MSG is Fine For Your Health

Why you can basically eat as much MSG as you want to without any ill effects.

Pictured: Contains MSG. Surprised? Read on… Photo by Paul Hermann on Unsplash

Monosodium Glutamate, or MSG, is a fascinating chemical. Glutamic acid, the key component of MSG, was first isolated in the early 1900s by a Japanese chemist called Ikeda Kikunae who extracted it from seaweed stock. Kikunae used the term umami - a colloquialism that means delicious - to describe the flavor of the chemical, which has a unique savory taste. After a range of experiments, Kikunae found that MSG was the most stable and commercializable form of glutamic acid, and it soon became an incredibly popular addition to Japanese and other Asian dishes.

MSG is, however, also very controversial. There is a common belief that the chemical is bad for you, with people online arguing that everything from headaches and nausea to cardiovascular disease can be caused by eating even quite small amounts of the stuff. When I posted recently on Threads about MSG, I was surprised to see hundreds of responses arguing that it is a very dangerous chemical that can make people sick.

What’s odd about this is that it’s completely untrue. MSG is one of the safest things you can eat. There’s no evidence whatsoever that eating MSG is bad for your health, even if you believe that you have a sensitivity to the substance.

Let’s look at the science.

Tenuous Theories

The first important thing to understand is what MSG actually is. The compound is made of two main components - sodium, and glutamate or glutamic acid. Sodium, of course, is the metal ion that’s present in salt. Too much can be bad for your health, but you need some sodium to stay alive.

Glutamate is a non-essential amino acid. If you remember your high school science, amino acids are the building blocks of proteins which make up quite a lot of, well, us. Here, non-essential means that you don’t have to eat the substance - your body can make glutamate without you eating it. So MSG breaks down in the body into two substances that you need to live, which is not the strongest starting point for a poison that can cause you serious pain.

It’s also worth noting that glutamate is everywhere. Red meat naturally contains the compound. Milk has it too. Obviously, some seaweeds have pretty concentrated amounts. Peas and potatoes are quite high in glutamate, and aged cheeses like parmesan often have higher levels than products where humans have added MSG intentionally.

Pictured: Chock full of glutamate. Photo by Aliona Gumeniuk on Unsplash

So from a theoretical perspective, the idea that MSG is harmful is a bit thin. Most of the suggestions that you can be directly harmed by the chemical come from basic science where researchers give mice and rats the substance. In these studies, researchers have indeed found everything from fertility issues to metabolic dysfunction caused by giving rodents doses of MSG.

The problem with these studies is that the amount of MSG that lab rats get is drastically higher than the amount humans could ever hope to ingest. For example, this review of the impacts of oral ingestion of MSG in rodents found that the lowest amount that was associated with any harm was 1 gram per kilogram of body weight per day.

Most human food - even the stuff with added MSG - has pretty low levels of the stuff, but if we took something like a can of processed soup it might have up to 5 grams of MSG per kilo of soup. To get a dose of 1 gram per kilogram of body weight, your average adult human would have to drink 25-30 litres of soup per day for years at a time.

Pictured: Soup. It’s also worth noting that 5g/kg is a VERY high amount even for canned soups. Most have more like 1/5th of that, and brands like Campbell’s have now produced many soups with no added MSG at all. Photo by Calle Macarone on Unsplash

Some of the studies do use lower doses, but these are almost all experiments where MSG was injected rather than ingested. If we commonly shot up MSG it might be an issue, but it’s not clear what some possible toxicity from injected MSG in rodents shows about humans eating foods with very low levels of the compound in them.

So while it’s true that extremely high doses of MSG may cause negative impacts in rodents, it’s not obvious that much smaller doses of the stuff are harmful to actual human beings. In fact, based in part on animal data, food agencies across the world consider MSG (and other glutamates) to be safe for human ingestion at normal doses. The European Union has set a relatively conservative threshold for MSG intake at 30mg/kg per day for humans, which would be about a litre or two of the aforementioned soup.

Chinese Restaurant Syndrome

So the animal evidence shows, at doses we normally see in real food, that MSG is very safe. You’d have to be eating truly heroic amounts of food with incredibly high levels of the chemical in it to be at any risk at all. If you were eating litres of processed soup a day, you’d probably be in more danger from the salt intake anyway.

But there’s another claim about MSG. Many people believe that eating food which has had MSG added to it can cause people to have acute symptoms like headaches and nausea. This remarkably pervasive idea can mostly be traced back to racism against Chinese immigrants in the US in the 1970s.

The story is quite fascinating. In 1968, a Chinese-American physician* wrote into the prestigious New England Journal of Medicine to briefly note his theory about Chinese Restaurant Syndrome. Chinese Restaurant Syndrome was a condition being reported around the country where people would feel unwell and headachey after going out to eat the staples of Americanized Chinese food.

Pictured: Delicious, but inauthentic. Photo by Janesca on Unsplash

This caused a huge controversy. Newspapers at the time were all too happy to jump on the idea that Chinese immigrants could be making people sick with their food. A series of studies where people were given MSG by American researchers seemed only to confirm that this could indeed be a problem.

Unfortunately, most of these studies were extremely bad. They mostly involved telling people that MSG has been associated with negative health consequences in the past, then giving them MSG and asking how they felt. Most people, in these scenarios, report some ill effects, but it’s impossible to know if it’s the MSG that’s to blame or just the expectations of the participants.

In the decades since, we’ve tested MSG in much more robust ways. What we generally see is basically the same trend - when people are aware that they are getting MSG, they are quite likely to report issues. When they have no idea what they’re getting, the issues disappear. Take this recent systematic review of human studies looking at headaches. These are experiments where people were either given MSG or a placebo alternative. When the MSG was dissolved in a drink and compared to a placebo with no MSG, most people both noticed the difference in flavor and reported side-effects from MSG. When the MSG was incorporated into food, and was no longer easily detectable through taste, people no longer reported the same side-effects.

Even some of the studies were people know they’re eating MSG have inconsistent findings. Here’s a study where men were randomized to either get a low or high MSG drink, or one with salt in it. Compared to the salty drink, low MSG was associated with a much higher rate of headaches, but the higher MSG drink had no increased risk of headaches at all.

There’s also currently no evidence that MSG intake causes asthma to get worse, although the data is pretty slim.

On top of all of this, we have challenge studies for people who claim that they are sensitive to MSG. In these pieces of research, people who say that they have a sensitivity to MSG are either given the chemical or a placebo with food, and then they have to report their symptoms after a period of time.

These experiments have largely failed to confirm the existence of MSG sensitivity. One of the biggest studies took 130 people who claimed to have a sensitivity to MSG and gave them either MSG or a placebo on two separate days. Of these 130 people, 80 either reported no reaction to either scenario or only reported a reaction to the placebo. Of the remaining 50, 11 reported the same reaction to the MSG and the placebo. This left 39 people who said that they had a sensitivity to MSG who actually reported symptoms after eating the stuff.

The study then took these 39 people and checked whether their responses were replicable in further challenges. At the end of the study, there were only 2 (1.5%) people who claimed to have an MSG sensitivity/allergy who could reliably tell when they were given MSG rather than a placebo substance. Even these 2 people had significant differences in their reported responses at different times.

The data suggests that most people who think that they are sensitive to MSG are wrong. It’s possible that there is a very small group of people who think that they are sensitive to the chemical and are correct, but given the evidence we’ve got even that’s not very likely. The most likely explanation is that people sometimes feel sick after eating a range of foods, and inaccurately blame MSG for their symptoms which are really caused by other things.

Eat Your MSG

There’s no good data indicating that MSG is harmful to humans. Even people who believe that they have a sensitivity to MSG generally can’t tell the difference between how they feel when they eat the real chemical or a placebo in appropriately blinded studies.

There are also some vague epidemiological associations between MSG and human health, but those are pretty unconvincing. MSG, of course, makes food taste better, so it’s not unlikely that people who eat a lot of MSG would have higher rates of obesity and other diseases. It’s a bit like finding that higher caloric intake is bad for you - eating a lot of food is a problem for many reasons, of which MSG is the least convincing.

This is reinforced by the fact that MSG really is in everything. Tomatoes. Cheese. Fish. Meat. Milk. There are very few diets you can eat which eliminate MSG from your life. Unless you’re eating boiled rice or plain oatmeal, you’re probably getting a few hundred milligrams of MSG per day.

Personally, my advice is to eat as much MSG as you want within reason. It’s extremely difficult to reach an unsafe intake of MSG, but obviously if you do somehow manage to eat 5+ grams of the stuff a day you might want to cut back. Short of truly heroic amounts of the stuff, MSG is entirely safe to eat, based on current best evidence.

Pictured: My giant bag of MSG. I add it to everything, it’s fantastic on popcorn and on most other savoury things. This is not an endorsement of the brand, it’s just the cheapest one I could find at the local Asian supermarket.

*Note: There is a theory that it was actually a hoax perpetrated by a white man from the US. This American Life has a great investigation into the topic which shows that it almost certainly was a Chinese-American physician who wrote the initial letter, raising what he saw as a legitimate concern with Chinese-American foods.