and Parkinson's disease. However, according to a 2007 issue of the "European Journal of Clinical Nutrition," an international team of experts concluded that MSG was "harmless for the whole population." They declared that 16 mg/kg of body weight per day was the safe limit for MSG consumption.
Extent of MSG in Food
MSG is widespread, found in thousands of food products, particularly prepared stocks and soups, seasonings, condiments such as barbecue sauce and salad dressings, many canned foods, as well as in snack foods such as potato and tortilla chips. MSG is now rarely listed as such on ingredient labels because of the public's negative view of it. Instead, it can be listed as hydrolyzed vegetable or plant protein, plant protein extract, yeast extract or textured protein among other terms, according to "Nutrition and Public Health."