Monosodium glutamate (MSG) is a flavour enhancer that you’ve likely run across if you’ve ever eaten before. It is found naturally in many foods but it is most famously known as an additive that provides food with a savoury taste. Though MSG has been around since the early twentieth century, in more recent times, its safety has been questioned and it has been built up as a potentially dangerous additive that can cause a whole range of health issues. How much truth is there to that?
Here's everything you need to know about MSG.
What Is MSG?
MSG – monosodium glutamate or simply sodium glutamate – is the sodium salt of glutamic acid. When we say ‘salt’ we’re usually referring to table salt, the chemical compound known as sodium chloride. Sodium glutamate is similar to this compound, but instead of sodium and chloride ions being bound together, MSG has sodium and glutamic acid bound together.
It is considered a flavour enhancer because it is added to a wide range of products to improve the taste, rounding them out by giving them a more 'full' flavour.
The compound was first extracted by a Japanese chemist, Kikunae Ikeda, in 1908. Ikeda had noticed that the addition of kombu - a type of edible kelp - made his dashi broth taste better. So, as a chemist is wont to do, he isolated the crystalline compound from the kombu and found that this glutamate was responsible for giving his broth the meaty, savoury flavour that he enjoyed. Ikeda named this particular taste 'umami'. It is now considered one of the five tastes that you can perceive whenever you eat something, alongside the four other tastes: Salty, sweet, bitter and sour.
Shortly after discovering the compound, Ikeda became the very first MSG salesman, using wheat and defatted soybean to mass-produce the crystalline form of MSG and sell it as the product 'Aji-no-moto' in 1909. Early production utilised a process called hydrolysis, but these days, MSG is manufactured in a similar way to yoghurt and wine - by bacterial fermentation.
Importantly, glutamate is a naturally occuring amino acid and can be found in a wide variety of foods including mushrooms, tomatoes, soy sauce, Vegemite and certain cheeses. It is even found in breast milk at high concentrations. It is also synthesized by the human body and can act as a neurotransmitter, chemical messengers that can communicate information from the brain.
The mass-produced MSG and the glutamate within your body are, chemically, the same thing.
According to the FDA, America's Food and Drug Administration, an adult takes in about 13 grams of glutamate from food per day whereas only 0.55g of MSG is ingested daily. However, in Asia, upwards of 1.5g of MSG may be ingested per day.
Is MSG Bad For You?
The idea that MSG has a range of negative effects began to appear in the late 60s after a letter titled 'Chinese Restaurant Syndrome' by Dr Ho Man Kwok was published in the highly-respected New England Journal of Medicine. This resulted in a flurry of scientific study subjecting a range of species to extremely high levels of MSG and reports of nausea, headaches, weakness and palpitations in a subset of the human population.
The renewed interest in MSG safety stems from the fact that the European Food Safety Authority (EFSA) updated their recommendations in mid 2017, proposing a daily limit of 30mg/kg of body weight per day of MSG and other glutamate-based food additives.
Currently, the peak body for food safety in Australia and New Zealand, Food Standards Australian and New Zealand (FSANZ), considers MSG safe and authorises it as a food additive as long as a food manufacturer only adds MSG to its product up to a certain limit. Their official stance is that the current studies have failed to determine a causal assocation between negative effects and MSG.
They do concede that a subset of the population may experience adverse effects when exposed to a large amount of MSG in the absence of food.
What Does The Research Say About MSG?
A search for 'MSG', 'monosodium glutamate' or simply 'glutamate' returns over 8000 results on the online PubMed database, with journal articles stretching back to 1948.
Among the many purported evils of MSG are its effects as an asthma-inducing agent or a neurotoxic agent, but the research says otherwise.
MSG was linked to asthma in the 1980s, with suggestions that it can induce the bronchorestriction seen in those with the condition. A clinical trial in 1998 of asthma sufferers who perceived themselves as MSG-sensitive found no evidence to suggest this was the case. Mouse models of asthma demonstrated the same. Further to this, a 2012 Cochrane review of the literature found that there was no evidence to support the idea of MSG-induced asthma. However, the team also concluded studies to rule out MSG as a potential contributing factor in younger children remained necessary.
Some evidence suggests that MSG is neurotoxic and that it may cause problems with the kidney in mice and rats. However, some of these earlier conclusions - particularly those related to neurotoxicity - have been drawn from studies in which rodents were injected with MSG at high concentrations. This is fundamentally different to the way in which MSG interacts with the body when encountered naturally. Studies such as these do not adequately replicate the human experience of ingesting MSG. That does not discount these findings but merely states that caution is needed when interpreting their results and applying them to humans.
There also persists a notion that MSG has been produced by using wheat, which contains gluten, and thus gluten may contribute to some of the negative effects that are seen when consuming foods that contain MSG. However, as previously stated, the current method for production of MSG is bacterial fermentation and should not result in wheat or wheat products being present in refined MSG.
It is important to note that MSG from the diet, be it free or artifically added, is always consumed with other foods. This consideration must be made in any controlled trials relating to testing the negative effects of MSG and thus a more individual approach to MSG sensitivities may need to be considered.
How Do I Know If Something Has MSG In It?
The FSANZ standards state that any food product that has MSG added to it must clearly say so on the label. The ingredient list must either state that they contain 'Flavour enhancer (MSG)' or 'Flavour enhancer (621)'. If a product contains Flavour enhancer 622, 623, 624 or 625, then the product contains another glutamate additive.
Where does that leave you in a restaurant? Restaurants are not required to provide any information on MSG as the food products they sell do not generally contain a label. However, if asked, the restaurant should be able to tell you whether or not the flavour enhancer has been added to their product.
Should I Be Worried About MSG?
The acute and chronic effects of MSG have been studied extensively over the last 60 years. There does not exist enough evidence to say that the current level of MSG consumption results in negative health effects in the general population. However, there are a subset of human beings that may experience some discomfort in the period after consuming food products high in MSG. The statement given by the Federation of American Societies for Experimental Biology (FASEB) in 1995 demonstrated that these individuals "may experience adverse reactions such as headaches or nausea if they ingest more than three grams of MSG."
Another study by Geha in 2000 demonstrated that large does of MSG given without food (up to 5g) may cause adverse effects, but that the responses did not differ greatly or consistently enough from placebo controlled groups.
The sheer weight of evidence that has been accumulated over the years, especially those in placebo-controlled, double-blind, randomised trials strongly suggests that there is no cause for concern or reason to critically regulate MSG intake. However, more studies are required to completely understand the effect of high doses of MSG in young children.