MSG ≫ 정미료, 역할, , 논란

MSG : FAQ 흔히하는 질문들

Last update June 29, 2011 Global Task Force
International Glutamate Information Service

General Information on Glutamate
1. What is glutamic acid?
Glutamic acid is a non essential amino acid with a 5-carbon structure involved in many metabolic reactions. Around 50 g of glutamic acid a day is turned over in the body (in a 70 kg body weight).

2. How we can find glutamic acid in nature?
Glutamic acid can be free or bound with other amino acids to form proteins in plant and animal tissues.
Free glutamic acid that does not bind to other amino acids can be found in small amounts in tissues and plants or come from the breakdown of proteins. Glutamic acid can lose a proton from the acid radical at physiological pH becoming negatively charged. In this form it is called glutamate and promotes umami taste.

4. What is the difference between MSG and naturally occurring glutamate?
MSG and glutamate only differ in the content of sodium. The glutamate of MSG is the exact chemical compound of naturally occurring glutamate in foods. They have the same chemical name because they are chemically identical and therefore have the same taste.
What does it mean that MSG and free glutamate have the same taste? It means that umami receptors on our tongue can not distinguish between glutamate from MSG and free glutamate from other food ingredients.

5. Then, why to make a distinction between MSG and naturally occurring glutamate?
The fact that some consumers prefer to get umami taste from naturally occurring glutamate rather than from MSG is a personal preference. In our body, our cells and their receptors, transporters and enzymes cannot differentiate glutamate by their origin. Their interaction is based on chemical identity*.
*Attention: subjects that believe to have intolerance against glutamate, be aware that this intolerance applies to ALL 2
sources that contain glutamate, from MSG and from other food ingredients. Since all proteins contain glutamate and naturally occurring glutamate is widely spread in many kinds of foods, appropriate dietary assessment may be advised. (Medical certainty on MSG intolerance is not scientifically established)
Glutamate intolerance has not been definitely demonstrated up to date using gold standard clinical studies (look at MSG & health for more detailed information).

6. How much sodium there is there in MSG?
12% of the total molecular weight of MSG is sodium; considerably lower than the 39% in table salt. With 1 gram of table salt, we add roughly 3 times more sodium than with 1 gram of MSG. With the right amount of MSG and salt, it is possible to decrease in a dish the amount of salt up to 30% without compromising its taste.

7. Where does MSG originally come from?
The commercial production of MSG started in 1909 by a method patented by professor Kikunae ikeda. This method consisted on the extraction of glutamate from hydrolyzed vegetable proteins; so MSG has been used for more than 100 years in Japan to round the taste of many dishes.

8. How is MSG made?
To manufacture MSG requires the production of glutamic acid first with the later addition of sodium.
Glutamic acid is produced through the fermentation of corn, sugar beet, sugar cane or cassava in a similar process to beer, soy sauce, vinegar, yogurt or even chocolate. And at the end, sodium is added through a process called neutralization. The final product, MSG, is an odorless and crystalline powder, freely soluble in water but not hydroscopic.

Curious Science
Do you know…?
1. Do you know how much glutamate we consume every day?
Every day we eat from 8 to 10 grams of glutamate assuming that proteins contain 8 to 10% of glutamate; independently of being from plant or animal in origin (protein intake in Western diets is about 100 gram per day). Only 1 to 5 grams in our diet correspond to free glutamate, either from added MSG (0.5-3 grams) or from other foods. At the end, it is impossible to have a glutamate free-diet.

2. Do you know why we like umami taste?
Experts are still investigating the physiological importance of umami taste, but preliminary data seems to indicate that umami facilitates protein digestion in the stomach and amino acid absorption in the intestine. Babies are born with the ability to prefer umami taste and breast milk is a rich source of glutamate. So we have evolved to prefer this taste because umami substances may contribute to a better intestinal function and in turn a better nutritional status.
3. Did you know we perceive umami taste better with lower-fat dishes?
Fat seems to mask umami taste. Traditional Japanese food uses a stock (dashi) from seaweed and dried bonito that has no fat and a very clear umami taste. When fat is low, the authentic tastes and flavours of ingredients become clearer.
4. Do you know how our body treats glutamate?
First, we taste glutamate as umami in the mouth after it binds to umami receptors. When food reaches the stomach, glutamate
4
seems to improve the efficiency of protein digestion; and finally, in the intestine, glutamate is transported inside the cells where is used as energy for the transport of other amino acids and glucose.
MSG in Food
1. In which dishes and with which ingredients can we use MSG?
MSG mixes well with meat, fish, poultry, vegetables, sauces, soups, and marinades, and it is used in a wide variety of food industries including, but not limited to, cheese, meats, snacks, noodles, frozen foods, etc.
2. How MSG is used?
MSG can be found as a common seasoning to either mix during cooking or sprinkle on dishes, or in several foods MSG is directly included in the manufacturing process.
3. Why use MSG?
MSG is used to get a balanced, rich and delicious taste. It is a basic umami compound and the simplest and most direct way to add umami to dishes. MSG has the same effect as foods with naturally occurring glutamate such as cheese, soy sauce or ketchup.
What is the advantage of using MSG versus other food ingredients?
MSG does not add additional flavors like tomato or seaweed kombu, so it allows to introduce only umami taste without changing the character of the dish itself. It is also useful to obtain a reliable and standard taste. The content of umami substances in food ingredients vary greatly with seasons and maturation.
Additional applications of MSG

1. To reduce the content of salt
Taking advantage of the properties of MSG, health experts are exploring the usage of MSG to reduce salt in foods. MSG has roughly 3 times less sodium and provides a more agreeable taste than salt. It can be used then to decrease the level of sodium without diminishing the taste acceptability of lower-salt foods.
Why to reduce salt?
Salt is sodium chloride and in most countries, sodium consumption (3,400 milligram average per day in the U.S.) exceeds the maximum intake recommended by dietary guidelines (2,300 milligram per day). An excess of sodium can predispose some individuals to hypertension, a major risk factor for heart diseases and stroke. So there is a general need to lower the salt content in foods.
Can MSG increase my sodium intake?
If MSG is used in addition to salt, it can, but its contribution is small. How small? It depends on the added amount, but considering all sources of sodium-containing ingredients, processed foods, drinking water, and pharmaceuticals, MSG typically contributes to 1 or 2 milligrams of sodium each 100 milligrams in the diet; or 34-68 milligrams in the total estimated 3,400 milligrams.
How can I reduce my salt intake with MSG?
By replacing some of the salt for MSG. If 30 % of salt is substituted by MSG, sodium drops around 20 % and foods are still pleasant to eat. Thanks to sensory evaluation studies we know that the substitution of 30 % of salt with MSG allows salt reduction without compromising the overall taste of the dish. 6

2. Low-fat foods
Fat, which gives a rich and satisfying taste, is responsible for an increase of total caloric intake in western diets. Low fat dishes with a low caloric density (number of calories in 1 g of food) can still be satisfying with MSG. The Japanese cuisine stands out because relays heavily on umami taste ingredients that have a very low fat content (low caloric-density) and are satiating at the same time.

Look MSG & Health to understand more about obesity
Obesity
4. Can MSG mask the taste of poor quality ingredients?
MSG adds umami taste to food, but it cannot turn poor flavour quality ingredients into the Roll-Royce of flavour. The final perception of a dish depends on the balance of tastes and smells, among other more complex properties such as texture, temperature, appearance, expectations, etc.

5. How much is too much MSG?
The taste of MSG is self-limiting. This means that MSG increases the pleasantness of savory taste only when it is used within a narrow concentration range, like salt or vinegar. In a clear soup, MSG is pleasant between 0.2 and 0.8 g per 100 ml (0.2-0.8 %). Depending on the food, MSG becomes quickly unpleasant at a concentration higher than 2%. So, it is not true that the more MSG we add the better the taste. It has been proven by sensory evaluation studies that an excess of MSG makes food unpleasant.

6. Do Japanese get glutamate from seaweed kombu?
Only top Japanese chefs use kombu as a source of glutamate to make dashi stock and add umami to their dishes. Kombu is an expensive and a limited natural resource so most households in Japan use MSG and premix seasonings with MSG to get the same effect. Fermentation is a more efficient and environmentally friendly way to obtain MSG. Moreover, not all dishes combine well with the flavour of kombu and not everyone enjoys its strong sea aroma.

7. Since when humans have used umami seasonings?
There is a long history; seasonings rich in glutamate were traditionally made and used already in ancient Rome like the fish sauce called garum. They used garum to add umami taste in their dishes, even though they did not realize it then. Today there are many food sources of umami seasonings around the world, such us fish sauces and pastes as well as fermented bean products. Southeast Asian fish or shell-fish products are made today in a similar way to garum and bean pastes and sauces are generally made of a mixture of salted beans, cereals and fungi.

MSG & Health
1. Is MSG safe?
Like any food substances including water, the safety of MSG depends on the amount and the context in which MSG is used. If the question is whether MSG is safe when it is added to dishes for a pleasant-savory taste when cooking, the answer is yes. But MSG is not intended to be injected or swallowed pure in extremely high concentrations without food, neither are other food substances. We discuss below the main topics that have undermined the safety of MSG.

2. Why MSG safety has been questioned?
The safety of MSG has been questioned because of two main historical developments
1. Because of the lack of knowledge and experience with umami taste. Umami taste has remained unknown for most of the 20th century and its understanding has proven essential to recognize the function of MSG and glutamate in foods.

2. Because of a progressive specialization of science. Specialization has brought experts to study our body on isolated compartments. Today, fewer specialists understand the function of our body as a whole. MSG had been especially controversial in the field of neuroscience because glutamate is one of the most abundant neurotransmitters in our brain. So even today, there is the erroneous assumption that the glutamate in food affects the brain, linking directly MSG with brain function. But by focusing only on the brain it is difficult to appreciate that the gut is the most effective, physical and metabolic barrier against what we ingest. Moreover, the brain is completely isolated from the rest of the body by a structure called blood-brain barrier. This way, the brain isolates itself against the glutamate we make and release from our own tissues.

3. Can we detect, make and use glutamate in our body?
Glutamate is a basic molecule in biology. We and other species have clearly evolved to detect and use glutamate in our tissues. Everyone has umami receptors on the tongue besides glutamate transporters and metabolic enzymes to synthesize and use glutamate for energy in most tissues. Receptors, transporters and enzymes cannot distinguish between glutamate of MSG and glutamate from foods because the recognition is based on its chemical structure which is identical.

4. When has MSG become controversial?
In the late 1960’s when two publications shed some doubt about the safety of MSG.
The first one was a 1968 letter to the editor that a Chinese American doctor, Dr. Kwok, wrote to The New England Journal of Medicine. In this letter, he described a series of self reported symptoms after having a meal in a Chinese restaurant: numbness of the back, general weakness and palpitations. Dr. Kwok called these symptoms “Chinese Restaurant Syndrome” and blamed ingredients like alcohol from cooking wine, salt or MSG.
The second publication was a 1969 report in which very large doses of MSG were injected into newborn mice causing brain lesions. Nowadays, the weight of scientific evidence does not support the contention that the use of glutamate as seasoning can lead to brain damage.
When those reports were published, MSG had been used for 59 years in Japan as a food seasoning already without any claims of adverse effects. It is also interesting to consider that we eat every day and have been eating since the beginning of our civilization many foods rich in glutamate to make our foods taste better.

5. Did Dr. Kwok further explain his claims later?
Dr. Kwok never published any article about the issue again and none of the other ingredients used in U.S. Chinese restaurants have ever been investigated. Instead, other researchers published reports supporting that MSG was the cause of CRS. Thus, MSG was made automatically responsible of the list of unspecific symptoms described by Dr. Kwok and other researchers. With time, the list has expanded but the reports that have tried to find a link between MSG and CRS have been criticized because of technical flaws such as the fact that the taste of MSG is easily recognized by subjects invalidating the study. CRS seems to respond to a variety of no specified post-ingestive illness since rigorous scientific studies have not been able to associated directly MSG to CRS.

6. MSG has been blamed for many diseases; is it true?
Many diseases with unknown causes have been blamed on MSG based on believes and perceptions against MSG without scientific evidence. And those perceptions against MSG spread also among the scientific community. Because the mechanisms of those diseases are not well understood, it is impossible to demonstrate or reject the involvement of MSG scientifically.
What is a fact is: first, MSG and glutamate are ubiquitous in our daily foods and bodies, so life without glutamate is not possible, and second, foods that don’t taste good are incompatible with a sustainable nutrition because we would refuse to eat unpleasant foods.

7. Are self reported symptoms enough to question the safety of MSG?
Self reported symptoms are not a scientific method. Our perception and the perception of scientists can be influenced by many factors, so medical science has created a gold standard method to test the cause-effect of substances: double blind with placebo control. Double blind means that neither subjects nor scientists who conduct the study know whether the test substance, in this case MSG, is MSG or placebo. And placebo is a neutral sample that does not affect the test and works as a control to compare the effect of MSG.

8. Has MSG been thoroughly studied using the scientific method?
There have been several studies using a thorough scientific method. These studies have demonstrated:
1. MSG in foods does not cause any adverse effects 11
within the range of the pleasant-savory taste (0.5-1.5 g/100 g).
2. Only when MSG is ingested ALONE and with an EMPTY STOMACH at a large single dose of 3 to 5 g (which goes beyond the pleasant umami taste) may cause adverse symptoms in certain subjects. These adverse symptoms were not observed when MSG was given with food even in subjects that responded to MSG with empty stomach and were not life threatening. What is more unsettling is that symptoms have proven to be unpredictable; every MSG challenge gives a different symptom, so they do not appear to be reliable.
3. In real life, nobody ingests 5 g of MSG at once with an empty stomach when having a meal. The extremely unpleasant taste will stop us from taking this highly concentrated MSG the same way we will reject extremely high-salt or very bitter foods.

9. What the international and national scientific advisory bodies of regulatory agencies have to say about the safety of MSG?
International and national bodies that evaluate the safety of food additives have decided that MSG is safe and can be regularly consumed by humans.
Those bodies are organizations like the Joint FAO/WHO Expert Committee of Food Additives (JEFCA) for the Codex Alimentarius Commission, the Federation of America Societies for Experimental Biology that advices the U.S. Food and Drug Administration (FDA), the Scientific Committee for Food of the European Comunity or the Food Standards of Australia New Zealand.

10. How much MSG do we usually consume every day? 12
In average, individuals consume with proteins between 110 and 140 milligrams (mg) of total glutamate per kilogram (kg) of body weight per day from which 5 (U.S.) to 40 (Asian countries) mg comes from MSG.

11. How much glutamate do babies ingest?
Breast milk is rich in glutamate. It contains from 161.5 mg/dL to 230.0 mg/dL of free and protein bound glutamate. Babies fed exclusively with breast milk ingest 36 mg of free glutamate per kg/ body weight every day, and 360 mg/ kg of body weight of protein-bound glutamate per day.
Most infant formulas are completely depleted of free glutamate and babies fed exclusively with these milks do not experience umami taste the same way breastfed babies do. This could lead later to problems on taste preference and food acceptance.

12. Can pregnant women and infants eat MSG?
MSG is safe for expecting mothers and infants. Mothers are already eating proteins with glutamate and have been eating them since humans exist, as well as free glutamate from a variety of foods. And babies relay completely on breast milk, which is one of the richest food sources of glutamate. During pregnancy, the placenta metabolizes glutamate to obtain energy, like other cells in the mother’s body. Also babies can metabolize glutamate normally. MSG is just another form of glutamate that imparts umami taste.

13. How much glutamate there is in our body?
Within our organs like liver, muscles and kidneys we store around 1.4 kg of glutamate, and 41 grams of glutamate are turned over every day. This means that 41 grams of glutamate are synthesized and metabolized in a person of 60 kg. Only 17 grams of glutamate is free in our body, mostly inside our cells.
Blood contains a very low concentration of glutamate.

14. Am I allergic to MSG?
MSG is too small to induce allergy. Allergy starts with the recognition of at least 10 to 13 amino acid-peptide known as allergen by one type of antibodies called IgEs, and neither sodium nor glutamate are capable of activating IgEs. If glutamate or sodium could cause an allergic reaction, our health would be gravely and quickly compromised since both sodium and glutamate are abundant and move freely among tissues. Confirming what we have already known from immunology, well designed studies that followed the scientific method have shown no direct link between MSG and allergy. Some talk about MSG and allergy because the general public tends to confuse allergy with intolerance.

15. Does MSG make me fat?
MSG by itself does not explain the very complex mechanism of obesity. We become fat when we intake more calories than our body can burn. The key point in body weight management is the caloric density (CD) of our diet. The CD of a food refers to the number of calories in 1 gram of that food. Usually vegetables and fruits have the lowest CD (0.44 calories per gram of carrots), whereas meats and fried foods have the highest (5.56 calories per gram of bacon). Thus, it is easier to intake too many calories by eating high CD foods because with only a small amount we can easily overpass our caloric needs without feeling satisfied. In contrast, we can have a deliciously pleasant low CD vegetable dish combined with an umami sauce that can fill our stomach and satisfy our appetite without adding too many calories to our diet.
Thus, MSG is not the reason that modern societies are getting fatter; inactivity and high CD food intake are to blame. MSG has been consumed for more than 100 years, whereas obesity is a recent health problem.

16. Does MSG contain gluten?
MSG is gluten free.

17. I’ve read that glutamate is neurotoxic, what does it mean?
Neurotoxicity it is a technical term within neurobiology. After a stroke, trauma or degenerative diseases, when neurons die or there are genetic or endogenous anomalies in glutamate metabolism in neurons, an excess of the neurotransmitter glutamate accumulates between cells (synapses) and glutamate locally damages nearby neurons aggravating the initial condition.

18. Does this mean that MSG or glutamates can damage my brain?
The neurotoxicity of synaptic glutamate refers to a malfunction or injury of the brain independently of the glutamate of the diet. To date, no study has been able to find a direct link between the chronic or acute consumption of MSG to neurodegenerative disease mediated by neuronal glutamate.
Why there is no link between dietary glutamate and the synaptic glutamate in the brain?
1. Because dietary glutamate is taken by glutamate transporters into intestinal cells where is metabolized to make other amino acids and obtain energy, so a very small amount of glutamate from the diet goes to the bloodstream.
2. Because the brain has multiple mechanisms to ensure neuronal function and isolate itself from the rest of the body. If the brain were easily hijacked by dietary glutamate, neurons could not efficiently communicate with each other since glutamate is essential for memory formation among many other brain functions.
3. If glutamate were so dangerous as to compromise the normal function of our brain, we would not have evolved to prefer but rather to avoid umami taste. The fact that we seek and enjoy the pleasantness of umami taste rather demonstrates that umami substances are advantageous to our survival.