Monosodium glutamate (MSG) is a food additive that enhances flavor. It is commonly used in restaurants and pre-packaged foods.
While there are many anecdotal reports of MSG-induced symptoms, scientific research into the syndrome is limited.
As a result, the use of MSG remains controversial. Some Chinese restaurants advertise as being MSG-free.
Read on to learn more about MSG symptom complex and the health effects of this additive.
What is Chinese restaurant syndrome?
Chinese restaurant syndrome is now known as MSG symptom complex.
The term Chinese restaurant syndrome is no longer in professional use, though some people may still use the phrase to explain their symptoms.
Reported symptoms include:
- breathing difficulties
- chest pain
- facial flushing
- a headache
- numbness or burning pain in the mouth
- a rapid heart rate
- swelling of the face
Sometimes, symptoms can be severe. A case report published in the Indian Journal of Critical Care Medicine described a 23-year-old man who experienced severe swelling in the mouth after eating Chinese food. He was unable to speak and had serious difficulty swallowing saliva.
While MSG symptom complex is likely related to MSG intake, researchers are still not entirely sure what causes the symptoms.
While MSG may not affect everyone, it appears that some people are extremely sensitive to it or other food additives.
What to know about MSG
MSG is a flavor enhancer commonly added to processed meats.
MSG is made from glutamate, which is one form of glutamic acid, an amino acid that is naturally present in many foods.
The human body also produces glutamate and requires it for several functions, including learning and memory.
MSG is used to enhance flavor, and it is commonly added to Chinese food, processed meats, and canned goods.
The United States Food and Drug Administration (FDA) consider MSG to be "generally recognized as safe."
However, because the FDA have received many reports of negative reactions to MSG, the administration requires manufacturers to feature added MSG on food labels.
Relatively few studies have investigated the effects of MSG, especially in recent years.
Of those participants, 38.5 percent reacted to MSG only, 13.1 percent reacted to the placebo only, and 14.6 percent reacted to MSG and the placebo.
The reactions were typically mild. An increased dose of MSG without the presence of food was most likely to cause a reaction.
However, the researchers were unable to replicate the results when they repeated the test with the same of participants. This suggests that outside factors, such as food intake, may have caused the reactions.
In 2016, a review of studies concluded that eating MSG with food had no significant influence on the occurrence of headaches.
However, one study included in the review reported a significant link between the consumption of MSG and headaches in female participants.
The authors concluded that, overall, the methods used could not produce reliable, consistent results and that more research is needed.
It is important to note that an organization that promotes the use of glutamate employs one of these authors.
Researchers commonly administer MSG to mice to induce obesity. In the past decade, some people have wondered whether MSG intake is also linked to extra weight in humans.
More research is needed to determine the effect of MSG on the body.
People report various health issues that they associate with MSG. According to a Korean study from 2014, the most common complaints were:
- thirstiness (84.5 percent)
- drowsiness (55.7 percent)
- weakness (34.5 percent)
- nausea (30.2 percent)
- a headache (14.7 percent)
MSG symptom complex may also cause:
- excessive sweating
- flushing of the skin
- a tingling sensation in the skin
- numbness or burning in the mouth
Severe and life-threatening symptoms are rare. They resemble the symptoms of an allergic reaction and include:
- chest pain
- difficulty breathing
- an irregular or rapid heartbeat
- swelling in the throat or face
People who experience severe symptoms should seek emergency medical attention.
The treatment for MSG symptom complex varies, depending on the symptoms and their severity.
Mild symptoms typically clear up without treatment. A person with these symptoms may benefit from:
- drinking water to stay hydrated
- drinking ginger or peppermint tea to reduce nausea
- taking over-the-counter (OTC) pain relievers, if a person has a headache
A doctor may recommend OTC or prescription medications to relieve these symptoms. Treatments include:
ïantihistamine medications for breathing problems, facial swelling, or an abnormal heartbeat
ïa shot of epinephrine (adrenaline) for life-threatening reactions
MSG is usually present in potato chips.
The only way to completely prevent MSG syndrome complex is to stop eating foods that contain the additive.
People with very mild symptoms may be able to prevent them by only eating small amounts of foods that contain MSG.
Anyone with a sensitivity to MSG should check whether it is included on food labels. Remember to also check for the full name: monosodium glutamate.
The additive is usually present in:
- packaged and processed meats, such as hot dogs
- meat extracts, such as pork extract
- canned vegetables
- potato chips
- soups and stocks
MSG is also known as:
- hydrolyzed protein
- modified food starch
Some people prefer to eat at Chinese restaurants that are MSG-free. Other kinds of restaurants also use MSG, so it is essential to ask before ordering food.
Avoiding natural glutamate
People who are very sensitive to MSG may also need to avoid foods that contain high amounts of natural glutamate.
Natural glutamate is present in the following:
- mature cheeses
- cured meats
- braised meats
- bone broths
- fish and shellfish
- fish sauce and oyster sauce
- soy protein
- soy sauce
- ripe tomatoes and tomato juice
- grape juice
- yeast extract
- malted barley, which is used in beer and bread
Avoiding natural glutamates may be challenging, but a doctor or dietitian can provide guidance and develop a low-glutamate meal plan.
When to see a doctor
A person should see a doctor if symptoms are severe or persistent.
Anyone with breathing difficulties, chest pain, or swelling of the throat should seek emergency medical care.
To assess a person's symptoms, a doctor may ask:
- when the person last ate Chinese food
- if the person has recently eaten any foods that contained MSG
Depending on the symptoms, the doctor may also:
- check the heart rate
- examine the airways for blockages
- perform an electrocardiogram to check for an abnormal heart rhythm
The effects of MSG syndrome complex usually pass quickly. People often feel better within a few hours.
In the meantime, home remedies can alleviate discomfort.
However, anyone with a life-threatening reaction to MSG should carry an epinephrine shot, such as those sold under the brand names Adrenaclick or EpiPen. Be very careful when eating out or buying packaged or processed foods.
A dietitian can help to determine which foods are safe.