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The Truth About 7 Common Food Additives

4. Monosodium glutamate (MSG)

MSG by itself looks like salt or sugar crystals. It is a form of the naturally occurring chemical glutamate. Glutamate doesn't have a flavor of its own, but it enhances other flavors and imparts a savory taste. Tomatoes, soybeans, and seaweed are examples of foods that have a lot of glutamate naturally. Some scientists say that glutamate, also known as "umami," is the fifth essential flavor that the human palate can detect, in addition to sweet, salty, bitter, and sour.

Foods that have it

MSG is an additive used in many foods.

Why it's controversial

Many people claim to have bad reactions when they eat food seasoned with MSG. In the late 1960s, people started talking about "Chinese restaurant syndrome," alleging that food prepared with MSG at Chinese restaurants made them sick.

What the research shows

Many studies over the past four decades have tested the idea that some people may be sensitive to MSG. Most scientists today agree that if there is such a thing as a sensitivity or allergy to MSG, it's extremely rare. Studies haven't found any regular pattern of symptoms that could be typical of a reaction to MSG. Also, people are more likely to have symptoms if they're given MSG crystals than if they eat the same amount of MSG mixed with food.

"It's very hard for me to believe that there's a problem with it," Nestle says. Nevertheless, some still swear that they have bad reactions to MSG. "People who think they have problems with it should avoid it," she says.

How you find it on the label

Some food labels come right out and say that a product contains added MSG. But there are other ingredients that may contain MSG such as "hydrolyzed soy protein" and "autolyzed yeast."

5. Sodium benzoate

What it is

Sodium benzoate is a food additive used as a preservative.

Foods that have it

Sodium benzoate is used in a variety of processed food products and drinks.

Why it's controversial

It's suspected that sodium benzoate, in addition to artificial food color, may increase hyperactivity in some children. Sodium benzoate in soft drinks may also react with added vitamin C to make benzene, a cancer-causing substance.

What the research shows

The 2007 Lancet study that linked additives with increased hyperactivity included the preservative sodium benzoate.

In 2006 and 2007, the FDA tested a sample of almost 200 beverages from stores in different states that contained sodium benzoate and vitamin C. Four of the beverages had benzene levels that were above federal safety standards. The drinks were then reformulated by manufacturers and later deemed safe by the FDA. The agency points out, however, that the tests were limited and that it's still not known how much benzene consumers could be exposed to from beverages.

How you find it on the label

Sodium benzoate is listed among the ingredients on a product label.