So if you remember in the last post we talked about the basic tastes, one of which was umami or “savory” which can best be described as the tastes of good ol’ monosodium glutamate (MSG).

Today, MSG is a flavor enhancer that can often be found in Chinese-style cooking and also a storm of controversy. Just a quick Internet search on MSG can garner stories from people suffering headaches, brain damage, and death – all attributed to MSG.

One of the more popular “attacks” on the substance is that people are attributing it to “Chinese Restaurant Syndrome.” In this syndrome, a person experiences headaches, heart palpitations, an increase in their asthma symptoms, and chest pain.

The “discovery” of this syndrome actually began in 1968, where the term was coined by Dr. Robert Ho Man Kwok in a letter to the New England Journal of Medicine. Though a Chinese immigrant himself, he said he only ever felt the syndrome when he was eating Chinese food in America, and described a number of the symptoms listed above along with the distinct ingredients in the foods he was eating, one of them being monosodium glutamate, The journal became flooded with responses of readers sharing their own stories, and it was even picked up by The New York Times. A study was done in 1969 that injected large amounts of MSG in mice that ignited a firestorm of fear and panic because of the neurological effects on the mice.

 After that point, countless studies have been done on the effects of MSG. It’s been given to patients orally and intravenously, in small does and extremely high doses, to mice and humans, etc.

But let’s take a step back to figure out what we know. Monosodium glutamate is a derivative of glutamate, which we learned is an important neurotransmitter in the body. It’s an excitatory transmitter, which means its presence will cause an increase in the frequency of its nerve impulse when its being sent. Therefore an increase in heart rate wouldn’t be surprising as a potential side effect of MSG.

A lot of studies have reported that headaches increase with the consumption of MSG. A study done in 2009 by Jennifer Xiong showed that neural damage in the brain was dose dependent for MSG, meaning the higher the dose given, the more damage there was to the mature neurons. Though Xiong did not find the exact mechanism, this is what was determined to be the cause of the headaches. However, it was also found that MSG did not cause damage to glial cells or immature neurons, and the presence of Vitamin C also helped decrease the headache effects of MSG.

An important thing to consider hear is the blood brain barrier, which has a low permeability to MSG. This is especially true to dietary MSG (foods naturally present with MSG, like tomatoes, vs. just being added in), so the actual amount of extra glutamate getting into your brain is small. Another thing to consider here is the actual amount of MSG an average person consumes in a day. The average dose for a person in the U.S is 0.55 g/day, but a large meal at a Chinese restaurant could have up to 3 grams, making the possibility of headaches and other symptoms more likely.

So what’s the verdict? Based on numerous studies, evidence of MSG sensitivity is a proven concept. Though the extent of symptoms is based on the sensitivity of the person, it takes a relatively large amount for effects to be felt. So, MSG is regarded as safe in regular amounts, but could have unpleasant when eaten in excessive amounts.

There is so much data on this topic, so it’s easy to see why people are very adamant about MSG. In one single article I read it listed various symptoms of “Chinese Restaurant Syndrome” and then gave links to studies where it was both proven and disproven for every symptom.