dr_mabeuse
seduce the mind
- Joined
- Oct 10, 2002
- Posts
- 11,528
From Wiki
ecause glutamate is absorbed very quickly in the gastrointestinal tract (unlike glutamic acid-containing proteins in foods), glutamate could spike blood plasma levels of glutamate.[8][9][10] Glutamic acid is in a class of chemicals known as excitotoxins, high levels of which have been shown in animal studies to cause damage to areas of the brain unprotected by the blood-brain barrier and that a variety of chronic diseases can arise out of this neurotoxicity.[11][12] The debate among scientists on the significance of these findings has been raging since the early 1970s, when John Olney found that high levels of glutamic acid caused damage to the brains of infant mice ("Olney's lesions").[13] The debate is complex and has focused mainly on whether the increase in plasma glutamate levels from typical ingestion levels of glutamate is enough to cause neurotoxicity and on whether humans are susceptible to the neurotoxicity from glutamic acid seen in some animal experiments.
At a meeting of the Society for Neuroscience in 1990, the delegates had a split opinion on the issues related to neurotoxic effects from excitotoxic amino acids found in some additives such as monosodium glutamate.[14]
Some scientists believe that humans and other primates are not as susceptible to excitotoxins as rodents and therefore there is little concern with glutamic acid as a food additive.[15][16] While they agree that the combined effects of all food-based excitotoxins should be considered,[17] their measurements of the blood plasma levels of glutamic acid after ingestion of monosodium glutamate and aspartame demonstrate that there is not a cause for concern.[18]
Other scientists around John Olney felt that primates are susceptible to excitotoxic damage[19] and that humans concentrate excitotoxins in the blood more than other animals.[20] Based on these findings, they feel that humans are approximately 5-6 times more susceptible to the effects of excitotoxins than rodents are.[21] While they agree that typical use of monosodium glutamate does not spike glutamic acid to extremely high levels in adults, they are particularly concerned with potential effects in infants and young children[22] and the potential long-term neurodegenerative effects of small-to-moderate spikes on plasma excitotoxin levels.[23]
[edit] Obesity
In 2008, researchers at the University of North Carolina at Chapel Hill, working with Chinese researchers, published a study that found a positive link between MSG intake and obesity in humans. Moreover, prevalence of overweight was significantly higher in MSG users than in non-users. The population in this study was 752 healthy rural Chinese villagers between the ages of 40 and 59, of whom 48.7% were women. [24] [25]
Previously, monosodium glutamate has been shown to indirectly cause obesity in lab rats by downregulating hypothalamic appetite suppression and, thus, increasing the amount of food the lab rats consumed. However, at least one study (1978) found that this obesity effect (widely utilized in obesity research using rats and mice, and also observed in Chinese hamsters) was not dependent on additional food intake. [26] Animal research demonstrating an inverse relationship between increased glutamate intake via maternal feeding and serum levels of growth hormone, combined with an epidemiological survey of 2,239,960 German adults demonstrating an inverse relationship between height and morbid obesity, compels some researchers to theorize (2006) that monosodium glutamate has a role in the occurrence of obesity in humans.[27]
However, an earlier study (1973) did not find a similar effect in humans. The epidemiological survey of 4938 ethnically Japanese men drawn from the Honolulu heart program in Hawaii found that self-reported dietary monosodium glutamate consumption was not statistically linked with obesity.[28][29] Researchers furthermore found that frequent monosodium glutamate consumption did not significantly affect blood sugar or serum cholesterol levels among the participants. A rat study conducted by the Institute of Life Sciences in Kawasaki, Japan during which the experimental rats were allowed to freely drink a solution of MSG and water actually showed a reduction in abdominal fat and weight gain compared to control rats. [30]
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I'm not sure what areas of your brain aren't protected by the blood-brain barrier. Brain stem, maybe.
Looks complicated. Looks like individual biochemistry may play a role.
It should be noted, though, that epidemiological studeis have shown no effect in the Chinese or people who are chronic users of MSG, so if it has any effect, it's anecdotal on a case-by-case basis and can't be proven statistically.
The wiki article starts off with a bunch of paragraphs citing reliable data verifiying MSG's overall safety. I didn't post it here, but all the science points to it being safe.
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