Saturday, October 17, 2009

What is MSG?

Kikunae Ikeda

Kikunae Ikeda

Monosodium glutamate (MSG) is the sodium salt of L-glutamic acid, a naturally-occurring nonessential amino acid, which makes up about 10-25% of all food protein.

MSG has been added to foods as a flavor enhancer for over 100 years—ever since Kikunae Ikeda purified it from dried kombu (seaweed) in 1908. It has been the subject of hundreds of medical studies, but every regulatory agency in the world has concluded that MSG is safe for human consumption. This isn't surprising because measurable amounts of natural free glutamate exist in practically all foods with protein.

What the heck is a nonessential amino acid?

L-glutamic acid is an amino acid, one of the 20 amino acids contained in all natural protein. It's a "nonessential" amino acid because humans don't need to consume any of it in a healthy diet. Instead, the human body synthesizes glutamic acid on an as-needed basis.

Glutamic acid is highly soluble in water, and it's a weak acid, so it has two interchangeable forms—glutamic acid and glutamate, which is the conjugate base (the same compound without the H+ ion).

Glutamic acid is of of the most abundant amino acids in the human body, and one of the most common amino acids in nature. Anything with protein contains glutamate, and glutamic acid typically constitutes 10-25% the weight of animal and vegetable protein.

What makes MSG any different from the glutamate found in all protein?

Two amino acids

peptide bonds link amino acids together as protein

MSG is "free" glutamate—the unbound form of glutamic acid, unattached to a protein.

Proteins are complex molecular structures built by the peptide bonds between hundreds or thousands of amino acids. Most of the amino acids you eat are bound as protein, and they don't break down into free amino acids until they are hydrolyzed by stomach acid and intestinal enzymes into individual amino acids.

That said, practically anything with protein will contain some hydrolyzed protein (and therefore free glutamate). Free glutamate is chemically indistinguishable from added MSG.

Foods contain free glutamate for several reasons. First, organisms necessarily keep a supply of free amino acids on hand for synthesis, and these will be present in the foods you eat. Second, when cells die—as when tomatoes ripen—more of their proteins become hydrolyzed. Third, the heat of cooking hydrolyzes some protein, including glutamate. Finally, and most importantly, the traditional process of fermentation hydrolyzes tons of protein, and much of this hydrolyzed protein is necessarily free glutamate.

Therefore, many foods with absolutely no added MSG nevertheless contain significant concentrations of free glutamate, especially fermented foods like cheese and sauces. Here are the natural concentrations of glutamate in food:
  • Marmite, 1.96%
  • Vegemite, 1.43%
  • Parmesan cheese, 1.2%
  • Soy sauce, about 1%
  • Ketchup, about 0.4%
  • Steak sauce, about 0.35%
  • Tomatoes, 0.24%
  • Peas, 0.2%
  • Worcester sauce, 0.14%
  • Meats, 0.02-0.07%
  • Human breast milk, 0.022%
How is commercial MSG produced?MSG crystals

MSG crystals

Monosodium glutamate is predominantly made by the yeast fermentation of high-calorie food products like corn starch and corn syrup. The largest producer of MSG in the world, Ajinomoto, makes MSG from this process using a yeast strain genetically engineered to produce an excess of glutamic acid.

MSG manufactured by this fermentation process has exceptional purity of about 99.5% L-glutamate. Contrary to some of the MSG misinformation online, industrially-isolated MSG contains almost no D-Glutamate. In fact, natural sources of glutamate contain more of this impurity than the MSG added to foods.

Why does free glutamate enhance the flavor of foods?

Only the unbound form of glutamate enhances the flavor of foods. On the tongue, MSG produces a savory sensation that the Japanese call umami; a fifth taste besides salty, bitter, sweet, and sour. Receptors on the tongue sense the active groups of MSG, which combines especially well with aromatic tastes like garlic and curry. Free glutamate is the reason so many traditional foods around the world taste so good. (Yes, MSG, The Secret Behind the Savor, NYT)

Most people in the west cannot accurately identify the taste, but in East Asia, it's a well-known flavor in traditional cooking. I first recognized it as the common sensation in Parmesan cheese, KFC gravy, and Doritos tortilla chips.

Glutamate is the flavor of protein; it makes things taste meatier and more savory than they actually are. Like salt, too much MSG makes food taste worse; above 1% MSG, food starts to taste more like dried ramen seasoning—simplistic, salty, and bad.

The bottom line: is MSG safe?


It's been thoroughly studied and is approved as safe by every regulatory agency on earth. Here are some comprehensive reports on the subject:
"But," you might be thinking, "wasn't smoking once considered safe according to regulators? Why should we trust the regulators to protect our health?"

Personally, I don't necessarily trust them, but in this case we can look at robust and independent data to see for ourselves that MSG is no more harmful than table salt. In particular, consider how MSG has been widely used in Japan for about 100 years. Several generations of widespread MSG consumption have not stopped the Japanese people from being one of the healthiest and longest-living nationality on earth. Indeed, Japanese have only recently begun to have American-style problems with obesity now that some residents are eating American-style junk food and living sedentary lifestyles.

MSG doesn't make Americans unhealthy. Poor nutrition and lack of exercise make us unhealthy. Blaming MSG is actually symptomatic of the greatest American health problem—our laziness.

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