MSG: MORE THAN MEETS THE TONGUE
Most of our lives are spent obtaining food, preparing food, cooking food, and taking the time to savor food. Food is colourful, flavorful and simply delightful. The only drawback is wondering what our next meal is going to be. A simple solution for most working class people in the world: eating out. With such an abundance of neighborhood fast-food restaurants or take-out place at competing prices, eating out has become the latest trend in filling the stomach of many. In fact, the idea of purchasing pre-cooked meals has become such a widely accessible concept that people choose this alternative over the time- and energy-consuming method of simply cooking their own meals. However, there are consequences to this alternative.
Although we have a mindset of what unhealthy food is, sometimes ignorance is bliss, and a full stomach is all we need in order to continue with our day’s work. We constantly worry and monitor our fat and caloric content of what we eat; however, there may be more important aspects that we should be worried or concerned about. For example, monosodium glutamate, or more commonly known as MSG, is added to almost every fast food and take-out meal we eat. The majority of people pay no attention to it simply because they are either unaware of its presence in food or are unsure of what MSG really is. MSG may have more detrimental effects on the human body than simply being a food additive. So what exactly is MSG? Why is it added to foods? What are its effects on the human body? Is it harmful even though it is approved by the Food and Drug Administration (FDA)?
Monosodium glutamate (MSG) has been used as a flavor enhancer for over a century. In 1908, Kikunae Ikeda, a Japanese scientist, extracted glutamic acid from the seaweed Laminaria Japonica and discovered its flavor-enhancing properties, thus was the birth of MSG. MSG is a free amino acid salt with one sodium atom attached to the amino acid glutamate. Amino acids are basic building blocks linked together to form larger proteins. However, there are amino acids that aren’t linked and perform vital functions on their own. For example, glutamate is an excitatory amino acid neurotransmitter, that is, a chemical messenger that triggers the nerve cells to fire. Glutamate is naturally made in the human brain and present within the muscle, kidney, and liver.
Not only is glutamate naturally made in our bodies, but exists in many of the foods we eat, such as, parmesan cheese, tomatoes, mushrooms, walnuts, etc. This is why many of these foods are used as flavor enhancers for various dishes. However, the food industry is not satisfied and wishes to harness this flavor enhancer so it can be added to all foods. As a result, MSG is created by hydrolyzing vegetable protein or by fermenting corn and starchy foods. The final product of MSG is a white crystal that can easily dissolve into foods. The MSG manufacturers argue that processed MSG is a pure salt exactly the same as the glutamate in our bodies, whereas, the MSG antagonists argue that processed MSG is impure and also contains a different isomerism, a mirror image of glutamate from the ones naturally made in our bodies. Moreover, by hydrolyzing vegetable protein, glutamate becomes “free” and is able to act as a neurotransmitter. Excess free glutamate can, as argued by neuroscientists, lead to many disease states.
MSG in foods acts through our taste buds on the tongue giving us the “umami” taste sensation, which means delicious in Japanese. This “umami” taste is termed the fifth taste sense of our basic tastes, and is described as meaty, brothy, and savory. From the tongue, this signal is relayed up to the cerebral cortex in the brain telling us that what we’re eating is delicious. Ingested glutamate is absorbed through the intestines, where it is transaminated and subsequently, metabolized by the liver leading to the release of glucose, glutamine, lactate, and other amino acids into the blood circulation. Glutamate is not considered to be an essential amino acid since we are able to produce it ourselves, but constant excess of glutamate from oral ingestion could lead to other problems.
MSG has various detrimental effects, which include triggering asthma attacks and exacerbating migraine headaches. Studies have shown that oral ingestion of MSG can provoke asthma attacks in patients diagnosed with asthma, and bring about symptoms of the Chinese Restaurant Syndrome (CRS). The CRS is a collection of symptoms that include sweating, headache, flushing, and in more serious cases, swelling of the throat and chest pain. Although it was believed that MSG is the cause of CRS, no empirical studies have found a causal link between them. There have been studies showing MSG to exacerbate migraine headaches as well. Excess glutamate, acting as an excitatory neurotransmitter, causes over stimulation in the brain prolonging the migraine attacks. In more serious cases, MSG may even cause neuronal death due to over stimulation.
Not only is MSG found to induce asthma and migraine attacks, but is also linked to diseases such as obesity, Type 2 diabetes and Alzheimer’s disease. Metabolizing glutamate after a MSG-rich meal induces the release of glucose into the blood stream. This in turn triggers the secretion of insulin by the pancreatic islet cells, so that muscle cells can take up glucose. Obesity is characterized, in part, by high levels of plasma glucose and insulin. Studies have shown that mice injected with MSG became obese and eventually lead to insulin-resistance and the onset of Type 2 diabetes. Moreover, MSG has been shown to stimulate appetite in humans. Subjects that had MSG-rich meals exhibited more stimulation to eat and ate more often than control subjects. The elderly are more susceptible to over stimulation of the brain caused by MSG, and risks degeneration of nerve cells in the brain leading to Alzheimers.
In spite of the detrimental effects of MSG, the FDA approves of MSG in our food products based on its “naturally occurring” ingredient. Because glutamate is also found in nature, MSG is a safe food additive. Many manufacturers rename the monosodium glutamate ingredient to euphemistic terms such as, malt extract, corn syrup, cornstarch, or hydrolyzed “anything”.
So why do food companies and restaurants add MSG to foods in spite of the problems it causes? MSG fools your brain into believing you are consuming nutritious and tasty food, stimulates appetite, and reduces costs for the food processors. Glutamate triggers the umami taste sensation and leads you to believe the food in your mouth is high in protein and nutritious. For example, simply adding MSG to a bowl of noodle soup immediately adds a savory taste to it, bringing the misconception that the soup is truly delicious. MSG stimulates appetite by inducing insulin release so that glucose is taken up, despite not having consumed anything with carbohydrates (sugars). As a result of high insulin concentrations, your blood sugar level drops and you end up being hungry again only hours later. Because MSG gives the impression of tasty and savory food, it allows food processors to put in less of the real food. For example, fast-food restaurants have mastered this technique in their beef patties for their burgers. Adding MSG to the beef patties gives the same meaty, savory taste as real beef. Therefore, fast-food processors have no need to use a 100% beef patty, and thus are able to reduce costs. MSG is practically the most profitable ingredient in the food industry – stimulating palability so that consumers eat more or come back for more while cutting costs in their food products all at the same time.
Monosodium glutamate is only one of the many ingredients we should be aware of before consuming any food product, whether from home or (especially) at restaurants. Those with asthma or are susceptible to migraine should be even more conscientious. Although we cannot control what the food industry does as a whole, we do have the power to choose what food we eat. As technology advances, many ingredients become processed, and foods become engineered. Food processors may take advantage of lower costs and disregard how healthy their food products really are. We must raise our awareness to what we consume, and what we allow our children to consume, for there may not be any real, natural food in the future.
References
1. Allen DH, Delohery J, Baker G. 1987. Monosodium L-glutamate-induced asthma. J Allergy Clin Immunol. 80 (4): 530-537
2. Bellisle F. 1999. Glutamate and the UMAMI taste: sensory, metabolic, nutritional and behavioural considerations. A review of the literature published in the last 10 years. Neuroscience and Biobehavioral Reviews. 23: 423-438
3. MSG – Slowly Poisoning America. [online]. Available here. [accessed 10 February 2007]
4. Nagata M, Suzuki W, Iizuka S, Tabuchi M, Maruyama H, Takeda S, Aburada M, Miyamoto K. 2006. Type 2 diabetes mellitus in obese mouse model induced by monosodium glutamate. Exp. Anim. 55 (2): 109-115
5. Scher W, Scher BM. 1992. A possible role for nitric oxide in glutamate (MSG)-induced Chinese restaurant syndrome, glutamate-induced asthma, ‘hot-dog headache’, pugilistic Alzheimer’s disease, and other disorders. Med Hypotheses. 38 (3): 185-188
6. Thirone AC, Carvalheira C, Hirata AE, Velloso LA, Saad MJ. 2004 Regulation of Cbl-associated protein/Cbl pathway in muscle and adipose tissues of two animal models of insulin resistance. Endocrinology 145 (1): 281-293
7. What exactly is MSG? [online]. Available here. [accessed 10 February 2007]
8. What is MSG? [online]. Available here. [accessed 10 February 2007]
