MSG (monosodium glutamate) is a flavor enhancer that has been used in Japanese and Chinese cooking since about 1908. Dr Kikunae Ikeda recognized that seaweed broth had been used as a flavor enhancer and set about to isolate the substance that caused this brothy flavor that he called umami. He published this work in the Journal of the Chemical Society of Tokyo in 1909 and it was translated and republished in English in 2002 in the journal Chemical Senses. The paper is a fascinating little piece of detective work in which he eventually concluded that the umami flavor was caused by glutamate, the sodium salt of glutamic acid. He later developed and patented a process for extracting MSG from seaweed. Today, MSG is produced by fermenting starch, sugar cane, sugar beets and molasses. It is also an integral part of soy sauce(1090 mg.ml), also made from fermented vegetable protein.

Once isolated, MSG became a popular additive in Japanese and Chinese cooking and more recently has come under scrutiny as being the cause of all sorts of disorders from “Chinese restaurant syndrome” to brain lesions and various behavioral and physical disabilities. People have called it an “evil chemical” that is added to poison us and our children and other similar epithets. Always ready to spout nonsense, the redoubtable Joseph Mercola has called it a “silent killer lurking in your kitchen cabinets.”

Around 1968, reports of Chinese Restaurant Syndrome (CRS) began to appear, where a cluster of symptoms were described including flushing, headache and dry mouth. However numerous double blind studies have failed to confirm any relation between MSG and these symptoms.  In one such study volunteers were given either MSG or a placebo. Symptoms attributed to CRS did not appear more frequently in the MSG group than in the placebo group, and most subjects had no responses at all.

Another recent review article noted that while there have been reports of an MSG sensitive subset of the population, this has not been confirmed in placebo-controlled trials.

It is very important to note that this is not an evil chemical additive, but a naturally occurring substance, easily extracted from plants. Just as important, MSG can be found in large quantities in foods such as the bleu cheese in the picture (1280 mg/ml), obtained from Stop and Shop. You will also find it naturally in Parmesan cheese(1200 mg/ml), the British Marmite spread (1960 mg/ml), soy sauce, and in broccoli, peas and tomatoes.

It is also worth noting that the Japanese consume the largest amounts of MSG and they are considered one of the healthiest populations in the world.

Some have tried to argue that MSG as an additive is somehow different than that found naturally in foods. However, since MSG is a single compound and easily purified, it is clear that its source does not matter. This argument is rather like suggesting that the pure MSG from the red bottle is worse than the pure MSG in the green bottle.

In 2005, the journal Nature published a consensus following a meeting on the current state of MSG research, concluding that “the general use of glutamate salts (monosodium-l-glutamate and others) as food additive can, thus, be regarded as harmless for the whole population. Even in unphysiologically high doses GLU will not trespass into fetal circulation.”

In conclusion, the scientific consensus after years of study is that MSG is harmless and that no cluster of allergic symptoms has been observed. MSG is extracted from fermented plant products and occurs naturally in a wide variety of foods: it is not a synthetic additive.

Nonetheless, there are a variety of hoax sites that call into question the safety of MSG, such as truthinlabeling.org, msgtruth.org and probably any of a number of others. They can and should be ignored.

The safety of MSG is firmly established and need not trouble us further.

Related articles

1. Science is so inconvenient to food scares – Sandy Swarc, JunkfoodScience
2. New Seasonings – K. Ikeda
3. Reconsidering the effects of monosodium glutamate – M Freeman, J Am Acad Nurse Proc.
4. Monosodium L-glutamate: a double blind study and review – L Tarasoff and MF Kelley, Food Chem Toxicol
5. What’s the story on MSG? – Marion Nestle Foodpolitics
6. Consensus meeting – monosodium glutamate: an update – P Stehle, Nature
7. If MSG is bad for you why doesn’t everyone in Asia have a headache? Alex Renton, The Guardian

• Chemistry
• Food science