Monosodium Glutamate (MSG)

What is E621?

E621 is monosodium glutamate (MSG), the sodium salt of glutamic acid. Glutamate is one of the most common amino acids in food and the main source of umami, the savory taste. It occurs naturally in tomatoes, parmesan, mushrooms, soy sauce and seaweed; commercial MSG is made by fermenting starch or sugar.

Your body handles glutamate from MSG the same way as glutamate from tomatoes or cheese.

Is MSG safe?

Food safety authorities consider it safe at normal intakes. The US FDA classifies MSG as generally recognized as safe. In 2017 the European Food Safety Authority set a group acceptable daily intake of 30mg per kg of body weight per day for glutamates added to food. It noted that typical intakes from all foods can exceed this, which is one reason for moderation.

The idea of 'Chinese restaurant syndrome' (headache, flushing and sweating after eating MSG) has not held up well in double-blind trials. A small number of people report mild, short-lived symptoms after large doses, typically 3g or more taken without food, which is far more than a normal meal contains.

MSG and sodium

MSG contains about 12% sodium by weight, compared with about 39% for table salt. Because it boosts savory flavor, using a little MSG in place of some salt can lower a dish's total sodium. Some studies suggest a reduction of roughly a quarter to a third without making food taste blander.

The bigger issue is where MSG shows up. It is common in chips, instant noodles, seasoning mixes, canned soups and fast food, foods that are often high in salt and heavily processed. Seeing E621 on a label is a useful hint to check the sodium line.

Bottom line

MSG itself is not harmful for most people. Pay attention to the foods it comes in rather than the additive alone. If you believe you react to it, avoiding it is easy: check labels for E621, monosodium glutamate or 'flavor enhancer 621'.