MSG (Monosodium glutamate, E621)

What is MSG?

MSG is glutamic acid — one of the most common amino acids in protein — combined with sodium. Once it dissolves, the glutamate in MSG is the same as the glutamate naturally present in tomatoes, aged cheese, mushrooms and soy sauce. Today it is made by fermenting starch, sugar beets, sugar cane or molasses.

MSG contains about a third as much sodium as table salt by weight, and it is used in much smaller amounts.

Why is MSG used in food?

MSG adds umami, the savory, "meaty" taste. It rounds out soups, broths, snacks, seasoning blends, instant noodles, chips and restaurant dishes, and it can make lower-salt foods taste less flat.

Ingredients such as yeast extract, hydrolyzed vegetable protein and autolyzed yeast also contain free glutamate and are used for the same reason.

Is MSG safe? What the research says

What the FDA says. The FDA classifies MSG as generally recognized as safe (GRAS). An independent review by FASEB in the 1990s found that some sensitive people may have mild, short-lived symptoms — headache, flushing, tingling, palpitations, drowsiness — after eating 3 grams or more of MSG without food. A typical serving of a food with added MSG contains less than 0.5 grams.

Perspective on amounts. According to the FDA, an average adult takes in about 13 grams of glutamate a day from protein in food, compared with about 0.55 grams from added MSG. The body handles glutamate from both sources the same way.

What EFSA says. In 2017 EFSA set a group acceptable daily intake of 30 mg/kg of body weight for glutamic acid and its salts (E620–E625). It noted that people whose diets are heavy in foods with added glutamates — and children with average diets — may exceed that level.

The "MSG symptom complex." Reports of headaches and other symptoms after eating MSG go back to the late 1960s. But in studies where people who describe themselves as MSG-sensitive were given either MSG or a placebo without knowing which, scientists have not been able to trigger reactions consistently, according to the FDA.

Bottom line: at normal amounts MSG is considered safe. If you notice a reaction, it is reasonable to avoid it — and to check for other glutamate-rich ingredients too.

MSG regulation: US vs EU

In the US, MSG added to food must appear in the ingredient list as "monosodium glutamate." Products containing hydrolyzed protein or yeast extract cannot be labeled "No MSG" or "No added MSG," because those ingredients contain free glutamate. In the EU it is permitted as E621 under maximum levels.

Who should limit or avoid MSG?

• People who notice symptoms after MSG-heavy meals. Reactions reported in studies are mild and short-lived, but avoiding what bothers you is reasonable.
• People watching sodium. MSG adds some sodium, although less than the salt it can partly replace.
• MSG is not related to gluten, despite the similar-sounding name, and is fine for people with celiac disease.