The Dangers of Monosodium Glutamate
Food Additive Commonly Marketed as a Flavor Enhancer

The Dangers of Monosodium Glutamate (MSG)
Food Additive Commonly Marketed as a Flavor Enhancer

White crystalline substance, a sodium salt of the amino acid glutamic acid. MSG is used to intensify the natural flavour of meats and vegetables. It elicits a unique taste, called in Japan umami, different from the four basic tastes.

Originally derived from seaweed and first used in Japan in 1908, it has become a common ingredient in Chinese and Japanese cooking.

MSG in large amounts may have physical effects, including an allergic reaction commonly called "Chinese restaurant syndrome."

Monosodium glutamate, also known as sodium glutamate and MSG, is a sodium salt of glutamic acid, a naturally occurring non-essential amino acid.

It is used as a food additive and is commonly marketed as a flavour enhancer. It has the HS code 29224220 and the E number E621.

Trade names of monosodium glutamate include Ajinomoto, Vetsin, Ac'cent and Tasting Powder. It was once made predominantly from wheat gluten, but is now made mostly from bacterial fermentation; it is acceptable for coeliacs following a gluten-free diet.

Although traditional East Asian cuisine had often used seaweed extract, which contains high concentrations of glutamic acid, it was not until 1907 that MSG was isolated by Kikunae Ikeda. MSG was subsequently patented by Ajinomoto Corporation of Japan in 1909.

In its pure form, it appears as a white crystalline powder that, as a salt, dissociates into sodium cations and glutamate anions while dissolving (glutamate is the anionic form of glutamic acid).

There are health concerns about the use of monosodium glutamate in food, but few are scientifically supported.

In April 1968, Robert Ho Man Kwok wrote a letter to the New England Journal of Medicine, coining the term "Chinese restaurant syndrome".

In this letter he claimed:

I have experienced a strange syndrome whenever I have eaten out in a Chinese restaurant, especially one that served northern Chinese food.

The syndrome, which usually begins 15 to 20 minutes after I have eaten the first dish, lasts for about two hours, without hangover effect.

The most prominent symptoms are numbness at the back of the neck, gradually radiating to both arms and the back, general weakness and palpitations...

In 1969 the "Chinese restaurant syndrome" was attributed to the flavor enhancer glutamate largely due to the widely-cited article "Monosodium L-glutamate: its pharmacology and role in the Chinese Restaurant Syndrome" published in the journal Science.

The syndrome is often abbreviated as CRS and also became known under the names "Chinese food syndrome" and "monosodium glutamate symptom complex." Symptoms attributed to the Chinese restaurant syndrome are rather common and unspecific. 

They have included burning sensations, numbness, tingling, feelings of warmth, facial pressure or tightness, chest pain, headache, nausea, rapid heartbeat, bronchospasm in people with asthma, drowsiness, and weakness.

Additional studies that have looked into whether MSG causes obesity have given mixed results. There have been several studies investigating an anecdotal link between MSG and asthma; current evidence does not support any causal association.

Since glutamates are important neurotransmitters in the human brain, playing a key element in learning and memory, there is ongoing study by neurologists about possible side–effects of MSG in food but no conclusive studies saying there are any connections.

While many people believe that monosodium glutamate (MSG) is the cause of these symptoms, an association has never been demonstrated under rigorously controlled conditions, even in studies with people who were convinced that they were sensitive to the compound.

Adequately controlling for experimental bias includes a placebo-controlled double-blinded experimental design and the application in capsules because of the strong and unique after-taste of glutamates.

A 2002 study found that rats fed on diets supplemented with 10% and 20% pure monosodium glutamate suffered retina degeneration, possibly through glutamate accumulation in the vitreous humor. However, such extreme amounts are more than 10 times higher than those used for flavoring or found in foods and would not be possible to replicate in a meal for human consumption.

The Truth about MSG

MSG is obtained by the fermentation of carbohydrates with a nitrogen source, using bacterial or yeast species from genera such as Brevibacterium, Arthrobacter, Microbacterium, Micrococcus and Corynebacterium. Yields of 100 g/litre can be prepared in this way.

From 1909 to the mid-1960s, MSG was prepared by the hydrolysis of wheat gluten, which is roughly 25% glutamic acid.

Until the mid-1970s, direct chemical synthesis from acrylonitrile was used until the fermentation method was developed, lowering production costs and environmental load.

Like the sodium salts of other amino acids, MSG is a stable colourless solid that is degraded by strong oxidizing agents. It exists as a pair of mirror image stereoisomers (enantiomers), but only the naturally occurring L-glutamate form is used as a flavour enhancer.

Monosodium Glutamate is found in many types of foods, especially fast food restaurants. It has been reported that some of the highest amounts of MSG is found at KFC restaurants.

MSG can also be found in quick meals such as canned soups,
luncheon meats, frozen dinners, and noodles with flavor packets. Many spices contain MSG as well such as dip mixes, taco mixes, gravy mixes, seasoning salts, meat tenderizer and bouillon cubes.

MSG is often found in
Worcestershire sauce, soy sauce, salad dressings, canned gravy and fish sauce.

Many snack foods contain monosodium glutamate as well such as flavored jerky, flavored potato chips (crisps) and flavored tortilla chips. Doritos and Cheetos have been found to contain very high amounts of MSG.

Some infant formulas may contain MSG as well.

Monosodium glutamate has more than one name which can make it quite difficult to track down when reading the ingredients from packaging. If you see
glutamic acid, yeast extract, sodium caseinate, textured protein or hydrolyzed protein on the label, then you can be sure that this particular food contains monosodium glutamate.

While certain food industries and scientific studies claim that MSG causes no significant side effects, the following side effects have been reported by numerous people who have consumed MSG:

  • Headaches that are referred to as MSG headaches.
  • Nausea and vomiting.
  • Diarrhea.
  • Irritable bowel symptoms.
  • Bloating.
  • Stomach cramps.
  • Chest pain.
  • Rashes or hives.
  • Runny nose or sneezing.
  • Weakness and fatigue or lethargy.
  • Warmth on the face, back or arms.
  • Tightness or pressure on face.
  • Pressure around eyes.
  • Burning or tingling sensations in the neck, chest and back.
  • Heart palpitations and rapid heartbeat.
  • Stiffness.
  • Mental confusion, anxiety, mood swings or depression.
  • Difficulty focusing.
  • Dizziness or light-headedness.
  • Blurred vision.
  • Bags under the eyes.
  • Difficulty sleeping and insomnia.
  • Frequent urination.
  • Constant cravings.
  • Restlessness.
  • Extreme drop or rise in blood pressure.
  • Increased rates of obesity.
  • Hypoglycemia.
  • Rectal bleeding.
  • Panic attacks.
  • Behavioral problems and hyperactivity in children that are often attributed to junk foods.
  • Asthma and inability to breathe in asthmatic patients.
  • Swelling on prostate and vagina.
  • Paralysis.
  • Seizures.
  • Brain cell death and brain damage.
  • Brain tumors.
  • Strokes.
  • Severe depression.
  • Rage reactions.
  • Liver abnormalities.

Please consult your doctor or other health care professional if you have any concerns about monosodium glutamate (MSG).