FDA Backgrounder Printed October 1991 Monosodium Glutamate (MSG) Monosodium Glutamate has been used for many years as a flavor enhancer for a variety of foods prepared at home, in restaurants, and by food processors. The substance has become controversial because some people believe they suffer allergic-type reactions when they consume MSG. Because of MSG's common use in Chinese cuisine, these reactions have become known popularly as "Chinese restaurant syndrome." FDA has studied adverse reaction reports and other data concerning MSG's safety for many years. The agency believes that some sensitive people can have mild and transitory reactions in some circumstances when they consume significant amounts of MSG (such as would be found in heavily flavor-enhanced foods). Nevertheless, the agency believes that MSG is a safe food ingredient for the general population. FDA continues to evaluate the regulatory status of MSG and plans to broaden the labeling requirement for the substance to include not only that it be listed that it is added as a separate ingredient (as is currently required), but also that it be listed when it is a functional component of other ingredients. What Is MSG? Asians have used MSG as a flavor enhancer for at least 2,000 years in the form of a broth made with the types of seaweed known as sea tangle. Today, MSG is manufactured by a fermentation process using starch, sugar beets, sugar cane, or molasses. MSG is the sodium salt of glutamic acid, an amino acid found naturally in our bodies. Other salts of glutamic acid, such as calcium glutamate and potassium glutamate, also have flavor-enhancing properties. Glutamic acid, or glutamate, is a major "building block" of many proteins in foods, such as cheese, meat, peas, mushrooms, and milk. Some glutamate is present in foods in a "free" form, not bound with other amino acids. It is only in this free form that glutamate can enhance a food's flavor. Part of the flavor-enhancing effect of tomatoes, certain cheese, and fermented or hydrolyzed protein products is due to the presence of free glutamate. Hydrolyzed proteins, or protein hydrolysates, are acid-treated or enzymatically-treated proteins from certain food sources. They contain salts of free amino acids, including glutamates, at levels of 5 to 20 percent. Hydrolyzed proteins are used in place of MSG as flavors and flavor enhancers in many foods, such as canned vegetables, canned tuna, and processed meats. MSG, as sold in grocery stores, is a fine, white crystal substance, similar in appearance to salt or sugar. It does not have a distinct taste of its own. Precisely how MSG works to "wake up" or enhance the flavor of foods in not fully understood. Many Western scientists believe that MSG stimulates taste receptors in the tongue, while their Eastern counterparts believe the chemical has a unique fifth basic taste -- beyond salty, sweet, sour, and bitter -- that they call "umami," derived from the Japanese word meaning "deliciousness." Scientific Reviews of MSG FDA is evaluating MSG's safety as part of an ongoing project initiated in 1970 to review safety data on the ingredients of processed foods that are listed as "generally recognized as safe" (GRAS) under the 1958 Food Additives Amendment to the Federal Food, Drug, and Cosmetic Act. Until its evaluation is complete, MSG remains on the GRAS list with a requirement that it must be identified as "monosodium glutamate" on the ingredient label of any food to which it is added. In 1980, as part of the GRAS review, an independent body of scientists, the Select Committee on GRAS Substances of the Federation of American Societies for Experimental Biology, concluded that MSG is safe at current use levels, but safety at significantly increased levels of consumption requires additional evaluation. FDA's Advisory Committee on Hypersensitivity to Food Constituents also reviewed MSG and in 1986 concluded that MSG posed no threat to the general public, but that reactions might occur in a small percentage of the population. This position was later reinforced by a report for the FDA Center for Food Safety and Applied Nutrition's Adverse Reaction Monitoring System (ARMS). The ARMS report, released in 1990, found that a small percentage of individuals have moderate reactions such a skin flushing, tightening of jaw and upper chest muscles, and headaches shortly after eating food containing MSG. No severe reactions were documented, but one investigator reported aggravation of asthma in some individuals after they had consumed MSG, in some cases many hours later. Because of the way the testing was conducted, it couldn't be determined whether MSG actually caused these asthmatic reactions. One of the problems with the reports of adverse reactions that FDA has received is that it is difficult to link the reactions specifically to MSG. Most are cases in which people have had reactions after eating certain foods containing MSG and are not controlled studies. A controlled study was conducted in 1972 by Richard A. Kenney, Ph.D., of George Washington University Medical Center, Washington, D.C. Dr. Kenney's study used placebos and orally administered MSG in a representative sample of humans. The study showed that one-third of those tested experienced symptoms when given large doses of MSG but, at amounts normally consumed with food, almost none did. In fact, some people who claimed to be sensitive to MSG reacted similarly when exposed to the placebo. Scientists' concerns are not related to consumption of foods that naturally contain glutamates; the concern, rather, is that a diet extremely high in MSG used as a flavor enhance could result in acute elevation of glutamate in the blood. Hypothetically, this could cause overstimulation of portions of the brain, adversely affecting the central nervous system and possible leading to brain injury. However, no scientific evidence has surfaced to support the hypothesis that MSG, consumed at levels found in food products, can cause brain injury. Unconfirmed cases of such injuries continue to be examined, however, as do reports by George Schwartz, M.D., a Sante Fe, N.M., physician. Dr. Schwartz alleges that even at low doses, glutamates can cause life-threatening reactions. He has published a book titled In Bad Taste: the MSG Syndrome, and has made many public statements about this belief in the danger of MSG. A group also known as "No MSG" also supports Dr. Schwartz's views. Although reports such as Dr. Schwartz's may be of value in identifying a population for future investigation, without additional information they cannot lead to meaningful conclusions concerning MSG's potential role in provoking these reactions. The most recent evaluation of MSG's safety came from the European Communities' Scientific Committee for Food. In a report released by the committee in June 1991, MSG was reaffirmed as safe, and its "acceptable daily intake" was established as "not specified," the most favorable designation for a food ingredient. In addition, the EC committee's report 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." The Joint Expert Committee on Food Additives of the United Nations Food and Agricultural Organization and the World Health Organization have also placed MSG in the safest category of food additives. As part of its GRAS review, FDA is contracting with a third party to update a literature review of MSG's safety. When its own review is completed, FDA will publish a proposal in the Federal Register announcing its conclusions on the safety of MSG and will request written comments from the public before issuing a final decision. Label Listing There have been instances when MSG or some other form of glutamate has been added to foods as a component of a hydrolyzed protein without the requirement that it be specifically identified on the label. That has been a controversial issue, and FDA plans to change that provision of the regulations and require glutamate to be specifically listed in those cases as well. Currently, when hydrolyzed protein is an ingredient in a food, FDA's labeling regulations don't require that the glutamate component of the protein be listed separately on the label. (FDA does not usually required components of ingredients to be listed on the label unless there is a public health reason for doing so). However, FDA has reconsidered this position and is now planning to require that the phrase "(contains glutamate)" be added to the label as part of the common or usual name for those hydrolyzed protein products that contain significant amounts of glutamate. For example, the label would sate "hydrolyzed soy protein (contains glutamate)." FDA's decision to make this change does not result from any public health concern about the safety of MSG. FDA is requiring the declaration of MSG because: MSG comprises a significant proportion (up to 20 percent) of hydrolyzed protein. At such levels, the MSG itself (and not just the hydrolyzed protein) functions as a flavor enhancer. Consumer interest in this issue has been high. The "(contains glutamate)" declaration will be published as a tentative provision in a final rule on hydrolyzed protein labeling scheduled for publication in the Federal Register in mid-1992. The tentative final regulation will allow time for additional comments. Reprinted from the International Food Information Council Foundation, 1991

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