YSN-ASM Science Café
MSG-Phobia: A Consequence of Flawed Science

In this Science Café session, Mr Shawn Keng is joined by ChM Dr Fatimah Salim from UiTM, who will be debunking the oft-misunderstood element of flavouring that enriches our tastebuds: monosodium glutamate (MSG).

Although we generally know MSG as a common flavour enhancer, but what exactly is it? Dr Fatimah introduced MSG to viewers from a scientific standpoint. It is the sodium salt of glutamic acid, which readily dissolves in solution to sodium and glutamic acid.

Known in the culinary world as the fifth basic taste, after sweet, sour, salty and bitter, it lends itself to enhance the natural flavour and palatability of food. Most might know its inclusion in Japanese and Chinese cuisine, but Sabahans are also quite fond of it, according to Dr Fatimah.

Dr Fatimah gave a quick history lesson on how MSG was discovered. A Japanese biochemist named Kikunae Ikeda was attributed to the discovery of this tasty molecule. He was trying to isolate and duplicate the savoury taste of an edible seaweed called kombu, which is a common ingredient used in Japanese soup base. Dr Ikeda found that when glutamate is added to food, it makes the food more savoury and pleasing to the palate. When he developed a process to stabilise pure glutamate using ordinary salt, Dr Ikeda patented the process and began manufacturing MSG in 1909 with the name Ajinomoto, meaning “the essence of taste”.

Next, with the aid of helpful diagrams from the originator of MSG themselves, Dr Fatimah explained how MSG is produced. Starch is extracted from the cassava tubers and corn, as well as sugar from the sugarcane plant in the form of molasses. Exhibiting her love for natural products, Dr Fatimah added a trivia about how molasses gets their brown colouring: it comes from tannins. Tannins are present in the plant, which is usually then filtered to yield the pure white sugar that we use regularly.

Continuing her explanation, the glucose broken down from the starch is then fed to microbes called glutamic acid bacterium. The enzymes within these bacteria ferment the glucose, converting it into glutamic acid. Adding salt (sodium chloride) to the glutamic acid will neutralise the acid, producing sodium glutamate with water as a by-product. Too wordy to understand this? Here’s a video that illustrates the process:

Due to various constraints, we can’t always eat the recommended amounts of fruits and vegetables we require to fulfil the daily requirement of vitamins and minerals. Similarly, we can’t put heaps of corns and cassava tubers to achieve the umami flavour that we want, right? Scientists have come up with processes to extract or synthesise vitamins and minerals into convenient capsules, and it is no different to how MSG is extracted for our convenience.

Of course, regular food contains glutamic acid too. Dietary protein (e.g., chicken and beef) have it as well, but due to it being bonded within the amino acids of the protein, it is not readily available to be tasted (glutamate needs to be “free” for it to be picked up by our taste buds). Adding salt would release some of these glutamates, allowing the food to taste better.

Some food has higher amounts of free glutamates, such as tomatoes (250-750mg), parmesan cheese (500-900mg) and soy or fish sauce (200-230mg). Mushrooms are also a rich source of natural glutamates that is often used in vegetarian or vegan meal preparations. Dr Fatimah went on elaborate on the daily dietary intake of MSG that was proposed by several countries.

Despite the total recommended daily intake above, we consume more MSG from natural sources: 10-12 g/d from foods sans MSG.

Glutamate is is a ubiquitous amino acid found in nature and it is important for bodily functions in the human body. It is an important substrate in energy metabolism, amino acid and protein synthesis, and glutathione synthesis (glutathione is a natural antioxidant in our body). Glutamate is produced from glucose in the brain, which acts as an excitatory neurotransmitter. Dr Fatimah glutamates are akin to “spark plugs” that is responsible for the transmitting of neurosignals in the brain. Aside from giving us that distinctive umami taste on our tongue, glutamate is also helpful in the digestive process by aiding nutrient absorption and metabolism and energy homeostasis via vagal nerve activation.

After the introduction, Dr Fatimah is now ready to debunk some fallacies about MSG. Several studies have shown that MSG carry adverse effects, but what people do not know about these studies is that these studies are what she called flawed science. The methods used in these flawed studies do not reflect how MSG normally enters the body. MSG normally enters the body orally and processed via digestion. Instead, these studies injected MSG into animal brain to overcome the blood brain barrier (BBB); some studies injected MSG straight into the bloodstream to skip the gastrointestinal (GI) barrier. Most, if not all these studies use a very high dose of MSG more than is normally consumed by humans. Of course, a combination of these methods and doses would cause toxicity and adverse reactions to the body, much like how an overdose of sodium and injecting sugar into the brain would cause unwanted effects.

One of the earliest flawed studies on MSG was in the 19600, that found that MSG the brain lesions, obesity, and other disturbances in mice treated with MSG. However, the study used new-born mice only two to eight days old and the MSG was given under the skin at a dose of two to five grams per kilogram. That would translate to 100 to 250 grams of MSG for a 50-kilogram man! Anyhow, the study showed that MSG damaged the hypothalamus of the brain, causing adult obesity and stunted growth in the mice. The effects of MSG here are indeed a cause for concern if the study was not presented in its full context.

Another study in 1971 was carried out on MSG, this time to study its effects on higher primates. The study was carried out on new-born primates and MSG was administered with a reasonable dose via a normal intake method. The study found that MSG intake has no adverse effect on the hypothalamus when administered via milk.

Next, Dr Fatimah explained how MSG enters the bloodstream. It normally starts from the mouth from the food we eat. When it enters the GI tract, around 95% is absorbed by the body in the small intestines, where it will be absorbed and utilised in energy production and protein synthesis processes. The rest of the MSG will be absorbed by the liver and used to create other amino acids or other processes. Very little of MSG is absorbed into the bloodstream, unless someone has GI issues especially in the small intestines where MSG is mostly absorbed.

Dr Fatimah went on to cite another flawed scientific study that highlighted the “dangers” of MSG. Robert Ho Man Kwok is a biomedical researcher who wrote a letter to the editor in the New England Journal of Medicine describing his peculiar illness that he alleged to have arisen from Chinese restaurants – he dubbed this the “Chinese Restaurant Syndrome”. This syndrome is characterised by chest pains, flushing of the skin, headache, numbness, sense of facial pressure or swelling as well as sweating.

This was in the early days of MSG, where manufacturers have recommended four to six grams of MSG to be added to dishes to improve the palatability of food. Of course, people especially Chinese restaurant cooks would have abused this and thought “more is more”, adding more MSG to improve their dishes. This in turn would cause more adverse effects to happen to consumers. Aside from that, physiological changes could also be attributed to the negative effects of food, especially those from a different culture.

Since then, plenty of double-blind, placebo-controlled, and multiple-challenge studies were carried out to further prove the “Chinese Restaurant Syndrome”. However, these could not reproduce the adverse reactions to MSG when combined with food in normal concentrations. When added to broth in large concentrations, the result remains inconclusive. In fact, even those who took the placebo experienced the same reaction.

What about MSG, asthma, and allergies? Dr Fatimah presented four well-designed studies that have debunked a previous study that linked MSG to adverse asthmatic and allergic reactions. A study that linked MSG to obesity was also debunked by a subsequent study, or any greater prevalence of weight gain over five years.

Debunking scientific facts aside, it was also found that these early studies on MSG were inherently flawed and mired by xenophobia. The 2009 paper in Social History of Medicine by Ian Mosby (Historian of Food, Indigenous Health and Settler Colonialism) showed that plenty of assumptions were made about the “bizarre” and “exotic” food practices of Chinese cooking and showed that researchers somehow thought that MSG was more dangerous when put in Chinese cooking, compared to “normal” American cooking.

Dr Fatimah is also not here for the slander that is the alleged lack of studies on the safety of MSG. In fact, Dr Fatimah stated that an extensive toxicological database on MSG that includes acute, sub-chronic and chronic effects, reproductive toxicity, and teratology studies (the scientific study of congenital abnormalities and abnormal formations) in animals as well as clinical human studies. Additionally, Dr Fatimah stressed on the importance of understanding that risk is the product of the potential of something to cause harm (i.e., hazard) and the exposure. Simply put, “the dose is what makes the poison”.

The fear of MSG is so great that the International Glutamate Technical Committee (IGTC) was created. This is a scientific non-profit organisation under the Union of International Association (UIA). It consists of six regional bodies from 13 countries all over the world that supports glutamate research in the areas of physiology, biochemistry, pharmacology, and toxicology. The IGTC shares scientific and regulatory information on glutamates and its salts to national and international regulatory authorities. They also address scientific and regulatory questions on glutamate safety with a particular emphasis on their use in food for human consumption. And of course, they promote the use of glutamates as food ingredients, especially on the international level.

Despite the ample evidence showing that normal consumption of MSG does not affect humans, there are consumer activists as well as special individuals (who still experience side effects from MSG) that are campaigning against the use of MSG in products. Therefore, food standard codes have required for MSG to be labelled in packaged food, alongside the presence of peanuts and gluten. Some manufacturers also cater to people who do not want to consume MSG, with products that are advertised as “no added MSG”.

Concluding her presentation, Dr Fatimah wrapped up with several salient points. Glutamates are naturally found in foods, and can be industrially manufactured as well, the latter which has been done for more than a century. Either way, the body does not differentiate whether MSG is naturally present in food or is artificially added. Several global regulatory agencies have considered MSG to be a safe food additive. Dr Fatimah added that MSG intake could also reduce sodium intake. Glutamate also plays a part in the physiological functions of the human body such as the digestive process, as well as nutrient absorption and metabolism. Lastly, Dr Fatimah emphasised that MSG consumption in food is safe!