What Is an MSG Allergy?

In the 1960s, the food additive monosodium glutamate (MSG) incorrectly gained a bad reputation because of fears that it could cause allergy-like symptoms and side effects. However, since the 1990s, researchers have largely debunked the existence of an MSG allergy.

While an MSG allergy is a myth, some claims still exist on the internet. There are also clinical studies that have assessed possible negative reactions from this ingredient, but they’re not representative of the small amounts humans typically consume in foods.

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It is possible to experience allergies to the food MSG is in, as opposed to an allergy to the additive itself. The Food and Drug Administration (FDA) also recognizes MSG as safe for consumption.

Here’s what you need to know about MSG, the rise and fall of the MSG allergy myth, and what you can do if you’re experiencing possible symptoms of a food sensitivity or allergy.

MSG is a flavor enhancer made from L-glutamic acid, which is a naturally occurring amino acid that exists in many foods. It gives what’s known as an “umami taste,“ which roughly corresponds to a savory or salty flavor.

It occurs naturally in many foods and is commonly used as a flavor-enhancing food additive in Asian dishes. It may also be added to other types of foods.

Is it the same as salt?

Table salt is an ionic compound made up of a 1-to-1 ratio of sodium (Na) and chloride (Cl) ions, through which table salt derives its chemical formula NaCl (sodium chloride). The positively charged sodium ions and negatively charged chloride ions are bound together in a solid structure by electrical attraction.

MSG also is another ionic compound that contains both positively charged sodium and negatively charged glutamate ions, but not in a 1-to-1 ratio.

The ratios are 12 percent sodium ions, 78 percent glutamate ions, and 10 percent water, which results in the chemical formula (C₅H₈NO₄^–).

Because it contains sodium, MSG is able to provide a similar savory or salty flavor to many foods.

Despite concerns, decades of research have mostly failed to demonstrate a relationship between MSG and serious allergic reactions. People have reported reactions after eating foods with MSG, but human studies haven’t supported this anecdotal information.

Is MSG safe?

The FDA recognizes MSG as “generally recognized as safe” (GRAS), which is the same category as salt and pepper.

A 2006 review of the previous 40 years of clinical literature then found no credible link between MSG and any specific symptoms or allergies. Instead, researchers who have debunked these sorts of claims encourage medical professionals to help patients look for other underlying causes of food-related symptoms.

In 2016, researchers found that any amount of MSG is genotoxic, meaning it’s damaging to cells and genetic material, as well as to human lymphocytes, a type of white blood cell. However, the study found that these effects were in vitro, meaning the tests were done in a test tube. The results don’t support the theory that eating MSG is harmful in the same way.

In 2015, researchers found possible links between renal (kidney) damage and chronic MSG consumption in animals. However, similar to the previously mentioned study, there’s no evidence that the small amounts of MSG humans consume could lead to kidney damage.

Nevertheless, further research in humans may be warranted to completely rule out sensitivity to foods with MSG.

The FDA acknowledges reports of short-term, mild symptoms reported by individuals who consume MSG without food. These symptoms may include:

• drowsiness
• headache
• skin flushing
• numbness and tingling
• heart palpitations

Still, while the existence of an allergy to MSG has largely been debunked, it’s still possible that you might have a sensitivity or allergy to the actual food containing MSG.

Food additive sensitivities are also possible.

Food sensitivity vs. food allergy

It’s important to understand the differences between food sensitivities and allergies. Also referred to as food intolerance, food sensitivity occurs due to negative reactions in the digestive system.

While you might experience uncomfortable symptoms, a food sensitivity is unlikely to cause problems if you eat the food in small amounts. The symptoms may also occur within a few hours of eating the food, but will also go away on their own.

Signs of possible food sensitivity may include:

• headache
• itchy skin
• skin rashes
• abdominal pain
• bloating
• gas
• diarrhea

Food allergies, on the other hand, are much more serious. These occur as a result of your immune system overreacting to certain foods and creating antibodies to attack them.

Unlike food sensitivity, some people might have life threatening reactions if they have severe food allergies. Symptoms develop quickly, sometimes even after just touching the food.

Symptoms of a food allergy may include:

• red skin, hives, or eczema rashes
• skin swelling
• diarrhea
• vomiting
• respiratory symptoms, such as wheezing or shortness of breath
• swelling in the throat
• anaphylaxis, a life threatening reaction that may lead to unconsciousness

If you experience any negative symptoms after consuming an MSG-containing food, it’s important to see a doctor for the next steps, including possible testing for food intolerance or allergies.

According to the FDA, consuming larger doses of MSG — 3 grams without food — has been linked to symptoms in humans.

However, not only are those portions unlikely to be found in restaurant or grocery food, it’s unlikely that anyone would consume MSG in non-food sources. The FDA says the typical MSG serving in food is 0.5 grams or less.

The best way to treat a food intolerance or allergy is to avoid the food that’s causing your symptoms. However, you may need blood or skin tests to confirm any food allergies or sensitivities before making any significant dietary changes. Your doctor may also recommend a food diary or elimination diet.

More serious symptoms, such as anaphylaxis, require emergency treatment in the form of a shot of epinephrine (adrenaline). Hospitalization may also be required.

The best treatment for a food allergy is to avoid eating that food.

What foods contain MSG?

It may be hard to avoid foods with MSG. According to the U.S. Department of Agriculture (USDA), MSG occurs naturally in many foods. It’s particularly found in high doses in food that is high in protein, such as:

• meat
• poultry
• cheese
• fish

It also exists in certain vegetables, such as:

• tomatoes
• mushrooms
• broccoli

With regard to foods that contain MSG as an additive, labeling is required when the compound is added as an ingredient. In those cases, it’s listed as “monosodium glutamate.“

Substances to avoid that may contain added MSG include:

• frozen foods
• spice mixes
• canned or dry soups or stocks, which food labels may refer to as “dried beef,” “chicken stock,” “pork extract,” or “hydrolyzed wheat protein“
• sauces and salad dressings
• meat-based foods like sausage

While there was once a belief that MSG could cause allergic reactions in some people, the overall existence of an MSG allergy has been largely declared a myth.

MSG itself naturally occurs in some foods, such as meats, and is added to other types of processed foods to help preserve flavor. While it’s possible to have either a food sensitivity to MSG or any MSG-containing foods, there’s no scientific evidence to prove that the food additive causes allergies in humans.

If you experience unusual symptoms after eating particular food items, see your doctor for possible testing. Any suspected sensitivities to MSG or MSG-containing foods may be resolved by avoiding these items altogether.