Harmful glutamate and heavy water: how are food myths born?

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

There are many myths about nutrition and food preparation. Some of them are rooted in the depths of centuries, and today for us it is just folklore. Others have arisen relatively recently, when scientific rationality has already penetrated into cooking, but due to the mistakes of scientists, false conclusions have become stronger, which will circulate on the Internet for a long time. All food myths have their own logic - albeit contrary to the truth. Here are four of them, debunked a long time ago, but still popular.

Don't miss a drop

Open any book on food & science, and there will certainly be a story about the famous German scientist of the 19th century, Justus von Liebig, who, in addition to his real achievements, developed a universal theory of nutrition. It was he who launched the tenacious myth of the sealing of meat juices during the roasting process. Von Liebig believed that since meat contains both fibers and juices, they should never be lost during cooking. Therefore, the meat is best either eaten with the liquid in which it was cooked or stewed, or the juices are “sealed” by quick-frying them over the fire until they are brown, so that all the nutrients remain inside.

It sounds like a logical thing: we will close everything inside and get the maximum benefit from the meat - however, unfortunately, this is impossible. Everything is exactly the opposite. Take the meat and toss it into a hot skillet - it will sizzle and shrink. The fact is that with an increase in temperature, proteins begin to coagulate (stick together), pressing closer to each other. Because of this, some of the water is pushed out of the meat, and the higher the temperature, the drier it will become. Compare medium and well done steak, the former will be much juicier than the latter. Or even easier: place a piece of meat on a scale before and after cooking and compare how much lighter it has become. So even the fastest roasting will not keep the juices inside the steak.

Why these facts were ignored by Herr Liebig is not clear. But the words of the scientist had a lot of weight, and his idea gained recognition not only in the culinary, but also in the medical community, which began to promote "rational diets" based on Liebig's ideas. Already in the 1930s, it turned out that they were wrong, but still exposing articles about "sealing juices" by the method of 150 years ago are becoming shock content.

Chinese restaurant syndrome

The myth about meat juices has become so popular that in the future it will probably remain just a legend about the mistake of a famous scientist. But the story about monosodium glutamate is a real detective story. This is where proponents and opponents of healthy eating and monosodium glutamate, inconsistent scientists and inventors of all stripes, converged.

In 1968, a professor named Robert Ho Man Kwok wrote to the editor of The New England Journal of Medicine. He titled his letter "Chinese Restaurant Syndrome" and said that several years ago he moved to the United States and encountered strange sensations. Every time Robert ate at a Chinese restaurant, 15–20 minutes after the first course, he began to experience various ailments: numbness in the back of the neck, gradually spreading to both arms and back, general weakness, and rapid heart rate. Ho Man Kwok mentioned several ingredients that could be related to this: soy sauce, wine for cooking, monosodium glutamate (MSG), and salt. But he could not exactly name the "culprit", so he called on "friends from the medical field" to share their guesses.

This letter marked the beginning of the war that was declared against monosodium glutamate. Why exactly to him? Perhaps, from the entire list of Dr. Ho, it was this substance in the United States that was the least heard of, and therefore they were frightened and began to blame him for everything. Be that as it may, after the letter was published, other people also reported such cases, and doctors began writing in medical journals, describing similar symptoms. Soon the newspapermen also picked up this wave, and over time, glutamate was equated almost to a poison.

Everyone knows this story exactly in this form: the scientist asked the editor-in-chief a question, which then, by the will of fate, was put bluntly, although the original letter was not at all categorical. In 2013, Professor Jennifer Lemesurier became interested in the glutamate hype. "Is it possible that this whole storm has arisen because of one stupid letter?" - she thought and began to dig. After four years of investigation, Lemesurier wrote an article in which she argued that many doctors at one time considered Mr. Ho's letter a joke, but still spread this myth to laugh at the Chinese, adding fuel to the fire of racism. Over time, humor has gone from discourse, but the narrative has remained. While preparing the article, Jennifer tried to track down Dr. Ho, but found only his obituary: he passed away in 2014.

And in 2018, after the publication of Lemezurier, she received a voice message from a man who introduced himself as Howard Steele. A 96-year-old man recounted how in 1968 he had a $ 10 bet with a colleague that he would write an article for a magazine and publish it. Steele coined the character Ho Man Kwok, the name of the institute where he worked, and wrote a letter about glutamate. True, then he felt ashamed, he called the magazine and explained that this was a pure invention, but the editorial board did not publish a refutation.

The joke took on a life of its own, began to develop and resulted in a half-century hysteria against monosodium glutamate

But there were only more questions. Who, then, died in 2014 if Dr. Ho was fiction? And why did Howard Steele say that he came up with the name of the institute where he worked, if such an institution - The National Biomedical Research Foundation - really exists? There really was a certain Doctor Ho who died in 2014! Unfortunately, it was no longer possible to ask Howard Steele in more detail: on September 5, 2018, he died, leaving behind a real puzzle for researchers.

Then they began to look for the family of the real Dr. Ho and his colleagues, and they all confirmed that he was the author of the letter and wrote to the magazine quite seriously. Jennifer Lemesurier found Howard Steele's family and spoke to his daughter Anna. Her first reaction was shock, but after a couple of minutes she confessed that she believed in the story of the Ho family rather than her own father. The fact is that more than anything in the world, Howard loved to come up with such stories, and most likely, this was his last joke. He did not write a fake letter that excited the public for many years, but simply made it all up for fun. The real myth about the Chinese restaurant syndrome was launched by the real doctor Ho Man Kwok.

But unfortunately for many who claimed to be particularly sensitive to glutamate, studies have not confirmed fears about the dangers of this substance. And in general, no fears were confirmed.

The fact is that monosodium glutamate is a salt of glutamic acid, one of the amino acids from which all proteins are built

You will not be able to refuse it with all the desire.

In 1908, the Japanese scientist Kikunae Ikeda was able to isolate monosodium glutamate from kombu seaweed, patented the method for its production and found that this salt is responsible for the taste of umami (the fifth taste, besides sweet, bitter, salty and sour, which our receptors recognize). Since it is found in protein foods: meat, mushrooms, hard cheeses, soy sauce, fish, we really like it. In addition, there is a lot of glutamate in tomatoes - it's not for nothing that ketchup is so popular. If we are to give up glutamate, then first of all from these products. But you don't need to do this because MSG is safe.

In his article on glutamate, chemist Sergei Belkov says:

Glutamic acidis, one might say, a protein marker. If there is protein in food, there is usually a certain amount of this amino acid, respectively, recognition by the minds - the way the body finds food rich in protein. That is why this taste is pleasant to us, which is what the food industry uses.

According to the international codex Alimentarius food standards, glutamate does not even have an acceptable daily intake. This means that it is physically impossible to eat enough of it to hurt yourself.

Language as a map

Destroying the myth about glutamate, scientists talk about the taste of umami, and this automatically debunks another myth - about the taste map of the tongue. For a long time it was believed that there are only four tastes and they are perceived by certain areas of the tongue.

Oddly enough, this theory was born from an article that said exactly the opposite: all parts of the surface of a person's tongue perceive all kinds of tastes, just to different degrees. In 1901, the German scientist David Hoenig in his work "On the psychophysics of taste sensations" wrote that different parts of the tongue have different thresholds for the perception of tastes. However, Harvard professor Edwin Boring misunderstood it and published his translation of Hoenig's article and flavoring scheme in 1942. The tongue on it was divided into four zones, each responsible for its own taste: the tip - for the sweet, the root - for the bitter, the side parts - for the salty and sour. Then Western scientists did not know about umami, so this taste is not on the map at all.

Over time, it became clear that this is fundamentally wrong. In 1974, the American researcher Virginia Collings debunked this myth by proving that the tongue perceives tastes across its entire surface, although there is a difference in the thresholds of perception. To be convinced of this, it is enough to apply a salty solution to the tongue. But the most amazing thing is that taste buds are not only in the mouth: scientists find them throughout the body from the throat to the intestines, where, for example, there are receptors for sweet and bitter tastes.

How many times to boil water?

One of the favorite myths comes from the Soviet nuclear past: they say, you cannot boil the same water twice in a kettle, because heavy water is formed. It includes deuterium - heavy hydrogen (hence the name), but in itself it is not terrible, and in small quantities its molecules are present in any water. But the word "heavy" seems to make an impression, and people are afraid of boiling again. And they also conclude that it is impossible to mix boiled water with raw water, so as not to spoil the fresh one.

Where do the legs of this story grow from? It turns out that the famous Soviet and Russian culinary expert William Vasilyevich Pokhlebkin is to blame. In 1968, in his book “Tea. Its types, properties, use”he wrote:

“In the process of prolonged boiling, large masses of hydrogen evaporate from the water, and in this way the share of so-called heavy water D2O, where D is deuterium, increases … Heavy water naturally settles at the bottom of any vessel - a teapot, titanium. Therefore, if you do not pour out the rest of the boiled water, then with repeated boiling, the percentage of heavy water in this vessel will increase even more."

These words can be found in all articles denouncing the heavy water myth. Although this quotation cannot be found in the book itself (they say that after exposure this blunder "disappeared"), comrade Pokhlebkin really warns that "the water for brewing tea in no case should be brought to a boil", because "boiled water spoils the tea, makes the drink hard and makes it seem empty. " "Tea is especially spoiled if fresh water is added to the already boiled water, and then this mixture is boiled."

As a result, many of our fellow citizens are afraid of double boiling - but there is no need to be afraid since 1969. Then in the journal "Chemistry and Life" they published calculations: to get 1 liter of heavy water, you need to pour 2, 1 × 1030 tons of ordinary water into a kettle, which is 300 million times the mass of the Earth. If you still decide to boil yourself a glass of "heavy", you can safely use it. The human body contains deuterium, so heavy water is not harmful to us. When boiling, the concentration of salts increases due to the evaporation of water, but the water itself does not become heavy. Radioactive too.