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MSG: Can’t Live with It, Can’t Live without It?

When it comes to the food additive MSG, it’s a matter of taste—and of health, certain people warn. Like many additives, MSG is prized by some people and criticized by others. Either way, it’s a good taking-off point for a field trip to the world of chemistry and taste.

“All Natural Ingredients”
MSG stands for monosodium glutamate. A breakdown of this lengthy name reveals some familiar substances. Glutamate (GLOO-tuh-mate) is an amino acid, one of the building blocks of proteins. As “free” glutamate (not bound in other molecules), it’s a component of chemicals needed for metabolism and the transmission of nerve impulses. Glutamate is also found free in almost every food, including human milk. As you might expect, it’s abundant in protein foods, especially meat, poultry, fish, and aged cheese. Significant amounts also occur in mushrooms, corn, tomatoes, wheat, and peas.

Sodium is a mineral that is also essential to human life. Mono indicates that a molecule of MSG contains one sodium atom. It amounts to about one-third the sodium found in table salt.

From Glutamate to MSG
People used glutamate as a seasoning long before they knew what it was. Ancient Romans obtained it in garum, a sauce made of fermented, salted fish. It’s a long-time favorite in Asian cuisine, especially for giving body and an indescribable flavor called umai to broths and other simple “comfort foods.” Traditionally it was added as a dried seaweed called kombu. Fermented wheat and soybeans and powdered fish and shellfish were other sources.

A Japanese biochemist, Kidunae Ikeda, set out to find the substance in these foods that created this distinctive sensation, which he felt did not fit in the recognized tastes of salty, sour, bitter, and sweet. In 1908, he identified the responsible ingredient as glutamate, which he extracted as a solid by evaporating a solution of kombu dissolved in water. He named this sensation umai (yoo-MAH-mee), a Japanese word meaning “deliciousness,” and suggested it was a fifth taste in its own right. (It had been considered a flavor, the quality that results from a food’s taste, smell, texture, moisture content, temperature, and other factors combined.)

Much research done in the last 20 years tends to confirm Dr. Ikeda’s theory. Scientists have found taste buds that are specialized to respond to glutamate, the same way that other buds are especially sensitive to salts and sugars. MSG is produced by a process that updates traditional methods of extracting glutamate. Molasses or other sugars are fermented using carefully bred bacteria, which produce glutamate as a by-product. The sodium is added as a stabilizer and creates a compound in the form of large crystals that are easily stored and readily dissolved in food.

A Taste for Controversy
MSG itself has little flavor. Its value is in bringing out the umami “notes,” or qualities in foods. What is this umami taste? It’s often likened to foods that are high in free glutamate. It might be called “meaty,” as in the texture mushrooms add to a dish. It may be called “savory,” like the salty-sweetness of tomato sauce or Parmesan cheese. MSG seems to intensify all tastes except sweet ones. Only small amounts are needed. Increasing MSG past a certain point doesn’t increase a food’s flavor.

This versatility has made MSG one of the most common additives in the food industry, found in products ranging from sausage to soft drinks. It’s popular for returning flavor that’s lost in low-fat and low-sugar foods. It’s sometimes used in foods designed for older adults, whose tastes buds often lose sensitivity. MSG is also found in “flavor enhancers” sold on supermarket shelves.

In addition, free glutamates are added to many processed foods. On labels, they’re listed as yeast extract, malt extract, whey protein, textured protein, and numerous other names.

As a low-cost additive, MSG is also used to improve the flavor of poor quality food—and that’s just one complaint made against it. Several years ago, some people began reporting a variety of allergic reactions after eating foods containing MSG, notably headache, flushing, stomach upsets, and difficulty breathing. Some researchers claim that MSG triggers asthma attacks and leads to depression, behavior problems in children, and nervous system disorders.

Years of extensive testing by governments, industry groups, and universities have shown no link between the additive and any negative reaction. In fact, in studies using both animals and humans, subjects consumed abnormally large amounts with no effects, internal or external, of any kind. Scientists think that allergic symptoms may be due to known allergy triggers that are often used in recipes with MSG—the peanuts or soy sauce in a stir-fry, for example—which is another good reason to pay attention to your food choices.


Chemically, glutamate is a(n) ____.
A)fatty acid
B)amino acid

Glutamate’s use in foods goes back ____.
A)about 20 years
B)to the early 1900s
C)several centuries
D)none of the above

Free glutamate is most likely highest in ____.
A)crab-stuffed mushrooms with grated cheese
B)carrot-raisin salad with apple cider vinaigrette
C)cherry ice cream with chocolate syrup
D)cooked pumpkin with brown sugar

MSG differs from glutamate in that MSG ____.
A)is a manufactured product
B)contains sodium
C)results from fermentation
D)all of the above

Food makers are most likely to use MSG to ____.
A)dry grapes to make raisins
B)increase the flavor in onion-flavored potato chips
C)add color to fruit punch
D)extend the shelf life of jelly doughnuts

MSG has been suspected of causing ____.
A)allergic reactions and nervous system disorders
B)heart attacks and difficulty sleeping
C)memory loss and emotional problems
D)asthma attacks and diabetes

The latest scientific data suggests that MSG should be ____.
A)banned from the food supply
B)avoided until further studies reach definite conclusions about its safety
C)considered safe but not used unnecessarily
D)added to more foods to improve nutrition

Suppose you hear someone describe MSG as “an unnatural ingredient.” Is this statement accurate? Explain.
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