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MSG Sensitivity (Intolerance): Causes, Symptoms and Treatment

Monosodium glutamate (MSG) can be found as a flavor-booster in many packaged foods and restaurant dishes where it enhances the taste of food by stimulating nerves on the tongue and in the brain. It is especially popular in Asian cooking but is also commonly used in processed meats, canned vegetables and clear soups.

Monosodium glutamate is the sodium salt of glutamic acid, a white, crystalline salt-like substance. The body uses the carboxylate anion of glutamic acid known as glutamate to help transmit messages within the brain. Glutamate is present in all foods that contain protein.

MSG is made from fermenting sugar beets, sugar cane, corn, molasses or tapioca and is considered a safe additive by the FDA when “consumed at customary levels”. The FDA stated that no evidence exists to suggest that MSG causes the brain damage that could trigger Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis or any other chronic disease. However, some people are sensitive to MSG and some critics believe that MSG is an excitotoxin, which contributes to a number of long-term conditions affecting the brain.

The FDA further stated that people who chronically suffer from adverse reactions to MSG are “MSG sensitive” or “MSG intolerant”, a condition called MSG symptom complex (sometimes also referred to as Chinese restaurant syndrome).

Research shows that people who suffer from allergies or severe asthma may be susceptible to MSG sensitivity. Some studies have also found that patients with asthma may have more severe asthma attacks after ingesting MSG.

MSG intolerance is not considered an allergy, because it does not involve a reaction by the immune system. As with all food sensitivities, the best way to treat MSG sensitivity (or intolerance) is to avoid MSG.

Causes of MSG Sensitivity

It is not exactly understood why monosodium glutamate causes symptoms in some people. MSG is a glutamate, a type of amino acid naturally occurring in various foods. Glutamate is a neurotransmitter in the brain, involved in cognitive functions such as memory and learning.

At the core of the scientific debate is whether the body processes monosodium glutamate the same way as it does natural glutamate. Some experts believe that both are digested the same way and, therefore, MSG poses no health risk. However, critics of MSG argue that it can be harmful, though there is no sound scientific evidence that the body treats MSG differently from natural glutamate.

But, some individuals do have a sensitivity to monosodium glutamate which may arise after eating MSG over a period of time. People who have asthma or allergies may be more prone to an adverse reaction to MSG.

Symptoms of MSG Sensitivity

Some individuals react immediately after ingesting food that contains monosodium glutamate while others may experience symptoms up to 48 hours later. Reactions vary from patient to patient, while more than one symptom can be experienced at the same time. We do not know yet whether adverse reactions to MSG exacerbate underlying health problems, or if cumulative effects are created after consuming it over a period of years.

While symptoms may appear similar, MSG sensitivity is not a true food allergy as there is no immune system response. MSG sensitive people report experiencing both, short-term and long-term health effects. Some individuals have mild and temporary symptoms such as sweating or flushing, and long-term symptoms ranging from fatigue on one hand to hyperactivity on the other. Hence, symptoms of MSG sensitivity may include any of the following:

  • Angina
  • Bloating
  • Breathing difficulty (asthmatics)
  • Burning or numbness in the back of the neck
  • Burning or numbness inside or around the mouth
  • Chest pain
  • Depression
  • Diarrhea
  • Drowsiness
  • Facial pressure or tightness
  • Fatigue
  • Flushing
  • Headache
  • Heart palpations
  • Heartburn
  • Hives
  • Hyperactivity
  • Insomnia
  • Joint pain
  • Migraine
  • Nausea
  • Neurological disorders
  • Rapid heartbeat
  • Rash
  • Runny nose or congestion
  • Seizures
  • Shortness of breath
  • Sweating
  • Tingling, warmth and weakness in the face, temples, neck, arms and upper back
  • Weakness

The most serious, but rare, symptom not listed above is anaphylaxis, which involves two or more body systems, and requires immediate medical attention.

Diagnosing MSG Sensitivity

At the moment, there are no established methods of diagnosing monosodium glutamate sensitivity.

Treatment of MSG Sensitivity

If monosodium glutamate is suspected to be the cause of any symptoms mentioned above, it is best to avoid MSG in processed foods and restaurant meals and seek a doctor’s care.

Since avoidance is the only treatment, patients should inquire about the ingredients in restaurant dishes and better avoid Asian restaurants. They should also read food labels carefully to avoid consuming products that contain MSG.

As required by the FDA, monosodium glutamate is listed on the label of any food to which it is added. However, there are also other chemically distinct glutamate additives that may in some sensitive individuals induce similar symptoms. They include:

  • Autolyzed yeast
  • Calcium caseinate
  • Hydrolyzed protein
  • Maltodextrin
  • Modified food starch
  • Monopotassium glutamate
  • Sodium caseinate
  • Textured protein

Patients should keep in mind that MSG can be also found in dietary supplements, medications, cosmetics and personal care products and they should, therefore, seek advice from their doctor regarding these products.