I'm a little troubled by some articles I've come across on certain web sites (www.msgmyth.com or www.truthinlabeling.com, or articles by Russell Blaylock) arguing about potential health risks (notably potential neurocognitive health issues) with the consumption of MSG or even foods naturally possessing reasonable quantities of non-protein bounded ("free") L-glutamic acid.
The basic argument proposed is that exposing oneself to a sufficiently high oral bolus dose of "free glutamate" will cause these compounds to reach the bloodstream quickly and potentially overexcite neurons, leading to potential damage. From what I've come across, such claims neglect the facts that 1) the GI tract metabolizes much of the glutamate present in foods (often to assist in the digestion of carbs), 2) that the liver itself also converts glutamate to glutamine or other intermediaries (alpha ketoglutrates, etc.) - and all digestion products generally must go through the liver via the portal vein before reaching general systemic circulation, and 3) the blood brain barrier blocks the passage of glutamate to neural tissues.
But notwithstanding these barriers, I'd like to know what forum members feel about the glutamate controversy, and particularly, whether naturally present glutamate in unprocessed foods can pose any risks.
While I have no qualms about avoiding MSG (which allegedgly also contains D-glutamic acid, pyroglutamic acid and other "impurities" along with L-glutamic acid), I'm not very convinced that foods such as tomatoes, walnuts, peas, or broccoli should be restricted or avoided notwithstanding MSG industry claims that these foods possess more "free glutamate" than foods with added MSG seasonings. Please see http://www.msgfacts.com/chart.html, an industry-sponsored website that claims that walnuts have 658mg of free glutamate per 100g of food (along with other assertions for other foods).
So basically, should we be concerned in any way about the alleged "free glutamate" content of foods otherwise assumed to be very healthful and supportive of cognitive health (like walnuts, rich in ellagic acid and ALA, or tomatoes, broccoli)? Is it wise or sensible to restrain or limit the consumption of walnuts in an individual sitting to avoid exposure to allegedly high levels of free glutamate?
I tended to eat about 5-10 whole walnuts a day, on average, until I saw the msgfacts.com website.
And what about other nuts (like almonds, pecans, brazil nuts, hazelnuts, etc.) or seeds (pumpkin, flax, sunflower, sesame)?? Does anyone know what kind of "free glutamate" contents such nuts may have?
Any feedback would be greatly appreciated.
Edited by michalhachto, 11 January 2009 - 02:30 PM.
