Monosodium Glutamate

Studies have shown that the body uses glutamate, an amino acid, as a nerve impulse transmitter in the brain and that there are glutamate-responsive tissues in other parts of the body as well. Abnormal function of glutamate receptors has been linked with certain neurological diseases, such as Alzheimer's disease and Huntington's chorea. Injections of glutamate in laboratory animals have resulted in damage to nerve cells in the brain, but consuming glutamate in food does not have this effect. Although people normally consume dietary glutamate in large amounts, and the body can make and metabolize glutamate efficiently, the results of animal studies conducted in the 1980's 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 FDA's belief that MSG and related substances are safe food ingredients for most people when eaten at customary levels.

FASEB Report

• the possible role of MSG in eliciting MSG symptom complex;
• 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; and
• the quality of scientific data and previous safety reviews.

FASEB held a 2-day meeting and convened an expert panel that thoroughly reviewed all the available scientific literature on these issues.

Although the information in FASEB's final report of July 31, 1995, is not new, the report offers a new safety assessment based on a comprehensive evaluation of existing data relating to glutamate's safety. The following are some of the report's key findings:

• 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
  • chest pain
  • headache
  • nausea
  • rapid heartbeat
  • bronchospasm in MSG-intolerant people with asthma
  • drowsiness
  • weakness
• In otherwise healthy MSG-intolerant people, the MSG symptom complex tends to occur within 1 hour after eating 3 g or more of MSG on an empty stomach or without other food. A typical serving of glutamate-treated food contains less than 0.5 g of MSG. A reaction is most likely if the MSG is eaten in a large quantity or in a liquid, such as a clear soup.

• 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.

• There is no scientific evidence that the levels of glutamate in hydrolyzed proteins cause 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 must be specified by name in this list.

• In 1994, FDA received a citizen's petition requesting changes in labeling requirements for foods that contain MSG or related substances. The petition asks for mandatory listing of MSG as an ingredient on labels of manufactured and processed foods that contain manufactured free glutamic acid. It further asks that the amount of free glutamic acid or MSG in such products be stated on the label, along with a warning that MSG may be harmful to certain groups of people. FDA is evaluating the petition.

  Copies of the 1995 FASEB report are available for $50 each by writing to FASEB, 9650 Rockville Pike, Bethesda, MD 20814.