Monosodium Glutamate

What is monosodium glutamate (MSG)?

The sodium salt of the non-essential amino acid glutamic acid. There are 2 types of MSG: the naturally-occurring type and the kind used to enhance the flavor of food.

What is it used for?

Most commonly used as a flavor enhancer.

What are other names for MSG?

What does the FDA says about the safety of MSG?

The FDA classifies MSG that is added to food as Generally Recognized As Safe (GRAS). They report that despite individuals stating they have sensitivity to MSG, scientists testing such individuals with MSG or placebo have inconsistently been able to show that adverse reactions are linked to MSG.

What is Chinese Restaurant Syndrome?

First described by Kwok in 1968. Popular belief states that MSG consumed from eating food at a Chinese restaurant is the cause of adverse effects such as headache or numbness and tingling around the mouth. An orderly review by Obayashi and Nagamura assessing the chance relationship between MSG and headache was inconclusive and suggested that more studies need to be done. Still, eating/drinking MSG in large quantities in soups or without solid food was tied to a higher incidence of headache and other adverse effects.

What is "Umami"?

Discovered by Kikunae Ikeda from Japan in 1907 as the "fifth taste" after sweetness, sourness, saltiness, and bitterness. Umami's existence was challenged among academicians until glutamic acid receptors were discovered in the sensory cells in taste buds on the surface of the tongue. Today Umami has evolved into an internationally-recognized word. Monosodium L-glutamate - the "identity" of Umami is commonly found in the flavor enhancer "Ajinomoto" which is used in many households in Japan.

How is MSG made?

Professor Ikeda was the first to extract MSG from seaweed broth. He removed the liquid used to simmer 38 kg of dried kelp and ultimately succeeded in extracting 30 mg of monosodium L-glutamate. He filed a patent to make MSG and since 1908 it has been commercially made and available. Today MSG is made by fermenting starch, sugar beets, sugar cane or molasses - a process comparable to vinegar, wine, and yogurt making.

Are MSG and glutamate metabolized the same way?

The FDA states that glutamate in MSG and glutamate in food protein are chemically indistinguishable and the body metabolizes both types in the same manner.

What is the effect of glutamate on the body?

The stomach has many glutamate receptors and MSG and other types of glutamate are absorbed via these receptors. As soon as glutamate enters the stomach, it is metabolized for use as energy or integrated into other molecules. Glutamate is also an excitatory neurotransmitter in the brain. Still, glutamate from the diet is thought to be unable to penetrate the blood-brain barrier. However, studies done on mice show that some glutamate penetrated into the brain during the post-natal period and caused neurodegenerative damage.

What does current scientific research say about MSG?

A study published in 2017 examined the effect of high exposure to MSG on fruit flies. Male and female fruit flies 1-3 days old were fed a diet containing 0.1, 0.5, and 2.5 g/kg of MSG for 5 days to analyze antioxidant and oxidative stress markers. Other mice fed MSG for their entire life were tested for longevity. The results showed that those flies exposed for 5 days induced an adaptive response, while those flies with continuous exposure to MSG had up to a 23% reduction in their lifespan. Another study published in 2017 examined the endocrine disrupting potential of MSG on the secretion of the glucagon-like peptide-1 (GLP-1) gut hormone and GLP-1 receptor interaction in humans. Scientists hypothesized that MSG causes obesity based on epidemiological evidence showing a positive correlation between consumption of MSG and increased body mass index as well as an increased prevalence of metabolic syndrome. After 3 hours of exposure of the enteroendocrine cell line to dietary MSG, there was a rise in GLP-1 secretion, while after 72 hours of exposure resulted in "pre-lethal cytotoxicity" and a decrease in secretion of GLP-1. The conclusion of their research suggested that the pathogenesis of MSG leading to obesity may be explained by the impairment of GPL-1 secretion and accompanying satiety responses as well as glucose-stimulated insulin release.

How much MSG does the average individual consume?

The FDA reports that adults consume approximately 13 grams of glutamate from food and about 0.55 grams of glutamate from MSG per day.

What does the FDA require regarding the labeling of MSG?

The FDA requires food labels to write "monosodium glutamate" if the item contains added MSG. The FDA does not require foods such as tomatoes, cheeses, or food containing naturally occurring MSG to be labeled as containing naturally occurring MSG; however such food items cannot be labeled "no MSG" or "no MSG added." In addition, MSG cannot be labeled under "spices and flavoring."

How does the FDA respond to individuals experiencing adverse effects from MSG?

After receiving multiple reports from individuals experiencing adverse effects after consuming foods containing MSG, the FDA decided to ask an independent scientific group - The Federation of American Societies for Experimental Biology (FASEB) to test the safety of MSG in the 1990s. In the end, the FASEB determined that MSG was overall safe. However, their research showed that some sensitive individuals experienced short-term, temporary effects such as drowsiness, flushing, headaches, numbness, palpitations, and tingling when they consumed ≥3 grams of MSG without food.  The FDA is unconcerned about MSG causing serious problems because they report a usual serving of MSG added to food is 0.5 grams and consuming >3 grams of MSG without food was very unlikely.

What foods contain naturally-occurring MSG?

autolyzed yeast
beef
carrots
chicken
eggs
hydrolyzed vegetable protein
hydrolyzed yeast
kelp
mushrooms
parmesan cheese
peas
pork
protein extract
protein isolate
seaweed
soy extract
soy sauce
soy protein
tomatoes
walnuts
yeast extract

What foods contain the additive MSG?

Campbell's Chicken Noodle Soup
Cold Cut Sandwiches
Cheetos
Chick-Fil-A Chicken Sandwich
Doritos
Flavored Pringles
Gravy
Hidden Valley Ranch Dressing
KFC Fried Chicken
Knorr Chicken and Beef Bouillon
Lipton Onion Soup Mix
Pepperoni
Popcorn
Processed food*
Proteins Powders
Seaweed Salad

*check labels

Is MSG the root cause of adverse food reactions in some individuals or is it something else?

In the modern food world, where food is highly processed, the question still remains to be answered. More importantly, if you discover yourself having adverse effects after consuming food you know contains MSG, make sure you take note and avoid these types of foods to prevent a more serious reaction from occurring.

References:
https://chem.nlm.nih.gov/chemidplus/rn/6106-04-3
https://pubchem.ncbi.nlm.nih.gov/compound/23676143#section=Depositor-Supplied-Synonyms
https://www.fda.gov/Food/IngredientsPackagingLabeling/FoodAdditivesIngredients/ucm328728.htm
http://www.foxnews.com/food-drink/2014/11/12/foods-didnt-know-contain-msg.html
https://www.medicalnewstoday.com/articles/318589.phphttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136011/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5278591/
https://www.ncbi.nlm.nih.gov/pubmed/27890806
https://www.ncbi.nlm.nih.gov/pubmed/28087338
https://www.ncbi.nlm.nih.gov/pubmed/28303588http://www.s.u-tokyo.ac.jp/en/research/alumni/ikeda.html
https://www.thedailymeal.com/eat/foods-you-didnt-know-contain-msg/slide-10