Glutamic acid is produced naturally in the human and mammalian body. It is naturally present in the meat we eat and is responsible for the pleasurable taste of 'umami' which makes meat taste good. So if this is the case, then why does glutamic acid (aka MSG) cause a negative reaction in some people?
I don't question whether MSG has negative effects on some people: it has on me and many people I know. I take it for granted, and I hope the following quote is enough to prove my point:
"MSG treated rats and mice produce offspring that have learning problems, eating disorders and need glasses because their eyesight isn't very good after the MSG treatment." (Source: http://www.medicalcorps.org/fat-rat.htm)
Now, moving on to Eva's question: like Ed, I also think that it's probably only a matter of higher concentration and/or quantity in the artificial version. It is telling, that foods high in naturally-occurring MSG are also in a more or less "concentrated" form: dry mushrooms, sun-dried tomatoes, cheese, and they can cause problems to people especially sensitive to glutamate.
It would make a lot of sense that the body struggles to properly metabolize a high/concentrated MSG intake, with the many ill effects people complain about. Being a neurotransmitter and a potential excitotoxin there is a lot that can go wrong with an artificial version of it.
First of all, glutamic acid and MSG are not exactly the same. Glutamic acid is the amino acid form of the compound, chemical formula C5H9NO4, which is a natural part of proteins. Glutamic acid can also be made in the human body, since it is a non-essential amino acid.
MSG is the sodium salt of glutamic acid, chemical formula C5H8NNaO4. It occurs naturally, but is also manufactured and added to foods as a flavor enhancer.
I suspect that the side effects from consuming MSG are related to dosage and rapid absorption rather than to an allergy. If you were truly allergic to it, you could not consume anything with protein in it, since some MSG is formed after hydrolysis of proteins in your intestines. MSG is a water-soluble salt and can be rapidly absorbed from the stomach without requiring passage into the small intestine (unlike intact proteins).
I am procrastinating, but this is a great example of why skepticism is important for those of us in the niche health community. When you see a study you need to look at whether it was :
in vivo or in vitro. In vivo is in real life living creatures. In vitro is in cultures. Lots of things are toxic in vitro that are not toxic in vivo like vinegar or hot peppers.
abnormally large amounts administered. Like in Masterjohn's Jimmy Moore interview with the million peanut butter sandwiches, animal studies often use ridiculous amounts per body weight mass that you'd never encounter even in the worst Chinese restaurant. The oral admin to maternal rats study required the rats to eat the equivalent of me (a 110 lb woman) eating half a pound of MSG a day!
administration technique. The " Effect of perinatal monosodium glutamate administration on visual evoked potentials of juvenile and adult rats. " study above INJECTED baby rats with MSG. When was the last time you injected MSG into yourself.
I'm not saying MSG is good or harmless, I'm saying nearly all the evidence against it presented here is garbage.
The strongest evidence against it is how it is used as an agent of hyper-palatability, IE to make foods that abnormally palatable and encouraging overeating.
A comprehensive review of the scientific data conducted from 1992 to 1995 by the Federation of American Societies for Experimental Biology (FASEB), an independent group of scientists, at the behest of the FDA, found no connection between MSG and any short- or long-term health problems. Nor did it find evidence linking MSG or other glutamates to Alzheimer's disease, Huntington's disease or neurodegenerative diseases, although articles in the media have suggested such a connection.
However, the FASEB review did conclude that people who eat large amounts of MSG (three grams or more per meal) on an empty stomach and people with severe and poorly controlled asthma can develop such symptoms as numbness, burning sensation, tingling, facial pressure or tightness, chest pain, headache, nausea, rapid heartbeat, drowsiness and weakness. Note that three grams is a lot of MSG. The amount in a typical serving of food to which MSG is added is less than 0.5 grams.
However, researchers have found no definitive evidence of a link between MSG and these symptoms. Researchers acknowledge, though, that a small percentage of people may have short-term reactions to MSG. Symptoms are usually mild and don't require treatment. The only way to prevent a reaction is to avoid foods containing MSG.
I'm in the camp that thinks that MSG is probably rather benign for most.
Dr. Eades (Protein Power) blogged on MSG a few years ago: http://www.proteinpower.com/drmike/uncategorized/savory-monosodium-glutamate/
Another 2008 NY Times article about the stigma of MSG: http://www.nytimes.com/2008/03/05/dining/05glute.html?_r=2&pagewanted=1&th&emc=th
there is no question that MSG sensitivity is real for certain people. i was one of them. my suspicion is that a leaky blood-brain barrier (often goes together with leaky gut -> similar mechanism) is one of the main causes. also, some nutrient deficiencies can worsen the problem, as the brain normally has some metabolic mechanisms to protect from too high glutamate levels. -> heal the gut and BBB (get off gluten, restore gut flora, avoid food allergies), and supplement with known neuro-protective agents like Theanine, P5P, B12, Magnesium, etc.
btw, there is an easy way to test how leaky your BBB is: take 1-2g of GABA (e.g. 2 caps of http://is.gd/KZGFGe), if you feel anything (sleepiness, relaxation), your brain "leaks". (GABA and Glutamate normally can not readily cross the BBB - only when it's leaky)
The two things I have read in my own research is that naturally occuring glutamate is all pure L form glutamate. So if you eat meat, the naturally occuring glutamate you are consuming is supposedly all the same pure form your own body makes and uses. Whereas glutamate made artificially (ie not produced by the flesh of a mammal) is not 100% pure and has other forms of glutamate as well that might have strange effects. Our body has a lot of glutamate receptors all over and when we eat artificial glutamate that is not all in the form that is natural, it supposedly can have strange and unpredictable effects. Consider that glutamate is also a neuro transmitter, thus making it not surprising that intake of artificial impure glutamate could even have an effect directly on the brain. I liken it to the potential effects of eating a lot of oxidized PUFA in grain oil. If eating this PUFA, you are eating fat, and body takes it and makes use of it in your cell structure, but yet it is not the fat that is best for you to actually have in your cell structure. This grain oil PUFA is basically similar enough to natural fat that your body will take it up and use it, but the difference in it is enough to cause healthy problems. Perhaps the diff between natural glutamate and artificial glutamate can cause a similar scenario. SImilar enough to be taken and utilized by the body, yet different enough to cause problems, and the problems being more obvious and immediate in those that are more sensitive. Something to think about anyway.
This is a good article from a few years ago in the Gardian newspaper on the subject of MSG.
I'm gonna use Dr. Mike Eades' response to a similar question on his MSG article (which is quite good btw):
Mike, have you read Excitotoxins: The Taste that Kills by Russell Blaylock?
His credentials seem solid and he believes MSG is neurotoxic, as it crosses the blood-brain barrier and “over excites” neurons. I’d be interested if it does (or obviously hasn’t) changed your thoughts on this subject.
*Hi John– Yes, I’ve read Excitotoxins. And I found Dr. Blaylock’s arguments convincing until I dug a little deeper. It turns out that glutamate does indeed ‘excite’ neurons, and does so by allowing calcium to enter the cells. This excitation of the neuron is offset by the ‘calming’ influence of GABA, which acts in opposition to glutamate. The GABA-glutamate axis in the brain is much like the insulin-glucagon axis in the metabolic system. One needs both to function properly. Since the tiny bit of MSG used to season foods breaks down into glutamate and sodium – both normal constituents of the human body, and, in the case of glutamate, actually made by the human body – it’s difficult for me to image how a little bit of glutamate added to the body’s large circulating stores could substantially influence the neurons. If taken in large amounts, perhaps, but a pinch, occasionally, I don’t think will hurt. And maybe if a person is deficient in magnesium there could be a problem. Magnesium is Nature’s calcium channel blocker, so inadequate magnesium might not offset the influx of calcium driven by glutamate. This is just a hunch, but, because – according to the latest survey I read – about 75 percent of Americans don’t even get the already-too-low RDI of magnesium, maybe it’s the widespread magnesium deficiency that allows whatever negative effects experienced by some people when consuming a lot of MSG to happen. I don’t have magnesium consumption figures at hand for the Japanese, but given what they eat, I would assume they get a lot more magnesium in the standard Japanese diet compared to what we do in the standard American diet. The strongest argument for the harmlessness of MSG is the fact that it’s used in such large quantities in Asia by enormous numbers of Asians without any apparent epidemic of negative effects. The Japanese, for example, use MSG (and believe it’s healthful) in large quantities and outlive everyone else on earth despite the fact that most of them smoke. And they’re blowing the tops out of all the admission processes in American colleges, leaving US students in the dirt, so it can’t be affecting their cognitive abilities. If MSG were truly harmful, I would suspect the Japanese would suffer its ill effects. But, again, perhaps the greater intake of magnesium by the Japanese is protective. Which may be why they live longer, after all. Cheers– MRE