What is MSG and how does it work?

Bowl of foodWe all deserve to know what is in our food, which is why all packaged food carries a list of ingredients. Without a sound understanding of chemistry however, some of these ingredients can sound scarier than they truly are. MSG, or monosodium glutamate to give it its full name, is a brilliant example of this.

MSG is widely believed to cause Chinese Restaurant Syndrome – a collection of symptoms including headache, dizziness and chest pain along with many others. First coined in 1968 by Robert Ho Man Kwok, people have reported experiencing these symptoms after eating in restaurants that add MSG to their food ever since.

Acting as a flavour-enhancer, MSG is added to food to improve the taste. The flavour it evokes is called umami (the word means delicious or ‘yummy’ in Japanese) and is best described as a savoury, broth-like meaty taste. It is caused by our tongue sensing the amino acid glutamic acid and is naturally found in a variety of foods: parmesan cheese, soy sauce, mushrooms and chicken to name a few. Remarkably, we have umami taste buds that only sense this umami taste on our tongues (we don’t just have taste buds for detecting salty, sour, sweet and bitter, as you were taught at school).

MSG is a ‘salt’ form of glutamic acid – containing sodium. Our taste buds respond in the same way to MSG as they do to the natural glutamic acid in our food – causing us to taste the umami taste from food seasoned with MSG. It can be thought of as a seasoning, much like salt. So one additional reason why some cooks might use MSG as an alternative to salt is that it only contains a third of the sodium found in table salt and can be used in smaller amounts to flavour food (high sodium diets being a risk factor for stroke and high blood pressure). When MSG is used with a small amount of table salt it can reduce the total sodium in a recipe by 20 to 40 %.

Because of the link to Chinese restaurant syndrome, MSG has been extensively studied to investigate the adverse reactions in humans. However double-blind controlled studies of individuals who believed they were sensitive to MSG, showed that food containing MSG wasn’t really causing their problems. Another study found that allergic type reactions commonly blamed on MSG are more often due to shrimp, peanuts, spices and herbs – not the addition of this flavour enhancer.

If you experience symptoms such as dizziness and feeling flushed after eating, all the science suggests that it is not a reaction to the MSG. It could however be an undiagnosed allergy or a symptom caused by something else. Excellent advice for what to do if you suspect you have an allergy can be found here. In the end MSG turns out not to be the villain some people think it is and may actually help to lower salt levels in our food if used as a substitute for some salt. Interestingly, many top fine-dining restaurants (especially those in Japan) also use MSG. And if you think that sounds scary, then just consider that the alternative name for refined salt is the sinister-sounding ‘sodium chloride’. Now I don’t suppose you’ll find many cooks who will go near a stove without some of that!

Photo Credit: SlinkyDragon via Compfight cc


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Article by Nathan Beal

December 1, 2014

Nathan is currently in the throes of a PhD in Computational Chemistry at the University of Manchester. When he’s not behind a computer, he’s outside enjoying the sights of the city. A fan of The Walking Dead, he has a strange apathy to all things football-related.


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One thought on “What is MSG and how does it work?”

  1. What a stupid article. When I eat MSG I get really sick and pounding headaches. For you to say because of a ‘few double blind studies’ that it isn’t MSG is very ignorant. When you are uninformed on a topic. its better you don’t write anything at all rather than spreading mistruths. MSG is harmful to the body

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