Welcome to “chemicals and society”, where we highlight the current understanding of the biological effects and safety of some of the most common chemicals in today’s society.

Today’s Chemical: Monosodium Glutamate (MSG)

What is MSG?

MSG is monosodium glutamate. “Glutamate”is the salt of glutamic acid, which you may remember from biology class as one of the 20 amino acids that make up the proteins in our body. “Monosodium” means there is a single sodium ion associated with each molecule of glutamic acid. Glutamic acid is the 6th most common amino acid in vertebrates – it makes up about 5.8% of the proteins in your body and the meat that you eat. Sodium is also very common in the diet and inside your body. Another sodium salt, Sodium chloride (table salt) is used in cooking throughout the world.

What is MSG used for?

MSG is used as a flavor enhancer, which means that while it doesn’t have a particularly strong taste on it’s own, it brings out the flavors of other foods – particularly meats and savory foods. It is most commonly used in flavor-enhancing meat tenderizers and Chinese cooking, though you’ll find it in many, many prepared foods like chips, snacks, and soups. It’s in Doritos, Kentucky Fried Chicken, most canned soups, processed meats, Chick-Fil-A sandwhiches, Cheetos, Pringles, and ramen noodles. You get the point.

Is MSG safe?

All available scientific data has demonstrated that MSG is safe when consumed in food. Before we get into this data and some of the unfounded claims about the dangers of MSG, let’s take a pause to consider how MSG is handled by the body.

Salts are the result of ionic interactions between a cation (positively charged group, in this case a sodium ion), and an anion (a negatively charged group, in this case glutamic acid). In the case of what we commonly call table salt (sodium chloride) – sodium is again the cation, while chloride is the anion.

This ionic interaction is much weaker than a covalent bond (like the bonds that hold the atoms of glutamic acid together). When a salt is in a solid, crystalline form (like the sodium chloride in your salt shaker, or monosodium glutamate powder), the two ions stay together. However, when dissolved in water, the ions go their separate ways. This is because water has both positively and negatively charged groups – the positively charge hydrogens associate with chloride, while the negatively charged oxygen atoms associate with the sodium. As a result, a glass containing table salt completely dissolved in water does not contain sodium chloride in water – it contains sodium ions and chloride ions in water.

The same is true for monosodium glutamate. Once it is dissolved in water, as it will be when you digest food containing MSG, it is no longer monosodium glutamate. Instead, it is sodium and glutamic acid in water. So what happens to MSG once it is absorbed into the body? That’s a trick question, because MSG is not absorbed into your body – sodium and gluatamic acid are absorbed, and once in your body they will stay separate. No matter how much MSG you eat, your body (outside of your intestines) will only ever be exposed to the individual parts – sodium and glutamic acid.

This should provide us all a considerable amount of comfort, because sodium and glutamic acid are two of the most common molecules in your body already. Certainly, it is possible to consume toxic levels of glutamic acid or sodium (and by extension, MSG), but you’ll have to try very hard. The sodium ion is actually the more toxic molecule – but you’ll have to ingest hundreds of grams of salt very rapidly to cause toxicity, and you will almost certainly throw up trying to do this (please don’t try this). Your body is already about 0.15% sodium and 1% glutamic acid – that’s about 100 grams (3.5 ounces) of sodium and 650 grams (23 ounces) of glutamic acid in an average sized (70 kg) person. It is no stretch to say you are literally made of these chemicals.

It should seem far-fetched to suggest that two of the most common molecules in your body, when consumed together, are somehow toxic despite the fact that these molecules immediately separate once you eat them. It sure seems far fetched to us. Back in the 1980’s and 1990’s MSG was linked to something called “Chinese food syndrome” or “MSG symptom complex,” which was a set of symptoms including headache, skin flushing, sweating, and “general discomfort”. MSG is, in fact a commonly used additive in Chinese (and Japanese) food, however, a series of double-blind clinical trials in the 1990’s failed to show any link between MSG and this “syndrome”. In reality, MSG is used in so many other foods that the suggestion that MSG in Chinese food is uniquely causing these symptoms smacks of racism.

The link between Chinese food syndrome and MSG became so widely suggested that the FDA felt it necessary to address the issue with a statement on MSG safety on their website. Several anti-MSG sites we have seen reference this as “proof” that the FDA believes that MSG is linked to Chinese food syndrome or other adverse health effects. However, the FDA site clearly states that rigorous studies have found no link between MSG and Chinese food syndrome. They go on to say that if you were to eat 3 grams of MSG on an empty stomach, some sensitive people might experience “some short-term, transient, and generally mild symptoms, such as headache, numbness, flushing, tingling, palpitations, and drowsiness”. That is way more than you will ever eat in a meal. And honestly, these symptoms are basically the body’s way of telling you that you are not good at decision making.

Besides Chinese food syndrome, some claim that MSG can cause liver damage, neurological effects, joint pain, and a number of other ailments – there is no data to support any of these claims. Some poorly controlled studies have identified a link between high MSG consumption and obesity or diabetes, but this shouldn’t be a surprise, since heavy consumption of processed foods (which often contain MSG) is linked to these diseases anyway.

What’s the Bottom Line?

Eating large amounts of junk food loaded with food additives is not healthy, not because of the MSG, but because these foods tend to be high in fat, sugar, and calories, while also being low in vitamins, minerals, and fiber. MSG (like GMO foods) is often used as a scapegoat for metabolic diseases like obesity, diabetes, and heart disease. These conditions are caused by diets high in processed foods, fat, and total calories, not by MSG or GMOs. Eating MSG in moderate amounts is perfectly safe. If you are eating large quantities of MSG every day, it’s time to change your diet.