It would be remiss of me to write a weekly column about seasonings and avoid covering one just because it's controversial. Monosodium glutamate (MSG) is used quite openly in most parts of Asia but, in the rest of the world, its inclusion in food is much more furtive. Some manufacturers avoid listing MSG on their ingredients labels by using more innocuous words, such as "natural flavours", "hydrolysed vegetable protein", "soy protein" and "yeast extract", all of which contain MSG, but are not pure MSG.
At the turn of the last century, Japanese chemistry professor Kikunae Ikeda noticed that food cooked with kombu (giant kelp) tasted better. So, in 1907, he isolated the flavour-enhancing essence MSG into crystalline form, patented it and commercial production started soon after.
MSG is the sodium salt of glutamic acid, which is an essential amino acid found in all animals and animal products, as well as some vegetables. Glutamate-rich foods include tomatoes, peas, cheese and other milk products (including human milk), soy sauce, fish sauce and mushrooms.
MSG has been blamed for many ills, from migraines to obesity to Alzheimer's and, as such, has been relentlessly studied by scientists, doctors, people within the industry and people who want it banned. Double-blind studies that seem to prove that MSG has no adverse effect, even on people who say they are sensitive to it, have been dismissed by the many MSG-detractors. People who say they are adversely affected by the crystalline form of MSG should have a similar reaction to a plateful of spaghetti bolognaise with parmesan, a combination that has a heavy dose of glutamates.
As open as I am to MSG (as long as it's not overused, but that's how I feel about every other ingredient, too), I don't add the commercial product to my food; instead, I rely on other glutamate-rich products. But that's not to say I'll never use it.