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The Fifth Flavor
For: Food Additives: What You Need to Know, June 2002

One thing that stumps the Chinese is Americans' fear and loathing of monosodium glutamate, or MSG, according to a recent article in the New York Times. Known in China as the "king of seasonings," MSG is an ingredient there in almost all foods, at home and in restaurants. It's just as popular in Japan, too. Indeed, consumption is rising, without any adverse reactions being reported, according to the Times. For years MSG has been on the World Health Organization's list of "safest foods," along with vinegar and salt. No one knows how much the Chinese actually eat, but average consumption in Japan is about one pound a year per person. In Taiwan the average consumption is 2.4 pounds a year—about 3 grams (one-tenth of an ounce) a day.

A Wellness Letter subscriber living in China tells us that MSG is usually translated as "gourmet powder," but reports that visitors from the U.S. often express their aversion to it. He asks if their aversion is well founded. No, not if you go by the evidence.

Pizza and pea syndrome?

MSG is not the product of some laboratory, but is the naturally occurring salt of glutamic acid, also called glutamate, an amino acid (a building block of protein). MSG is about 12% sodium and 78% glutamic acid. Glutamic acid is present in human cells and in many foods, where it may be bound to other amino acids or may be free. It's the free form of glutamate that imparts a unique flavor—a savory quality different from sweet, sour, salty, and bitter (the standard four flavors). The Japanese call this umami and consider it a fifth flavor. MSG has been in use for centuries, extracted from seaweed or fermented from molasses or sugar beets. Certain foods contain a lot of free glutamate naturally, which is one reason they taste so good. These include such favorites as tomatoes and Parmesan cheese. Green peas and corn are also rich in free glutamate. A pizza with tomato sauce probably has more MSG than a plate of mu shu pork.

Scientists have long debated whether MSG causes any harmful reactions. It's been accused of triggering everything from headaches and asthma to heart irregularities and facial burning. Still, many large studies have failed to find any relationship between MSG and adverse symptoms. In a 1998 study, very large doses of MSG without food caused symptoms such as lightheadedness in some people who claimed they were sensitive, but there were no serious or lasting effects, and retesting did not produce the same results. And the same dose in food produced no adverse effects. Clinical studies have not found that food containing MSG provokes asthma symptoms. For instance, as we reported last year, a study conducted at the Scripps Research Institute in La Jolla, California, showed that a large dose of MSG was no likelier to cause a reaction in asthmatics than a placebo.

Asian cuisine exonerated

The World Health Organization, the FDA, and the Scientific Committee for Food of the European Commission have all concluded that human studies have failed to confirm the existence of "Chinese restaurant syndrome." They haven't ruled out the possibility, though, that a few people might be sensitive to MSG if they swallow a huge amount of it without food. But that would be like swallowing a huge dose of sodium chloride (salt) without food.

Last words: If you don't want MSG in your food, there's no reason to eat it. But there is no reason to avoid it.

UC Berkeley Wellness Letter, April 2001