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What Is MSG—and How Bad Is It, Really?

Do you get headaches or feel tingly after eating Chinese food? It may be from the flavor enhancer monosodium glutamate—how bad is MSG, really?

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What is MSG?

It's a flavor enhancer. Monosodium glutamate (MSG) is commonly added to Chinese food, canned vegetables, soups, and processed meat. "MSG contains glutamic acid (non-essential amino acid) which is also naturally found in tomatoes, grapes, cheese, mushrooms and other foods," says Emily Rubin, RD, LDN, the head dietitian for the celiac and fatty liver centers at Thomas Jefferson University in Philadelphia. (MSG is actually the reason that Kentucky Fried Chicken is finger-lickin' good.)

detail of the lids of four cans of conserved foodCarlos Caetano/Shutterstock

Why is MSG added to food?

It's added for its "umami quality." MSG is not salty, sweet, sour or bitter, but it still provides a savory flavor. Umami is actually considered a fifth flavor category.

 Udon with Padthai sauce, Healthy Vegetarian/vegan menu; Padthai noodle with smoke tofu and mixed vegetable - chinese baby Bok Choy , garlic chive, shallot and crushed peanut topping. chopstick hold.homelesscuisine/Shutterstock

MSG: The backstory

The whole brouhaha about MSG and health started in 1968 when a biomedical researcher wrote to the editors of the New England Journal of Medicine citing a strange illness he developed after eating at Chinese restaurants—specifically those that cooked with MSG. His symptoms included numbness, weakness, and heart palpitations and became known as "Chinese Food syndrome." The letter went viral—even though this was a time before social media. Soon after its publication, everyone turned on MSG and a flurry of research on its health effects began.

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The FDA weighs in on MSG

The U.S. Food and Drug Administration says that MSG is "generally recognized as safe" (GRAS). The watchdog group requires that foods containing added MSG list it on the ingredient panel as monosodium glutamate. If MSG is found naturally in some of the ingredients (hydrolyzed vegetable protein, autolyzed yeast, hydrolyzed yeast, yeast extract, soy extracts, and protein isolate), the manufacturer does not have to list MSG on the label. That said, these foods can't say "No MSG" or "No added MSG" on their packaging. MSG also cannot be listed as generic spices and flavoring. Use this cheat sheet on how to decode tricky language on food labels.

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And across the pond...

In 2017 the European Food and Safety Authority (EFSA) stated that an Acceptable Daily Intake (ADI) of MSG is less than 30 mg/kg body weight. "This means for a 154-pound person, any intake of fewer than 2,100 mg per day would be safe," says Barry Sears, PhD, author of the Zone Diet book series."The average intake in the United States of MSG is about 550 mg per day." Rubin agrees: "MSG is rarely added in large quantities to any food, and MSG is safe in low to moderate amounts."

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The case against MSG: Leaky gut

Not everyone is convinced that MSG is benign: "It's probably one of the most harmful substances that one can eat," says Michael Galitzer, MD, an integrative medicine specialist in Los Angeles, Calif. and author of Outstanding Health: A Longevity Guide for Staying Young, Healthy, and Sexy for the Rest of Your Life. "Its ingestion can cause inflammation of the small intestine, referred to as leaky gut, which will result in symptoms such as bloating, gas, diarrhea, and abdominal pain," he says. These 7 signs suggest you may have a leaky gut.

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The case against MSG: Headaches

MSG has been linked to headaches—including a debilitating migraine headache—but this link is far from conclusive. In fact, some research suggests MSG does not increase the risk of migraines. These findings were presented by the headache information site Curelator at the 2018 Annual Scientific Meeting of the American Headache Society. In January 2018, the International Headache Society struck MSG from a list of causative factors for headaches. Here are 13 foods that do make headaches worse.

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The case against MSG: Chinese restaurant syndrome?

There has been a controversy whether some people develop symptoms such as headaches, muscle aches, and tingling after consumption of MSG, Rubin says. "There has been no definitive evidence of a link between MSG and these symptoms." Despite this, some 50 years after the syndrome was first named, U.S. consumers still say they avoid MSG, according to the International Food Information Council, an industry-funded group.

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The case for MSG: Healthier eating habits?

Consuming umami-rich broth may promote healthy eating behaviors and food choices, especially in women at risk of obesity, according to a study in Neuropsychopharmacology. Researchers evaluated changes in the brains of women after they consumed chicken broth with or without MSG. The broth with added MSG lit up areas of the brain connected to satisfaction and better control over eating, the researchers discovered. What's more, women who had the broth made better choices during their meal, favoring foods with less saturated fat. "Our study suggests the possibility that people at high risk of obesity could benefit from an umami-rich broth before a meal to facilitate healthy eating and healthy food choice," says Miguel Alonso-Alonso, MD, PhD, an Assistant Professor at the Center for the Study of Nutrition Medicine in Beth Israel Deaconess Medical Center in a news release. "In Western and European cuisine, flavor is built by adding fat (butter, heavy cream, cheese etc)," says Carlene Thomas RDN, LD, a dietitian in the Washington DC- area and author of The Wedding Wellness Workbook: Your Nutrition How-To Before "I Do." "For those struggling with calorie consumption, using umami to season rather than fat could help with healthy weight management." Here are 9 signs your overeating is actually an addiction.

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The case for MSG: Reduced salt consumption?

Adding MSG means less salt, says Dr. Sears. "MSG is also used to reduce the salt content of processed foods [and] the reduction of added salt… could lead to a small reduction in blood pressure." Many packaged foods are high in sodium, but MSG can be a major tool in helping with sodium reduction, Thomas says. "The use of umami allows for less salt, specifically for MSG. That means, sodium levels can be reduced while maintaining or improving the taste of a product." That can make a big difference in sodium intake, she says. Check out these 7 signs you are eating too much salt.

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Are you at risk?

Some people may have a sensitivity to MSG in the same way others have food intolerances to things like lactose, gluten, and wheat, Rubin says. There is no clinical test for MSG sensitivity. "The only way to prevent a reaction is to avoid foods containing MSG," she says. It could lead you to eat a healthier diet: "MSG is generally found in processed foods. If your diet is filled with fresh, whole foods, your MSG intake is low." Next, find out the signs you're eating too many preservatives.