Monosodium glutamate (MSG) is a controversial food additive that people use to enhance flavor. Many people associate it with Asian cuisine, though it is an ingredient in a variety of foods, including processed meats, soups, and fast food.

Historically, many people have believed that MSG can lead to various health conditions.

However, the Food and Drug Administration (FDA) says that MSG is generally safe to consume. In fact, it is already naturally present in the human body.

This article will examine the reasons that people may consider MSG harmful and give science-backed evidence as to whether or not these assumptions are accurate. It will also list some of its uses and known health effects.

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MSG stands for monosodium glutamate. This is a form of glutamic acid, which is an amino acid that is present in many different natural foods.

Glutamic acid performs many functions in the body, such as forming proteins.

Glutamic acid is a precursor for the neurotransmitter gamma-aminobutyric acid (GABA). GABA is abundant in the nervous system and plays a vital role in inhibition, or signal calming.

The FDA classifies MSG as generally safe.

There is not enough evidence to support a link between MSG consumption and the adverse reactions that people have reported. Researchers cannot conclusively say that MSG has caused the reactions in these reports.

The FDA asked the Federation of American Societies for Experimental Biology (FASEB) to investigate adverse reactions to MSG.

The FASEB stated that adverse reactions could only be possible in people who may have sensitivities and who have consumed more than 3 grams (g) of MSG.

Since a typical serving of food with MSG contains only 0.5 g of MSG, reactions are unlikely following typical meals.

MSG is a bright, white powder similar to salt.

In 1908, a professor at the University of Tokyo in Japan extracted MSG for the first time from seaweed.

Manufacturers now typically produce it by fermenting starch, sugar cane, or molasses. This fermentation process is similar to the method that people use to make vinegar, wine, and yogurt. It naturally produces MSG, which manufacturers then purify and dry.

The resulting crystalline structure dissolves readily during cooking to enhance the flavors of the dish.

According to one 2017 study, people have been using MSG to season their food for over 100 years.

Some people in Japanese cultures consider MSG, or umami, to be one of the five basic tastes. Many dishes featured in Japanese, Chinese, and South Asian cuisine use MSG.

According to one 2018 study, the following food products may also contain MSG:

  • frozen meals and processed meats, such as:
    • bacon
    • pastrami
    • pepperoni
    • sausages
    • lunch meats
    • smoked meat products
    • hamburgers
    • cold cuts
    • salami
  • sauces and dressings, such as:
    • ketchup
    • mayonnaise
    • barbecue sauce
    • salad dressing
    • soy sauce
    • mustard
  • soup bases, such as bouillon cubes and granulated powders
  • snacks, such as potato chips
  • seasonings
  • spices
  • bodybuilding protein powder
  • fast food, such as:
    • chicken nuggets
    • burgers
    • fried chicken

The first mention of MSG potentially being harmful to human health was in a letter that a Chinese physician sent to the New England Journal of Medicine in 1968. The physician said that he had noticed palpitations and numbness in his neck, back, and arms after he had eaten Chinese food.

The New England Journal of Medicine dubbed this “Chinese restaurant syndrome.” This term is now outdated, and people use the term “MSG symptom complex” instead.

Despite the author mentioning that his symptoms may have been the result of a number of dietary factors — including sodium, alcohol, and MSG — the publication highlighted MSG as being the main cause.

Over the years, people have proposed many different reasons as to why MSG may be harmful to human health.

However, there is not always enough scientific evidence to prove that these claims are true.

Brain damage

The belief that MSG can cause brain damage may have stemmed from a study in 1969 that investigated the effect of injecting large doses of MSG into newborn mice.

The investigators noted that the MSG caused neuronal cell death in several areas of the developing brain. For example, the MSG damaged the hypothalamus, which plays a crucial role in maintaining homeostasis.

However, it is not possible to compare the effects of injecting large amounts of MSG into newborn mice with the effects of humans ingesting small amounts of MSG from food into their gastrointestinal tract.

Therefore, this study does not provide enough evidence to support this claim.

Obesity

Some people believe that MSG can cause obesity.

One 2011 study that involved more than 10,000 Chinese adults concluded that MSG caused the participants to gain weight even in the absence of processed foods or a lack of physical exercise.

However, a 2017 systematic review that mentioned this study goes on to say that this result may be due to the fact that MSG may influence a person to overeat.

Moreover, a 2010 study concluded that MSG does not cause obesity at all.

It is worth mentioning that because MSG makes food taste better, people may be more tempted to overeat.

Learn what a person should weigh for their height and age here.

Headaches

Many people say that they experience headaches after eating foods containing MSG.

However, one 2016 review stated that there is no evidence to support a link between MSG consumption and headaches.

Previously, the International Headache Society mentioned MSG in their list of headache triggers. In 2018, however, they removed MSG from this list.

Learn about some possible causes of headaches here.

Cancer

Historically, some people believed that there was a link between MSG consumption and cancer risk.

However, a 2017 systematic review stated that since the 1960s, there have been no studies that have confirmed this link.

Learn more about how diet affects cancer risk here.

Asthma

Some people have reported experiencing asthma episodes after eating MSG.

One older 1987 study appeared to confirm this. The researchers gave 32 people large doses of MSG, and 40% of them later experienced an asthma episode.

However, more recent studies — such as one 2012 study into the link between MSG, diet, and asthma in adults and one 2012 study into MSG and asthma in adults and children — have found no correlation between asthma and MSG consumption.

It is also worth mentioning that studies involving high doses of MSG may not be reliable in a real-life setting. According to the FDA, it is unlikely that a person will consume enough MSG from food to experience any adverse reactions.

Learn more about asthma triggers here.

MSG sensitivity

One 2019 review mentions that some people have reported being hypersensitive to MSG.

The New York Allergy and Sinus Centers have stated that this is a sensitivity rather than an allergy. Symptoms of this may include:

The amount of MSG in food would not be enough to cause a serious adverse reaction.

Alleged hypersensitivities to MSG are only based on people’s reports. According to the 2019 review above, there is not enough solid evidence to confirm that a hypersensitivity to MSG exists.

The review called for more studies into sensitivities involving both naturally occurring MSG and added MSG.

Despite this, if a person feels that they may have an MSG sensitivity or notices symptoms after eating food containing MSG, they should stop eating it. Keeping a food diary may also help.

Learn about MSG symptom complex here.

MSG occurs naturally in food and in the body. Some manufacturers add it to food, such as fast food, to improve flavor.

Many reputable organizations over the world, including the FDA, state that MSG is safe to eat.

Historically, there have been reports of various adverse reactions to MSG. However, there is not enough evidence to support this.

Studies that have found links between MSG and certain health concerns have used amounts of MSG that a person is unlikely to consume as part of a meal.

If a person does feel that they have a sensitivity to MSG, they can stop eating it.