In 1968, Dr. Robert Ho coined the term "Chinese Restaurant Syndrome" after some people who ate Chinese food became unwell. These days, the disorder is more appropriately called "MSG Symptom Complex," and it still affects people who are hypersensitive to the ingredient.
Nature and Distribution of Monosodium Glutamate
Monosodium glutamate is the sodium of glutamate. It is 78% free glutamic acid, 21% sodium, and up to 1% contaminants. It is the most abundant amino acid and is present naturally in meats, fish, shellfish, certain fruits, vegetables, seeds, some dairy products, and seaweed. It is also produced by the body - about 50 g of glutamate per day for fuel, and as precursor of proteins, neurotransmitters, antioxidant hormones, nucleotides, and nucleic acids. MSG was identified by Kikunae Ikeda in 1908 in seaweed. In 1909 it was introduced in the United States, but it wasn't until after World War II that MSG became widely used, when the U.S. Military realized that Japanese rations tasted better than American food provisions because of MSG. It occurs as "glutamine" in the following fruits:
- Apples
- Black Currants
- Dates
- Oranges
- Pineapples
It also occurs in the following foodstuffs as "glutamic acid"
- Vegetables: Asparagus, Cabbage, Bok-Choi, Pak-choi, Mustard, Celery, Chives,Spinach, Cucumber,Peas
- Legumes (pigeon peas, mung bean, chick peas, sprouted seeds)
- Nuts (peanuts, almonds)
- Seeds: pumpkin, and sesame seeds
- Lentils
- Watermelon
Dangers of MSG
In sensitive persons, MSG can act as an "excitotoxin;" meaning it can overstimulate cells to the point of damage or even death. According to the Food and Drug Administration (FDA), MSG Symptom complex includes:
- Numbness, tingling sensation,chest pain, headaches, nausea, fatigue, rapid heart beat, drowsiness, and weakess. It is also associated with:
- Eye damage, disorientation,depression,and neurological problems associated with Parkinson's disease, Alzheimer's disease, Lou Gehrig's disease, etc.
Children and expectant mothers are at risk for MSG because the "blood-brain" barrier (the barrier that keeps toxins out of the brain) is not fully developed in youngsters. MSG can also cross the "placental" barrier and accumulate in the baby's blood. Although glutamine plays a role in the development of the baby's brain, an excess has been shown to cause significant impairment of brain development in infants and can lead to mental retardation later on.
How to Reduce Your Risk of MSG Toxicity
MSG itself has no taste, but it acts on the taste receptors of the tongue giving meats/proteins and vegetables a more "savory" flavor. It does not enhance the taste of fruits, candies, cookies, and cakes. It is widely used in processed foods, sauces, gravies, soups, snack items, salad dressings, condiments, and so on. Health Canada and the FDA recommends the following strategies:
- Read food labels. Ingredients must be declared on the label, allowing sensitive people to avoid MSG.
- It is illegal to label a product with the words: "no MSG added," "contains no MSG" or "no added MSG" because they are misleading, especially if the other sources of glutamate are present such as hydrolyzed protein, hydrolyzed vegetable protein, hydrolyzed plant protein, soya sauce or autolyzed yeast.
- If you must use MSG, use it in moderation - about one teaspoon (5 ml) only. Larger amounts will not further enhance the flavor of the food.
- Avoid commercially prepared foods and foods prepared outside the home. Many of these foods already contain MSG and further addition only increases your risk if you're sensitive to MSG
Note: Health Canada regulates food labelling policies under the Food and Drugs Act and Regulation. The Canadian Food Inspection Agency (CFIA) oversees the administration of food labelling policies and enforcement of labelling requirements.
References:
Blaylock RL "Excitotoxins: The Taste That Kills" Health Press Santa Fe, NM 1997
"FDA and MSG" US Food and Drug Adminstration Publication August 31, 1995
Newsholme P et al. "Glutamine and Glutamate: their role in cell metabolism and function" Cell Biochem and Function 2002;21(1):1-9
"MSG Questions and Answers" Food and Nutrition Health Canada Website Updated June 27, 2008
Mosby, Ian "That Won-Ton Soup Headache: The Chinese Restaurant Syndrome, MSG and the Making of American Food" Social History of Medicine 2009;22(1):133-151
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