MSG is a common additive in food that has a full name of monosodium glutamate. It’s a salt of glutamic acid, which is an amino acid commonly found in nature.

Over the years MSG has developed a reputation as a harmful ingredient and you’ll often see foods use “NO MSG” as a selling point for the health benefits of their products.

What’s bad about MSG?

In some studies a causal relationship has been established for the following maladies:

1. Obesity
2. Neurological disorders involving the nervous system like Alzheimer’s and Parkinsons
3. Food cravings and addiction

Let’s take a close look at each of these claims and see where the truth does (and doesn’t lie). But first let’s start with the basics.

What is Glutamate? What is it Used For in the Body?

Like I said before, glutamate is a non-essential amino acid. “Non-essential” means your body can produce the compound on its own, even if it doesn’t receive any glutamate in the diet. Glutamate is very common. It’s found in most proteins, and it’s estimated that the majority of Americans digest between 10g and 14g of glutamate per day, which is more or less okay.

In the body, glutamate is an important signaling molecule that transmits electric signals through the central nervous system. It’s an “excitatory” molecule, and travels through ionic (electrically charged) channels in the body like synapses, signaling molecules, and cellular receptors. Disorders like Parkinson’s and Alzheimer’s are associated with malfunctioning of different signaling molecules in the central nervous system that use glutamate to perform various cellular functions.

Glutamate is also very important for your sense of taste. “Umami” is a flavor that gives a savory sensation, and umami taste buds have glutamate receptors on them.  The umami taste is why MSG is used so frequently in foods, because it  makes food more savory. And it works. Most blind, placebo controlled taste tests show that food with MSG added to it gets higher marks than similar foods without MSG.

What does MSG Have To Do With Glutamate?

For the most part, MSG is glutamate.  Monosodium glutamate is just glutamate with a sodium molecule attached to it. In your stomach those two molecules dissolve and you’re just left with glutamate in your gut. Glutamate that comes from your food, MSG, or other sources all ends up as the same thing in your body.

So most of the health issues surrounding glutamate have to do with the health issues surrounding glutamate intake, and whether too much of it is bad for you.

And too much glutamate is bad for you, but there are a lot of caveats you need to understand to accurately digest the consequences of consuming large amounts of MSG, because they may not apply to you. And at the end of this article I’m going to present the best evidence I know of that contradicts my conclusions to make sure you understand the entire MSG story.

I hate health advocates who tie up their health advice in moral platitudes that take advantage of mood affiliations to heighten their own status. It’s the same tactic health food companies use to deceive ignorant consumers into thinking their scammy products are better for you than they actually are.  I won’t do it.

So, on with the show.

Does MSG Cause Obesity?

A lot of evidence has accumulated over the years that has established a causal link between MSG consumption and adult obesity. Most of these studies have been performed on rats, and there are a lot of them.

How does it work?

It mostly comes down to the fact that MSG is an excitatory molecule, and sometimes too much excitement is a bad thing. Glutamate plays important roles in neurological and lipid hormone regulation, and these two work together to form metabolic “set points” that your body tries to maintain to keep your body weight on an even keel. Too much glutamate can put important signaling molecules in both these systems into overdrive, which then become insensitive to normal stimulation and don’t work as well as they’re intended to. This synaptic burnout causes your body to lower its baselines for thermal regulation, fat metabolism, and energy balance, which puts your body into a long term “fat accumulation” mode that can be hard to break out of.

In fact, in a lot of studies MSG intake causes big holes (called lesions in the literature) where there are supposed to be glutamate receptors that regulate these sorts of systems.

MSG, Obesity, and Child Nutrition

These sorts of dynamics are especially true for MSG consumed early in life.

It’s an accepted fact that nutrition during periods that are developmentally sensitive can significantly affect your body’s “set points” for different sorts of metabolic functions. This is also true of MSG.

For example, a study published in the American Journal of Physiology in September 2011 compared the temperatures, metabolisms, and fat content of groups of newborn rats that were raised identically except one group which was fed with MSG.

After 10 days the group of rats which were fed MSG showed higher body temperatures, lower body masses, and less fat tissues.

One might think this is good, but these indicators are not healthy when you’re an infant. The MSG treated rats had stunted growth, which caused the body to secrete less fat-regulating hormones like Leptin, have lower body temperatures in adulthood, and have a higher tendency to store fat instead of burn it.

This particular study is not unique. It’s now a common practice to feed infant rats with MSG early in life if you need fat adult rats to perform studies on.

MSG and Neurological Disorders Like Alzheimer’s, Parkinsons, and Epilepsy

The spotlight first began to shine on MSG when a paper was published in the journal Science in 1957 by scientists named John Olney and Lawrence Sharpe that found rhesus monkeys injected with glutamate began to form lesions (holes) in their central nervous system and began to suffer from bouts of epilepsy.

Similar to fat regulation, Central Nervous System regulation began to become frayed when glutamate receptors become overactivated, which sets off a cascade   of enzymatic reactions which result in cell death, which leaves big holes in your central nervous system that aren’t supposed to be there. Needless to say, that causes problems, and malfunctioning glutamate receptors have been shown to be a common denominator in a variety of neurological disorders including but not limited to Parkinson’s, Alzheimer’s, Multiple Sclerosis, etc.

So glutamate at high dosages begins to act as a neurotoxin.

MSG and Food Addiction and Cravings

To complete the trifecta of maladies, let’s discuss why MSG is associated with food cravings.

As noted before, glutamate is responsible for the “Umami” taste which your body recognizes as savory. Humans like savory foods, and like other desirable taste sensations, your body releases a bunch of chemicals when you eat it that tells your brain “Get more of this! It’s Really good! Who Knows when you’ll have it again!”

Dieters routinely report liking MSG-enhanced foods more than the same food sans MSG. A study published in the May 1991 issue of Physiology and Behavior found that healthy men fed MSG optimized foods consumed larger portions and desired more MSG enhanced food with each subsequent meal that contained MSG. The savoriness of MSG contributes to that hungry feeling inside you right after you eat a processed snack.

In the 1960’s there was a joke about “Wonton Soup” headache which commonly occurred at cheap chinese restaurants. It turns out the reason for the malady was excessive amounts of MSG added to the food, which caused allergic reactions in some people. MSG is more commonly added to food in Asia than in the America’s and Europe, and cheap chinese restaurants use a lot of MSG to mask the low quality of the ingredients they use.

What Sorts of Food Contains MSG? How Can I Tell?

Just about any processed food can have MSG added to it. It’s inexpensive to manufacture, and is used in just about anything. You have to read the labels. MSG used to be included in the term “Natural Flavors”, before the practice was banned, and now it must be listed individually as an ingredient. It’s commonly found in soups, cheap chinese foods of all varieties, and

Monosodium glutamate is almost always listed towards the middle and end of the ingredients section on foods because the addition of MSG follows the “goldilocks” principle. A little bit of it goes a long way to add a mouth-waterfing feel to food, but too much causes food to taste rancid. It’s recently been discovered that the savoriness of MSG can be enhanced by mixing it with sodium nitride and disodium 5′-guanylate, which reduces the bulk amounts of MSG that need to be added to foods to create the desired taste effect.

MSG sounds like toxic waste. Why on earth is it permitted in food?

Believe it or not, there’s some very good evidence that suggests MSG is harmless. The main points are:

1. Asian populations consume more MSG than americans and europeans, but do not suffer from the same health maladies
2. All MSG gets turned into glutamate, and the total amount of MSG you consume is a fairly small portion of the total glutamate you get in your diet. Most estimates fall between 0.5 and 3 g of MSG per day.
3. The majority of glutamate is metabolized in the gut, and does not enter the rest of your system, even if you eat a lot of it.
4. You can consume a lot of dietary glutamate before anything bad happens. More than most people consume in their diet.
5. Studies done on rats, sheep, pigs, and monkeys don’t always carry over to humans, even if they’re well conducted.

If you want a good overview of the “pro-MSG” view, read this paper: http://www.nature.com/ejcn/journal/v61/n3/full/1602526a.html

It was published in the journal Nature, and it summarizes the consensus reached by the heads of European food regulatory committees on why glutamate should be allowed to be used in food.

You don’t have to be a conspiracy theorist to accept why people would write the things they did. They make a lot of good points, and undoubtedly most of them are true.

However, I still believe MSG is an ingredient that’s best avoided. Even in the paper I cited above, the authors make the following concession:

 Thus, one is aware that virtually no food can be described to which a zero-risk may apply…….Whereas it is still a problem to assess the safety of a complex food, the assessment of a distinct compound that may be employed as a food additive is a well established procedure.

That might not sound like much, but it’s become a common occurrence that small differences in sensitivities to different ingredients have large effects when they’re consumed in large amounts with other weird stuff, and it’s very difficult to know what your natural tolerance to an ingredient is until you have an adverse reaction to it.  50 years ago the presence of allergens wasn’t nearly as noticed as it is today. There wasn’t a point, since allergic levels between people can’t be differentiated at low dosages. When you drink additives from a fire hose even small variations in ingredient sensitivities can have large effects, especially when mixed with other environmental pollutants which can have a multiplying effect on your health outcomes.

Besides, since MSG is such a cheap additive, it’s often found in foods which throw in every weird additive but the kitchen sink, and it’s presence is usually a pretty good indicator for low-quality processed food.

“Eat Plants” is a blunt rule, but it’s effective at eliminating the most egregious dietary mistakes and keeps you on the right track at least 95% of the time.

Is MSG Evil? Should We All Get Angry at Big Ag and Big Food For Maliciously Polluting Our Food?

In these types of articles, you’ll often see closing remarks that frame large food companies and nefarious “industrial complexes” that conspire to keep helpless peasants sick and unhealthy at the expense of profits, and tacit implications that the world would be a much better place if these ingredients and institutions never existed in the first place.

In my opinion, those folks are seriously lacking in originality. Creating boogeymen and casting stones at a vague enemy creates for good storytelling, but misses an incredibly important point:

MSG has had an incredibly positive impact on humanity!

I still try not to eat it, but people frame the issue in the wrong way. Suppose I conducted a survey that asked a random group of people this question:

“If an abundant, naturally occurring ingredient was discovered that helped the body perform a variety of vital functions, made food taste delicious, could be tolerated at high dosages by just about everyone, and manufactured at next to no cost, do you think it’d be alright to add it to food in small amounts?”

My guess is at least 85% of people would say yes. Well, that describes MSG just about perfectly!

The problem with MSG is not the danger of the ingredient itself (for the most part), but the fact that it plays a role in a larger eco-system of food additives which have to be used together to give food certain properties, which add up to create undesirable end-of-point health outcomes which consist of individual components that have non-descript health effects. And more often than not, MSG comes as a package deal with other ingredients which contribute to this effect.

Research Done on the Health Effects of MSG:

“Brain Lesions in an Infant Rhesus Monkey Treated with Monosodium Glutamate.”  John W. Olney and Lawrence G. Sharpe. Science 17 October 1969: 166 (3903), 386-388. [DOI:10.1126/science.166.3903.386]

“Brain Lesions, Obesity, and Other Disturbances in Mice Treated with Monosodium Glutamate”  John W. Olney.  Science 9 May 1969: 164 (3880), 719-721. [DOI:10.1126/science.164.3880.719

Kanarek, et. al. “Juvenile-onset Obesity and Deficits in Caloric Regulation in MSG-treated rats.”  Pharmacology and Biochemical Behavior. May, 1979. Vol. 10 Issue 5, pgs. 717-721.

Maragakis, et. al. “Glutamate Transporters in Neurologic Disease.”  Archives of Neurology. March 2001. Volume 58, pgs. 365-370.

Stanley, Sarah, et. al. “Hormonal Regulation of Food Intake”  Physiological Reviews. October, 2005. Volume 85. pgs. 1131-1158.

Janeczko, Michael, et. al. “Extensive Gut Metabolism Limits the Intestinal Absorption of Excessive Supplementary Dietary Glutamate Loads in Infant Pigs”  The Journal of Nutrition.  November, 2007. Vol. 137, pgs. 2384-2390.

Schoelch, Corinna, et. al. “MSG Lesions Decrease Body Mass of Suckling-Age Rats by Attenuating Circadian Decreases of Energy Expenditure”  American Journal of Physiology. October 2001.

Bursey, Roger, et. al. “A Lack of Epidemiological Evidence to Link Consumption of Monosodium Glutamate and Obesity in China”  American Journal of Clinical Nutrition. September, 2011. Volume 94, pgs. 958-960.

Beyreuther, K, et. al. “Consensus Meeting: Monosodium Glutamate – An Update” Nature. September, 2006. pgs. 304-313.

Pizzi, William, et. al. “Effects of Monosodium Glutamate on Somatic Development, Obesity, and Activity in the Mouse.” November 1976. Volume 5, Issue 5. Pgs 551-557.

Bellisle, F, et. al. “Monosodium Glutamate as a Palatibility Enhancer in the European Diet” Physiology and Behavior. May, 1991. Volume 49, Issue 5. Pgs 869-873.