MSG, an abbreviation for monosodium glutamate, is a flavor enhancer first introduced into the diet of Asian cuisine from seaweed extract, and later refined as a food additive by Kikunae Ikeda in Japan in 1907. Japanese soldiers had MSG included in their rations during World War II, and this was eventually noticed by American military forces, who brought it to the US in the late 1940s, where it became a household word by the 1960s. Monosodium glutamate is a naturally occurring amino acid that is not required by the human body for health, but glutamic acid from which it is derived is a common salt found in a wide variety of foods, and is often accounted for on labels as hydrolyzed protein, yeast, or soy extract.
Since MSG is so pervasive in the diet both in refined and natural forms, health concerns about its effects have been difficult to quantify. Every form of hydrolyzed protein, from sodium caseinate to autolyzed yeast, contains some form of glutamic acid from which MSG is derived. Large scale production of sodium salts began in 1956 when the Japanese perfected a method of fermentation at the Ajinmoto Company, which holds a patent on MSG. With increased distribution of the product to thousands of different food product lines, some health side effects began to be attributed to it.
Research in the late 1960s and early 1970s suggested potential toxicity issues for MSG, especially where it was being incorporated into baby food at the time. Food regulations in many countries from the US to Australia and New Zealand now require that all MSG be labeled as a food additive where it is used. Toxicology research as of 2004 has found that, even in large amounts, monosodium glutamate should be considered harmless.
Some difference of opinion exists on the effects of the refined form of MSG versus its natural sodium salt counterparts. By perfecting the manufacturing process, Ajinomoto Company has been able to produce MSG where 99.6% of the volume is made up of the L-glutamate flavor enhancing compound. Other unrefined forms of glutamic acids, however, typically have 95% or less of the L-glutamate chemical, so the differences are not too great. Whether MSG has long-term detrimental health effects or not, use continues to grow, with over 1.5 million metric tons of MSG consumed every year.
Aside from being used as a food additive, monosodium glutamate was discovered to be a useful component of plant growth. Glutamic acid derivatives are now incorporated into fertilizers and fungicides sprayed on everything from wine grapes to fruits, nuts, grain crops, and vegetables. In the US by the year 2009, the use of MSG had been approved for spraying on all agricultural products.