Monosodium glutamate (MSG) is used as a flavor enhancer in a variety of foods prepared at home, in restaurants, and by food processors. Its use has become controversial in the past 30 years because of reports of adverse reactions in people who’ve eaten foods that contain MSG. Research on the role of glutamate–a group of chemicals that includes MSG–in the nervous system also has raised questions about the chemical’s safety.
The FASEB report identifies two groups of people who may develop a condition the report refers to as “MSG symptom complex.” One group is those who may be intolerant to MSG when eaten in a large quantity. The second is a group of people with severe, poorly controlled asthma. These people, in addition to being prone to MSG symptom complex, may suffer temporary worsening of asthmatic symptoms after consuming MSG. The MSG dosage that produced reactions in these people ranged from 0.5 grams to 2.5 grams.
MSG is the sodium salt of the amino acid glutamic acid and a form of glutamate. It is sold as a fine white crystal substance, similar in appearance to salt or sugar. It does not have a distinct taste of its own, and how it adds flavor to other foods is not fully understood. Many scientists believe that MSG stimulates glutamate receptors in the tongue to augment meat-like flavors.
Glutamate itself is in many living things: It is found naturally in our bodies and in protein-containing foods, such as cheese, milk, meat, peas, and mushrooms.
Hydrolyzed proteins, or protein hydrolysates, are acid- treated or enzymatically treated proteins from certain foods. They contain salts of free amino acids, such as glutamate, at levels of 5 to 20 percent. Hydrolyzed proteins are used in the same manner as MSG in many foods, such as canned vegetables, soups, and processed meats.
In 1959, FDA classified MSG as a “generally recognized as safe,” or GRAS, substance, along with many other common food ingredients, such as salt, vinegar, and baking powder. This action stemmed from the 1958 Food Additives Amendment to the Federal Food, Drug, and Cosmetic Act, which required premarket approval for new food additives and led FDA to promulgate regulations listing substances, such as MSG, which have a history of safe use or are otherwise GRAS.
Since 1970, FDA has sponsored extensive reviews on the safety of MSG, other glutamates and hydrolyzed proteins, as part of an ongoing review of safety data on GRAS substances used in processed foods.
Other reports gave similar findings. A 1991 report by the European Communities’ (EC) Scientific Committee for Foods reaffirmed MSG’s safety and classified its “acceptable daily intake” as “not specified,” the most favorable designation for a food ingredient. In addition, the EC Committee said, “Infants, including prematures, have been shown to metabolize glutamate as efficiently as adults and therefore do not display any special susceptibility to elevated oral intakes of glutamate.”
A 1992 report from the Council on Scientific Affairs of the American Medical Association stated that glutamate in any form has not been shown to be a “significant health hazard.”
Also, the 1987 Joint Expert Committee on Food Additives of the United Nations Food and Agriculture Organization and the World Health Organization have placed MSG in the safest category of food ingredients.
Also, several books and a TV news show have reported widespread and sometimes life-threatening adverse reactions to MSG, claiming that even small amounts of manufactured glutamates may cause adverse reactions.
1995 FASEB Report
the possible role of dietary glutamates in forming brain lesions and damaging nerve cells in humans
underlying conditions that may predispose a person to adverse effects from MSG
the amount consumed and other factors that may affect a person’s response to MSG
the quality of scientific data and previous safety reviews.
FASEB held a two-day meeting and convened an expert panel that thoroughly reviewed all the available scientific literature on this issue.
FASEB completed the final report, over 350 pages long, and delivered it to FDA on July 31, 1995. While not a new study, the report offers a new safety assessment based on the most comprehensive existing evaluation to date of glutamate safety.
An unknown percentage of the population may react to MSG and develop MSG symptom complex, a condition characterized by one or more of the following symptoms:
burning sensation in the back of the neck, forearms and chest
numbness in the back of the neck, radiating to the arms and back
tingling, warmth and weakness in the face, temples, upper back, neck and arms
facial pressure or tightness
bronchospasm (difficulty breathing) in MSG-intolerant people with asthma
Severe, poorly controlled asthma may be a predisposing medical condition for MSG symptom complex.
No evidence exists to suggest that dietary MSG or glutamate contributes to Alzheimer’s disease, Huntington’s chorea, amyotrophic lateral sclerosis, AIDS dementia complex, or any other long-term or chronic diseases.
The level of vitamin B6 in a person’s body plays a role in glutamate metabolism, and the possible impact of marginal B6 intake should be considered in future research.
There is no scientific evidence that the levels of glutamate in hydrolyzed proteins causes adverse effects or that other manufactured glutamate has effects different from glutamate normally found in foods.
Under current FDA regulations, when MSG is added to a food, it must be identified as “monosodium glutamate” in the label’s ingredient list. Each ingredient used to make a food must be declared by its name in this list.
While technically MSG is only one of several forms of free glutamate used in foods, consumers frequently use the term MSG to mean all free glutamate. For this reason, FDA considers foods whose labels say “No MSG” or “No Added MSG” to be misleading if the food contains ingredients that are sources of free glutamates, such as hydrolyzed protein.
In 1993, FDA proposed adding the phrase “(contains glutamate)” to the common or usual names of certain protein hydrolysates that contain substantial amounts of glutamate. For example, if the proposal were adopted, hydrolyzed soy protein would have to be declared on food labels as “hydrolyzed soy protein (contains glutamate).” However, if FDA issues a new proposal, it would probably supersede this 1993 one.
References: Federal Register, Dec. 4, 1992 (FR 57467) and Federal Register, Jan. 6, 1993 (FR 2950); FDA Consumer, December 1993, “Food Allergies: When Eating is Risky.”
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