I got one of those email-circulated nutrition myths the other day. This one was not about aspartame or margarine, it was MSG (monosodium glutamate), and as usual, it was full of misinformation. This email suggested MSG is in everything we eat, and is responsible for everything from headaches to the obesity epidemic.
Yes, MSG is everywhere. It is often listed as “hydrolyzed vegetable protein” or any other number of names on ingredient labels, which can be confusing. Is it possible that some people experience stomach issues, headaches or other reactions to MSG? Sure. MSG can it cause some mild to moderate reactions for people with an MSG intolerance, but is MSG the route of all these huge health issues? Likely not.
What is MSG?
MSG is a sodium salt from a naturally occurring amino acid, glutamate, that is used as a flavour enhancer. MSG used to be derived from seaweed extract or wheat gluten, but is now usually made using bacterial fermentation of carbohydrates (similar to how beer and wine are made). Commercial MSG is made from fermentation of starch, sugar beets, sugar cane or molasses. In water, it dissociates into sodium (a natural salt) and glutamate (an amino acid that is made in our bodies). Most foods with MSG are foods we should stay away from anyway. MSG is found most abundantly in packaged and fast foods that contain many other additives and less healthy ingredients than MSG.
The studies quoted in the email were all done in rats. When it comes to studies, we have a rating system for determining how relevant they are, and animal studies are very low on the list and don’t hold much weight. Studies with animals, especially rats, are never able to be directly extrapolated to humans. We are very different species with different metabolism processes. What happens to a rat when given a certain substance does not mean it causes the same effect in humans. It’s only a preliminary study.
Secondly, one would have to read these studies in depth to find out 1) if the study design is valid, and 2) what dose were the rats given? The amount of MSG needed to add flavour to our foods is extremely minimal. The rats in these studies are often given mega-doses that humans would never even come close to taking in, even if we drank nothing but soup, salad dressing and gravy all day.
Health Canada states that the safety of MSG has been reviewed by regulatory bodies and food scientists worldwide, and does not pose a health risk to consumers. The FDA concluded in 1995 that MSG is safe for most people when eaten in customary amounts. Food scientist, Harold McGee states that after many studies “toxicologists have concluded that MSG is a harmless ingredient for most people, even in large amounts”. In addition, Health Canada states there is no evidence to support that MSG is related to obesity. For the few small studies that found that high MSG intake may be associated to a higher Body Mass Index, I would dare to argue that the results are not be due to MSG, but rather the fact that people eating higher amounts of MSG also likely have a higher intake of packaged and fast foods, and therefore, also Calories and fat.
Even without MSG added in foods, we are regularly exposed to glutamates which occur naturally in food. In fact, glutamate makes up 10-25% of our protein sources. Interestingly, people with sensitivities to glutamates in MSG have been found to be sensitive to both those from MSG, and those naturally occurring in foods.