Monosodium Glutamate

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 glutamate in the form of MSG.

Glutamate is found in virtually all proteins. It is a normal component of the human body both in free form and as a building block in proteins. It also is a natural component of many foods, including parmesan cheese, chicken, and tomatoes. Free glutamate is added to foods to enhance flavor primarily in the form of MSG. The glutamate content of MSG is 78 percent; the remainder is sodium and water.

Injections of glutamate in laboratory animals have resulted in damage to nerve cells in the brain. Consumption of glutamate in food, however, does not cause this condition. While people normally consume dietary glutamate in large amounts and the body can make and metabolize glutamate efficiently, the results of these animal studies conducted in the 1980s raised a significant question: Can MSG and possibly some other glutamates harm the nervous system?

A 1995 report from the Federation of American Societies for Experimental Biology (FASEB), an independent body of scientists, helps put these safety concerns into perspective and reaffirms the Food and Drug Administrations (FDA) belief that MSG and related substances are safe food ingredients for most people when eaten at customary levels.

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 respond with temporary adverse reactions after consuming large doses (3 grams or more) of glutamate without food. Parmesan cheese, a food with one of the highest levels of naturally occurring glutamate, contains about 1.3 grams of free glutamate per 100 grams. To consume three grams of glutamate from this source, one would need to consume 50 tablespoons of grated Parmesan cheese. 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 to 2.5 grams.

The Institute of Food Technologists (IFT) believes that people who are concerned that they may be sensitive to MSG should consult their physicians for challenge tests to determine if MSG is the cause of their adverse reactions.

Although FDA has not fully analyzed the FASEB report, the agency believes that the report provides the basis to require glutamate labeling. FDA will propose that foods containing significant amounts of free glutamate declare glutamate on the label. This would allow consumers to distinguish between foods with insignificant free glutamate levels and those that might contribute to a reaction.

Sources: Monosodium Glutamate A statement of the Institute of Food Technologists. Food Technology, October 1995. FDA Backgrounder on MSG

Karen Penner, Ph.D.
Extension Specialist, Food Science

11/95 File: FOOD SAFETY/General

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