Recently, an acquaintance of mine experienced a strange and disturbing reaction while driving home to Whistler from a luncheon date in Vancouver. It began with a sudden headache and quickly progressed to drowsiness so overpowering that he opened the windows and drove in the freezing cold to stay awake.
“The strange part of this,” he said, “was that I wasn’t the least bit tired. Just sleepy, almost as if I’d been drugged. And then, after a couple of hours it went away.”
What my friend had experienced was almost certainly an allergic reaction to monosodium glutamate, or MSG, as it is commonly known. He had eaten at a Chinese restaurant, where the flavour enhancer is an ingredient in most, if not all dishes.
MSG, which is sold under trade names such as Accent, Ajinomoto and Vetsin, is in fact pervasive now in processed foods, including fast foods, canned, frozen and dried foods, seasonings, salad dressings, soya and other sauces, chips, and stock cubes such as bouillon and chicken.
MSG was isolated in Japan way back in 1907 and then mass-produced (by fermenting starch, sugar beets, sugar cane or molasses) as a substitute for seaweeds that the Japanese had used for centuries to season food. It is a form of glutamic acid, which makes up 10-25% of all food protein. When these proteins are broken down in the manufacturing process, something called free glutamate is released, and that becomes the flavour enhancer that is added to foods.
If the chemistry is complex – and it is to the lay-person – then so are the health issues. After scores of studies, there is still no clear answer as to whether MSG is harmful to humans or not. There are, however, at least two clear conclusions: too much MSG is probably not good for anyone, and even small quantities elicit a variety of negative reactions in people who are sensitive to it.
The US Food and Drug Administration gives MSG its GRAS (“generally recognized as safe”) rating, and other countries, including Canada, agree. But a number of studies, not least a comprehensive literature review commissioned by the FDA, has recognized so many adverse reactions that there is now a list of these, known as MSG complex syndrome.
The list includes: headache, burning sensation or numbness in the back, neck and arms, facial pressure or tightness, chest pain, nausea, rapid heartbeat, drowsiness and muscular weakness. People who suffer migraine headaches or severe, poorly controlled asthma seem to be particularly subject to reactions.
There are other possible side effects. A study in rural China published last year found a link between MSG and obesity, though one wonders whether the flavour enhancer was directly to blame or if people simply ate more because food tasted better.
There is also the issue of whether MSG causes nerve damage. Since the 1970s, a scientific debate has been raging about the significance of tests that linked high levels of glutamic acid to brain damage in mice. A reaction of this kind in humans could trigger neurological diseases such as Alzheimer’s.
Although Health Canada takes the position that MSG is safe, foods containing MSG must be labeled as such in this country. This is at least tacit acknowledgement that some people react badly to it.
If you suspect you are one of those people, avoid fast food chains and junk food, and if you are eating out, ask that your food be MSG-free.
©Dr. Gordon, 2009.