Monosodium glutamate (MSG) has been largely misunderstood in the past for causing symptoms, such as headache, flushing and tingling, after eating food containing the additive — better known as MSG symptom complex, per the U.S. National Library of Medicine.
Despite reports of these adverse reactions, the Food and Drug Administration (FDA) hasn't been able to find evidence of a direct link between MSG in food and experiencing these specific symptoms. This is why the FDA has deemed MSG to be "generally recognized as safe."
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In rare instances, people who take in 3 grams or more of MSG without food may experience some short-term symptoms, like palpitations, flushing, numbness and headaches, per the FDA. That said, food with added MSG usually contains less than 0.5 grams per serving, so it's basically inconceivable to get 3 grams or more of MSG without food at any given time.
Plus, MSG is naturally found in many foods you may already be eating, and you'll know if the food product you're eating has MSG in it by reading the label.
"The FDA requires food companies to indicate the presence of MSG in the ingredient list as monosodium glutamate," says Razan Hallak, RD, a registered dietitian at the Ohio State University Wexner Medical Center. According to the FDA, MSG can be found in:
- hydrolyzed vegetable protein
- autolyzed yeast
- hydrolyzed yeast
- yeast extract
- soy extracts
- protein isolate
Here's a quick breakdown of some of the other names for MSG.
1. Glutamic Acid
MSG is the sodium salt of the amino acid glutamic acid, which is naturally found in many foods — especially high-protein ones — including tomatoes, mushrooms, tuna fish, anchovies, seaweed, chicken Parmesan cheese and even breast milk, says Michelle Jaelin, RD, a registered dietitian who has done work on de-stigmatizing MSG.
So whether you're eating synthetic MSG that's been added to your food or the kind that naturally occurs in foods, your body doesn't actually know the difference and both are completely safe. Note that although the FDA requires food products containing MSG to list it in the ingredients label, it doesn't require labels on foods that naturally contain it.
Sometimes MSG can be labeled as E621 in products, Jaelin says. The food industry started using this label in the 1960s when rumblings about the "negative effects" of the additive began taking root.
If sodium is what you're concerned about, MSG actually has 12 percent sodium — 2/3 less than table salt, Jaelin says.
2. Yeast Extract
Natural MSG can be found in yeast extract and autolyzed yeast extract, so food products containing these ingredients also have MSG. Yeast extract is a flavoring additive made by mixing added sugar with yeast in a warm environment, Hallak says.
Canned soups and broths, sauces, gravies, packaged snacks, frozen meals and meat products are common foods that contain autolyzed yeast extract, according to the Center for Science in the Public Interest.
3. Hydrolyzed Protein
"Hydrolyzed protein, such as sodium caseinate, naturally contains MSG. Sodium caseinate is derived from the main protein in milk, casein," Hallak says.
Adding hydrolyzed protein to foods increases the protein content, or it can be used as an additive to improve the texture, flavor or quality of the food.
That means if you see products with whey protein isolate, soy protein isolate or hydrolyzed plant protein, they contain MSG.
Do 'Natural Flavors' Contain MSG?
The ingredients in natural flavors aren't known, so it's difficult to say if a food that contains natural flavors would have MSG, Hallak says.
According to the FDA, foods with ingredients that naturally contain MSG can't have labels that claim "no MSG" or "no added MSG" on their packaging. MSG also can't be listed as "spices and flavoring" on labels.