The Science And Myth Of Aji-no-moto

By Tharosa Missaka Rajaratne –JANUARY 23, 2019

Tharosa Missaka Rajaratne

Commonly called food myths such as “chocolate is an aphrodisiac”, “garlic induces fever when kept under one’s armpit” and many other are heard from every corner of the world since the beginning of the human order. But along with scientific advancement, human kind learned to scientifically explain some of these phenomena. However, controversies prevail among the commoner either due to extreme social beliefs or complexity of scientific explanations to those phenomena. Extreme social beliefs are often caused by hoaxes which pass down from generations. For instance, many Sri Lankans tend to believe that and foreign foodstuffs are unhealthy and thus their consumption cause cancer, infertility, and bone decay etc. Most of these beliefs lack scientific evidence or explanations and are strictly based on either hypothetical or isolated incidents which everyone claims as “thus have I heard”. Monosodium glutamate (MSG), better known as ‘Aji-no-moto’, has confronted with tremendously discussed culinary myths. Unlike other countries do, Sri Lanka generally perceives completely different beliefs about MSG. In the recent past, MSG gained attention in Sri Lankan media after revelation of alleged usage of it as an effective substitute to the notorious herbicide Glyphosate which was banned from importing. This raised alarm in the country that MSG is not only carcinogenic, as previously claimed, but also is extremely toxic and thus it causes bone decay, cancer etc. This social perception encouraged examination of scientific literature of MSG. This review thus intends to distinguish science from myths of MSG.   

HISTORY OF MSG AND AJI-NO-MOTO:

During the early 1900s, Kikunae Ikeda, a Professor of Chemistry at the Tokyo Imperial University of Japan, conducted a series of tests on a popular seaweed known as Kombu (Laminaria japonica), an ingredient of many Japanese cuisine, after noticing that whenever Kombu was assimilated with the Japanese broth Dashi it produces savory-like taste, which did not fit into any of the scientifically described basic tastes at that time: sweet, sour, salty, or bitter. Moreover, he learnt that the addition of Kombu would likely enhance the overall flavor of the broth, and thus named this new unknown class of flavor as “Umami”, which translates roughly into ‘savory’ in Japanese. This new class of flavor is now widely accepted as the fifth taste.

The flavor enhancing component was determined to be the Glutamate ion and was extracted as its Single Sodium salt Monosodium Glutamate (MSG). His aims were to extract the flavor-causing compound as a stable solid, and also to commercialize the process, which resulted in the establishment of the popular brand “Aji-no-moto” (味の素) in 1917. The word Aji-no-moto gives a compound meaning derived from each Chinese character: Aji – Taste, no – of, Moto – Essence. And so the literal meaning is “essence of taste.”  Yet the contextual meaning of Moto also refers to refining and enhancing. Therefore, the meaning of Aji-no-moto could also be identified as “Refiner of Taste” or “Taste Refiner.” Starting from a production of mere 4.7 tons in Japan in 1910 and continuously increasing into multi-million ton, multinational production of MSG as of now since the establishment, Ajinomoto Co. has secured themselves as the tycoon in the MSG industry and acquired an undisputed monopoly in branding to the extent that MSG to be colloquially recognized as Ajinomoto among the commoner. Three methods have been employed to produce MSG throughout its history; Hydrolysis of vegetable proteins with Hydrochloric Acid (1909-1962), Chemical Synthesis with acrylonitrile (1962-1973), and Bacterial Fermentation (Current Method). The fermentation process is much similar to that of any other ordinary yogurt or vinegar making method and the ingredients used are generally tapioca, sugar beets, sugar cane, and molasses. Upon the production of MSG in a commercially feasible stage, MSG was available to be purchased conveniently more than ever and was used extensively in the East and South Eastern cuisines like Chinese, Korean, and Japanese.

MSG AND CHINESE RESTAURANT SYNDROME:

The inception of social discontent towards the usage of MSG emerged in 1968, after a paper was published in the New England Journal of Medicine by Robert Ho Man Kwok in which he described a list of symptoms he experienced after eating at Chinese Restaurants. His symptoms included “numbness at the back of the neck, gradually radiating to both arms and the back, general weakness and palpitation” (Kwok, 1968). Furthermore, he suggested various possible causes for the aforementioned symptoms, of which the usage of alcohol, salt, and MSG in cooking were prominent. Since the symptoms developed mainly via Chinese restaurants, the author coined the complex of symptoms as Chinese Restaurant Syndrome (CRS). Since then, numerous self-limited and isolated incidents relating to CRS started to appear in the society alongside Kwok’s paper, and MSG was mainly focused and often blamed to be the cause of CRS.

The list of symptoms has since then been updated adding to it more symptoms such as headache, flushing, muscle tightness, and asthma attacks etc. The scientists have been conducting an array of tests to verify the role of MSG as a causative of CRS but they have made no conceivable explanation so far. Sodium Glutamate: A Safety Assessment (Food Standards Australia New Zealand, 2003) is a scientific assessment report that presents in-depth analyses of Kinetic and metabolic activity of MSG and scientific reviews of previously conducted experiments on MSG and CRS. These tests have been conducted as double blind placebo controlled experiments (DBPC) to minimize experimental bias since most of the participants were self-identified as MSG sensitive. Notable studies of this sort include Tarasoff and Kelly (1993), Yang et al (1997), and Geha et al (2000). Almost all the studies have failed to show any broad statistical correlation of MSG as CRS causative because many participants failed to produce consistent observations (symptoms) to each relevant test (the MSG containing test), showing that the MSG is very unlikely to have a correlation with CRS symptoms among the participants. It also should be noted that while the average consumption of MSG in the United Kingdom is 0.59 g/day and extreme consumption (Consumers of the 97.5th percentile) is 2.33 g/day (United Kingdom – Rhodes et al, 1991)), some of these tests conducted have administered extreme doses of MSG such as 6 g (Altman et al, 1994), 7.6 g (Germano et al, 1991), 18.5 g (Wilkin, 1986), 147.0 g (Bazzano et al, 1970) per day to the participants, which are very unlikely to be have ingested in practical customary levels even at extreme occasions, have shown that the symptoms were irreproducible with consistency.

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