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The fifth basic taste, umami (Japanese: umai-delicious, mi-taste) is inseparably linked to glutamate receptors. These are the receptors which make eating food with sodium glutamate – a chemical flavour enhancer that is unfairly held in disrepute – so pleasant. Its only fault is the fact that it being added to almost every unhealthy food product makes these delicious and attractive to us.

Glutamic acid can be found in products that are rich in proteins, like meat or milk. It was a very important evolutionary development that made us able to recognize that kind of food. Glutamates are also the reason why we like tomatoes, broccolis, but also crisps, instant soups and much more unhealthy dishes. Glutamic acid derivates, most notably sodium glutamate (MSG), are a mandatory ingredient of theirs spice mixtures. It is no wonder. MSG is the reason for their deep, delicious flavour. The reason for them being sold well.

The taste of seaweed

The flavour enhancer we are talking about, monosodium glutamate, also known as E621 is the salt of glutamic acid, non-essential amino acid that is present in almost every known protein. It was first synthesized by Japanese scientist Kikunae Ikeda. He first isolated the acid from Laminaria japonica, an alga which made for a soup he simply loved, yet was characterised by a flavour impossible to describe with any of four basic tastes (sour, sweet, bitter, salty) known so far. When ionized, glutamic acid forms glutamates, which when added to food give it this characteristic full taste.

Among many kinds of salts, sodium glutamate turned out to be both soluble and easily crystallizing, but above all it was umami, delicious. It was a matter of time before mass production was started and market entry took place – first in Japan, and afterwards worldwide. More than 400 thousands of tones of it are sold every year.  

Bacterial snacks

MSG, which is now produced in biosynthesis, by bacterial fermentation, is not yet popular in Europe as a separate spice (just the opposite is the case in Asian cuisine). That does not change the fact, that we eat lots of it, in almost every kind of snack, fast-food, instant soup, salad dressing, spice mixes (also herbal ones) and much more. The ingredient is classified as safe both by FDA and European Union, with no restrictions to use.

Still, some producers are proudly printing “No MSG” on the packages. There is also a group of producers that disguises MSG under other names, like yeast extract, hydrolyzed protein, caseinate, yeast nutritient, autolyzed yeast, gelatine etc.

Chinese Restaurant Syndrome

Why? After years of adding it to everything (mainly highly processed, unhealthy food), E621 gained poor reputation. Apart of Chinese Restaurant Syndrome it is accused of enhancing coronary artery disease, atherosclerosis, obesity and related diseases, causing irritable bowel syndrome, infertility, ADHD and many others. While some researchers publish studies suggesting that prohibiting glutamate is necessary, others says MSG does no harm (or even helps healing).

The widest review so far was published in The Journal of Nutrition, in 2000. It states that sodium glutamate is completely safe. In his publication Raif et al. studied patients that reported Chinese Restaurant Syndrome, and suffered from asthma, urticaria, atopic dermatitis, ventricular arrhythmia, neuropathy and abdominal discomfort. Quite a lengthy list. The substance was given with or without food to one group of patients. The other group was given a placebo.

Imaginary disease

The data from the study suggests that monosodium glutamate is a generally safe food flavouring agent. With a very rare exception of hypersensitivity, even large doses of MSG should not be a reason for any malaise. However even then, neither persistent nor serious effects were observed, and the frequency of the responses was low. More importantly, the responses reported were inconsistent and not reproducible, and when MGS was given with food – they were not observed at all.

Just like the other symptoms, it is hard to connect obesity with glutamate itself. It is worth noting tough, that it is important ingredient of highly processed products, with high glycemic index. We all know that these are the foods we get fat from. On the other hand we often hear about researches that are made in collaboration with business, and their results are known in advance. At the end of the day, it is our choice. Do you eat or do you avoid?

Extra: There are many other substances added to our food, that are similar to monosodium glutamate, enhancing flavour: mono- and di- potassium, calcium, magnesium and ammonium  glutamates, but also non glutamates: inosinic or guanylic acid and their salts, calcium and disodium ribonucleosides.

Samanta Makurat

Chemistry student at the University of Gdańsk, fascinated with molecular modeling. Nature enthusiast.


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