MSG: Separating Fact from Fiction

What is monosodium glutamate?

Monosodium glutamate or MSG is a food additive. MSG is a salt of glutamic acid, which is an abundant amino acid in nature. The human body produces glutamate, so it is a non-essential amino acid that has a number of functions in the body. Glutamate gives a unique taste in food. This taste is called as umami, which is considered as the fifth basic taste.

Glutamate is naturally found in protein-rich foods, such as milk, meat, poultry, seafood, and vegetables. It has also been traditionally used to give an umami taste to food. Often used in Chinese cooking, the symptoms include palpitations, headaches, weakness, and numbness. The usual range of glutamate used in food is around 0.1-0.8 percent. Seek medical advice from a healthcare provider or dietitian if you think you are sensitive to MSG. 

Monosodium glutamate provides a savory, broth-like, meaty taste, or the umami taste when it is used as a flavor enhancer. MSG is classified as a food additive and is typically added to processed and savory foods. It is also used as a tabletop seasoning in certain countries. 

In the past, MSG was naturally extracted from seaweeds. Today, MSG is made through a fermentation process. About one-third of table salt is used in MSG. This combination helps reduce the total sodium content in recipes by 20-40 percent while maintaining their flavor. The metabolism of monosodium glutamate in children and adults is the same. Human breast milk even has 10 times more glutamate when compared with cow's milk. 

Studies have also shown a link between the use of monosodium glutamate and obesity or weight gain. It was also found out that MSG acts as an excitotoxin, which worsens learning disabilities and brain cell damage. According to studies, the moderate use of MSG is safe but may become harmful when it is excessively used. 

History

In 1908, a Japanese chemist named Kikunae Ikeda first identified this flavor enhancer. He discovered that soups made from seaweeds had high levels of this substance, which is different from the basic tastes, such as sweet, sour, salty, and bitter. MSG has a unique taste that tends to enhance the flavor of vegetables, seafood, poultry, and meat. Because of Ikeda’s discovery, MSG from seaweed was commercially produced. Now, MSG is produced through the process of bacterial fermentation using molasses or starch as its carbon source and ammonium salts for its nitrogen source. 

Ikeda also wanted to determine what was responsible for the umami taste. He studied the taste of ammonium, glutamate, calcium, magnesium, and potassium. He found that sodium glutamate was easy to crystallize, palatable, and soluble. He named the product as monosodium glutamate. MSG was commercially produced by Suzuki Pharmaceutical Company, which is now Ajinomoto Co., Inc. MSG is composed of 78 percent glutamate, 12 percent sodium, and 10 percent water. The forms of glutamic acid present are D-glutamic acid and L-glutamic acid. 

Occurrence and Production

Monosodium glutamate naturally occurs in many foods and can be added to certain foods as a flavor enhancer. The food becomes more savory along with enhancing the food's original taste. Earlier, it was prepared by hydrolyzing natural protein, but now, it is made by bacterial fermentation. 

First, a liquid medium is made containing the fermentation substrate, which consists of sugar, molasses, or starch. In the medium, bacteria called Cornyebacterium glutamicus is made to grow. Bacteria grow in the medium and produces glutamic acid. Later, the accumulated glutamic acid is filtered and purified and then converted into monosodium glutamate by neutralization. The white powder of this glutamate is obtained by additional purification, crystallization, and drying. This white powder is then used as a flavor enhancer.

Side Effects of MSG

It was published in reports that if asthmatic subjects consumed food containing MSG, they could suffer from asthma attacks. Further research was carried out, but no significant link was found between the two. It was also found that people who were believed to be monosodium glutamate-intolerant would actually not react to monosodium glutamate but would react with other compounds in the food.

People who complained about headaches, dizziness, and neurological problems were put on similar trials. It was found that these effects were due to inadequate moisture and an increased level of sodium in the body. There was no clear association found between these symptoms and intake of MSG.

Many experiments were also carried out to assess the effects of monosodium glutamate on health. These experiments concluded that as a food ingredient, MSG was generally safe. No adverse reactions were found by the intake of monosodium glutamate by epidemiological studies.

Some experiments showed that subjective symptoms in people would occur if large doses of monosodium glutamate were taken without food. However, these symptoms were rare and reactions would not occur if the substance was given with food. These symptoms were also not persistent or serious. Thus, it can be concluded that for the general population, the intake of MSG is safe. However, food with added MSG can be avoided by those who prefer not to consume MSG.

Salt vs. MSG

Sodium chloride, from a culinary perspective, has its desirable properties, such as enhancing the positive sensory attributes of food. However, since the excessive intake of sodium is linked to an increased risk of cardiovascular disease, stroke, and hypertension, the intake of sodium in the diet must be controlled.

The problem is that less salt or without it, food may become less appealing. Other possible strategies are using salt substitutes such as other ingredients that have other flavors. One food enhancer that can replace salt in food is MSG. However, MSG is also a sodium-containing compound. The amount of sodium present in table salt is 39 percent, while it is only 12 percent in MSG. MSG can add a salty taste to foods and provide an umami taste. Studies have shown that when salt is substituted by MSG in soups, the overall sodium level is lowered while maintaining the palatability of food.

Labelling of MSG

Consumers can make informed choices by reading food labels on prepacked foods. Consumers can check the list of ingredients along with their specific name, identification number, and functional class. The identification number of monosodium glutamate is E621. 

MSG is naturally occurring in hydrolyzed vegetable proteins (HVP), yeast extract, and autolyzed yeast glutamic acid. Upon checking the ingredient list, you will know what glutamate-containing ingredients are present in the food. To make sure that the information on the label is not misleading and is accurate, local regulation is needed in food trade. A "No MSG" claim should not be made if MSG is naturally occurring or is added in the food. 

US FDA's Statement on MSG

Over the years, the FDA has received many reports about common MSG reactions, such as headaches and nausea. However, these MSG side effects were never scientifically confirmed. According to the FDA, MSG is safe when it is eaten at customary levels. However, a subgroup of otherwise-healthy individuals may develop symptoms when they are exposed to 3 grams of MSG without food. The side effects of MSG have not been clearly established because of anecdotal symptoms.