A bigger, better version of this article was posted on September 16, 2014, complete with more research and clearer explanations. Click here to go there: MSG: A Complete Guide to Health and Nutrition.

Monosodium glutamate, aka MSG: a mysterious ingredient maligned by many, understood by few. Described as “the essence of flavor” by some Asian cultures, it’s highly revered for adding that special something to recipes and processed foods.

Why is MSG so pervasive? It’s delicious, it’s inexpensive, and its taste is almost impossible to duplicate. Why is it so disliked by its critics? Well, some people believe it makes them sick. The most common complaint is “Chinese Restaurant Syndrome” – headaches and other temporary symptoms after eating a meal containing MSG. But this only affects those who have a pre-existing sensitivity to MSG, a small percentage of the population. More extreme critics even think that MSG may be linked to diseases like Alzheimer’s and Parkinson’s, but so far studies have not established a link between those conditions and MSG consumption.

There’s a lot more to the story about MSG and the controversy surrounding it. Let’s start at the beginning:

What is MSG?

MSG origins.

Over a hundred years ago, people thought there were only four “tastes,” or special types of flavors that send an electrical signal to the brain: sweet, sour, salty and bitter. But for centuries, the Japanese have used a type of seaweed called kombu to create a rich and deeply savory broth whose flavor was highly valued but couldn’t be described by the traditional four tastes. Japanese scientist Kikunae Ikeda hypothesized that there was something in the kombu that provided a fifth taste—one that had not yet been discovered. In 1909, he succeeded in isolating its source: glutamate, a naturally occurring amino acid1. He called the taste umami, which roughly translates to delicious, or savory. Ikeda’s discovery was monumental because it expanded the number of known tastes to five: sweet, sour, salty, bitter and savory (umami).

Ikeda also discovered that combining glutamate with sodium created a pleasant tasting crystalline powder that was easy to store and use: monosodium glutamate, or MSG (MSG crystals can be seen in the photo at the top of the page). The very next year, MSG was available for sale commercially, and its popularity exploded over the following decades.

MSG in food.

MSG is often termed a “flavor enhancer” because its flavor alone is subtle. In fact, some people can’t even detect it. When added to food, MSG improves the overall flavor of a dish by altering the way we perceive the other flavors which are already present in it. It adds depth and power, smoothes and equalizes unbalanced flavors, and lengthens the flavor sensation so you enjoy a pleasant and lingering aftertaste. This feature is particularly valued in the snack food industry, where the lingering flavor of the seasoning keeps you coming back for more. Seaweed, shiitake mushrooms, cheese, sun-dried tomatoes, soy, meats, wheat, and dairy are naturally high in glutamate, which gives them their rich, deep, and long-lasting flavor.

How to tell if your food contains MSG.

This can actually be difficult, since MSG has little flavor of its own. When I taste MSG in food, it’s not usually its flavor that gives it away, but its “mouthfeel”. MSG creates a unique sensation of almost instantaneous mouth-watering. Once you learn to identify this sensation as MSG, you won’t be able to miss it. If you suspect MSG in your food but you’re not sure, pause after a bite to assess the aftertaste. Is your mouth continuing to water? Does the aftertaste linger for an unusually long time (sometimes minutes)? If so, you might be eating MSG! If you’re eating pre-packaged food, check the label to see if you’re right. MSG has to be labeled as monosodium glutamate – it can’t be hidden as “natural and artificial flavors” or “spices”. Remember that foods that are naturally high in glutamate (with no MSG added) can have these same taste qualities. Chew on some sun-dried tomatoes and you’ll recognize a lot of the sensations and flavors I mentioned above.

If you’re serious about learning how to recognize MSG, buy a bottle from your supermarket. The brand most commonly available in North America is Accent, but you can also find it in Asian markets labeled as MSG. Remember that everyone perceives MSG slightly differently, and some people lack the taste receptors for it altogether, so try it out with a group of friends, and compare your thoughts!

MSG alternatives in food.

Backlash from consumers and grocery stores like Whole Foods and Trader Joe’s have led food companies to search for alternatives to MSG. Autolyzed yeast extract and hydrolyzed corn (or wheat) protein are the most commonly used alternatives because they contain high levels of glutamate. They provide some umami taste, but they bring along a complex mix of other flavors, which isn’t always desirable. They’re also much more expensive than MSG. Where MSG may cost $2 or $3 per pound, autolyzed yeast extract may cost $8 or $9 per pound. On a commercial scale, that adds up fast. To boot, consumers and some grocery stores have started thinking of these alternatives as “MSG-like” and have stopped carrying products that contain them too! The increasing demand for alternatives to MSG, autolyzed yeast extract, and hydrolyzed corn (or wheat) protein keeps food scientists searching for better ways to remove these ingredients without compromising the great flavor their customers expect. It’s a work in progress!

Glutamate in people.

The amino acid glutamate is naturally occurring and abundant in the human body. Its main purpose is to relay signals in the brain. It also helps by bringing potassium to the brain on its way in, and removing toxic ammonia from the brain on its way out. Glutamate is a non-essential amino acid, meaning you don’t need to eat any because the body can make it on its own. Glutamate can be used by the body in a variety of ways: it can be broken down and used as energy; it can be used as a component of larger proteins; it can be converted to (and from) glutamine, a structurally similar but functionally different amino acid; and lastly it can be used in the body as-is to relay brain signals.

Is MSG harmful?

Critics claim it causes various side effects discussed below. Remember, the active ingredient is glutamate, so any side effects that MSG does cause would also be caused by eating other glutamate rich foods.

Claim: MSG causes “Chinese Restaurant Syndrome” (CRS). Symptoms may include temporary headache, nausea, dizziness and tongue numbness after eating.

Answer: Yes, but only in rare cases.

Explanation: In most studies where MSG was served with food, people who were served a placebo complained of as many symptoms as those who had actually consumed MSG – MSG had no effect. However, in one extreme study where individuals were served 10 times the average serving of MSG without any food, some did exhibit symptoms of CRS. Experts generally agree that a small percentage of people have a sensitivity to MSG. If you are sensitive, you probably know it already. But because most people can eat MSG with no issues, the FDA considers it to be “generally recognized as safe” (GRAS) , on a list with salt, sugar, and others. If you’re surprised the FDA still considers MSG safe, consider this: some people are lactose intolerant, but that doesn’t mean the FDA should ban lactose, right? The same goes for MSG. Learn more about the FDA’s GRAS list.

Claim: MSG causes asthma to develop.

Answer: No.

Explanation: Studies show no correlation between the consumption of MSG and the development of asthma. However, in some cases MSG did aggravate symptoms in those with severe, poorly controlled pre-existing asthma. If you have severe, poorly controlled asthma, avoid MSG and other sources of glutamate. If you are asthma-free, you have no need to worry.

Claim: MSG can cause or worsen degenerative brain conditions like Alzheimer’s and Parkinson’s.

Answer: Probably not.

Explanation: Many degenerative brain diseases like Alzheimer’s, Parkinson’s, Huntington’s, multiple sclerosis, and amyotrophic lateral sclerosis (ALS) are associated with elevated glutamate levels. While a certain amount of glutamate is important for healthy brain function, too much glutamate can kill brain cells. Brain cell death causes degeneration (worsening of symptoms) over time in these conditions. However, this doesn’t mean that the MSG (or other source of glutamate) in your dinner was the cause of the problem. There are a number of ways that the normal balance of glutamate in the brain could be thrown off, even if you’re not eating any glutamate at all! So far, there are no studies that support the claim that eating MSG (or other sources of glutamate) can cause or worsen these conditions.

The good news for sufferers is that some research has shown that glutamate-blocking pharmaceuticals can help reduce symptoms and slow degeneration in some Parkinson’s patients. The next step would be more research to find out if a change in diet could help reduce glutamate levels in the first place. Just remember that the body produces its own glutamate in fairly large amounts, so even if you stop eating it, glutamate levels may not fall at all. We can’t be sure until there’s more research.

If you have one of these conditions, I recommend avoiding MSG. It may not help, but it certainly won’t hurt, and these days MSG isn’t difficult to avoid. You may want to talk to your doctor about reducing other sources of glutamate in your diet as well, just in case.

Conclusion.

So is MSG safe or not? The bottom line is yes; it’s perfectly safe for almost everyone. However, some people with MSG sensitivity or pre-existing illnesses might benefit from avoiding MSG and other sources of glutamate.

If you want to avoid eating MSG, here are some tips: When eating out, let them know you need your food without MSG. Be particularly wary of cheese sauces, condiments, gravies, soups, seasoned snacks and Asian cuisine, as these can often contain MSG. Always check the ingredient list on pre-packaged food and look for “monosodium glutamate”. You may want to avoid “[autolyzed] yeast extract” and “hydrolyzed corn (or wheat or other vegetable) protein” too. Removing MSG from your diet can’t hurt you, but if you’re thinking about taking more drastic steps to avoid glutamate in your diet, you should talk to your doctor first.

Footnote.

1Technically, the “true” amino acid in question is glutamic acid. Glutamate is actually an ion of glutamic acid (it’s missing one hydrogen). Because glutamate is less acidic than glutamic acid, it’s better able to participate in bodily functions. Most of the glutamic acid found in the body and in food is actually in the form of glutamate. The terms glutamate and glutamic acid are often used interchangeably, even though they are slightly different.

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