Monosodium Glutamate

So recently I've been trying to learn more about food additives, cause I used to be scared of aspartame. Today's lesson: Monosodium Glutamate, known as "Natriumglutamat" in Swedish.

First thing that surprised me: It occurs naturally, in extremely high quantities, in most Chinese and Japanese cuisine, including soy beans and seaweed. The artificial food additive is produced by fermentation of foodstuffs rich in carbohydrate, meaning essentially it's made in the same way as yoghurt is made out of milk: Some bacteria nibble on starch, and poop the stuff out.

All in all, that doesn't sound very "artificial" to me. However, there's an important distinguishing factor: Where it occurs naturally, it's evenly divided between D-glutamate and L-glutamate. I'm no chemist, but as far as I can tell, this means their molecules are mirror images of each other - one of them faces left, the other one faces right (in terms of polarization, I would presume, but I don't know). In the food additive MSG, however, 99% the sodium glutamate is forcibly turned into L-glutamate, which is richer in flavour. This might not sound like a big deal, but this can be the difference between a substance being healthy or outright poisonous.

So MSG is bad, because there's an unbalance between left and right? Maybe, but apparently this unbalance can and does occur naturally; soy sauce contains 95% L-glutamate, as does most kinds of steak sauce, and in this case it isn't a chemical additive; it just naturally ferments that way.

Does this substance carry any documented health risks? Only one has been taken seriously by the scientific community; MSG is an excitotoxin, meaning it puts severe stress on nerves if it comes in contact with them. The catch? The stuff can't pierce the blood-brain barrier, so it can't actually reach any important nerves. Not all of the brain or the nervous system is protected by this barrier, however.

Conclusion? Well, the articles I've read are inconclusive. On the one hand, glutamic acid is necessary for our brains to function at all (glutamate is an important neurotransmitter), on the other hand, it may be possible to OD on L-glutamate but nobody knows what this might do. The only thing I've found any solid evidence for, is that MSG does cause weight gain, but that's hardly a surprise.

Sources: Wikipedia, Associated Content, Worldfoodscience.org