Umami booster with an image problem: Who is afraid of glutamate?

It is found in many foods and stimulates taste receptors and minds. But what actually is glutamate? And what’s wrong with his bad reputation?

Yummy in your tummy, but not recommended in large quantities Photo: Panthermedia/imago

“Rocket powder” or “Maria hilf’”: This is what chefs also call glutamate. If the soup doesn’t taste like anything, Maria will provide a miracle solution. And if things have to happen quickly, guests can fly into the flavor universe with the help of rocket powder.

Glutamate excites the umami taste receptors on the tongue. It gives the savory flavor to foods in which it occurs naturally, such as mushrooms, Parmesan cheese and tomatoes. But glutamate also excites people because it can be produced synthetically and is then used as an additive in Asian cuisine and in the Western world in processed foods such as frozen foods, spice mixes or canned soups.

This synthetic glutamate comes from the laboratory and is a white powder. That sounds like chemistry. And every now and then you even see “We don’t use glutamate” stickers on the windows of Asian restaurants. Although the chemical building blocks are based on natural ones, the glutamate added as a flavor enhancer has a dubious reputation. Why is that? And how unhealthy is the additive really?

An acid found in all living things

Chemically speaking, glutamates are the salts of glutamic acid, which is a non-essential amino acid found in all living things. When people, animals or plants produce glutamic acid themselves, it is called endogenous glutamate. It is supplied to an organism from outside, from exogenous glutamate.

The story of exogenous glutamate initially begins harmlessly: In 1907, while having dinner with his family, the Japanese Kikunae Ikeda noticed that the soup tasted heartier than usual, and he suspected that the seaweed kombu, which is widespread in Japanese cuisine, was responsible for this. So the chemist takes them to his laboratory table and breaks them down into their molecular components. He discovered glutamate, which he soon chemically stabilized as monosodium glutamate, or MSG for short.

In 1909, the chemist Ikeda and the entrepreneur Saburosuke Suzuki began the industrial production of MSG. They first treat plant proteins using an extraction process with hydrochloric acid, but the yield of this method is limited. MSG only conquered the world market in the 1950s; it is now produced using a more effective fermentation technology.

A small digression: Glutamate occurs in foods either bound to proteins or free; only the free glutamate provides the intense taste. Through fermentation and maturation, the proportion of free glutamate increases. This is one of the reasons why Gouda aged for 18 months tastes stronger than young Gouda.

A disastrous visit to a restaurant

Then, in 1968, doctor Robert Ho Man Kwok visits a Chinese restaurant in the United States and complains of feeling unwell afterwards. He feels palpitations and numbness in his back and neck and feels weak, as he describes the symptoms in a letter to the editor in the medical journal The New England Journal of Medicine.

Readers of the article remember similar experiences New York Times takes up the topic, and the first scientific studies are initiated in the USA. People who had consumed glutamate are asked about their symptoms, and experimental mice are injected with extremely high doses. The animals then suffer brain damage.

The methods of the early clinical studies were later scientifically criticized, for example because the doses injected were far higher than daily consumption. Additionally, the studies were not properly blinded – meaning doctors and patients knew who was getting real treatment and who was just in the control group, which can influence the results.

An enemy image of the Cold War

In fact, it is still not clear whether the doctor Robert Ho Man Kwok really existed. It is also unclear to what extent political tensions have led to prejudices against Chinese cuisine and thus against glutamate: in the atmosphere of the Cold War, communist China was also an enemy in the United States. The term “Chinese restaurant syndrome” made the rounds back then and to this day leads to “No glutamate” stickers on the windows of Asian restaurants.

The same applies to glutamate as to sugar and salt: the dose makes the poison. In 2023, the Federal Institute for Risk Assessment (BfR) published an assessment on the use of glutamates as food additives, i.e. the E numbers 620 to 625. The BfR is based on the European Food Safety Authority (EFSA), which sets the safe daily intake level for such exogenous substances Glutamate determines.

This has been 30 milligrams per kilogram of body weight per day since 2017. To exceed this amount, a person weighing 60 kilos would have to consume more than 1.8 grams of glutamate as a flavor enhancer every day. That would be almost five times the average consumption in Central Europe.

In sensitive people, symptoms of the so-called MSG symptom complex occur at just over 40 milligrams per kilogram of body weight per day: a burning feeling in the neck, chest pain, nausea, palpitations and weakness. Very high daily intake levels correlate with headaches, insulin increases and increased blood pressure. The EFSA also emphasizes that further studies are necessary in order to be able to better assess intake levels that are too high for infants.

A frowned upon kitchen aid

Glutamate is frowned upon among trained chefs, but for different reasons: “There are many chefs who think glutamate is crap because you can achieve the same thing through cooking,” says Konrad Lenck, deputy head chef at the taz canteen in Berlin. If you’re in the industry, you can create the umami flavor with oyster mushrooms, tomatoes or homemade broth.

“But in the end, the time factor is decisive in many businesses,” says Lenck, and many snack bars don’t have the time to cook down their sauces until they taste creamier and more intense. If in doubt, quickly add stock powder to the sauce, with the same result. During his training, he himself learned in a two-star restaurant where glutamate was used in some dishes, says Lenck.

The chef is familiar with the discussions surrounding the Chinese restaurant syndrome. He believes many Asian restaurants have “No Glutamate” stickers on the door for fear of prejudice. However, he can tell from the first bite whether a dish has actually been cooked with glutamate. “You have a flow of saliva in your mouth that isn’t there otherwise.” If you want to test this yourself, you should simply try your food with a ready-made sauce containing glutamate before seasoning it – and then afterwards. Bon appetit!