MSG Obese

[Nancy LC]

Someone on another web site suggested typing in the worlds "MSG obese" into the search box at pubmed (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed). Sure enough a large number of studies jumped up about rats who were fed MSG as pups and became obese as a result.

For instance:



Treatment of newborn mice with monosodium glutamate (MSG) is neurotoxic for hypothalamic arcuate nucleus (ARC) and causes obesity. In the MSG-treated 16-week-old NMRI mice, we detected specific ablation of ARC neuronal cells, 8 times higher fat to body mass ratio but unchanged body mass compared to controls, advanced hyperglycemia and hyperinsulinemia - both more pronounced in males, and hyperleptinemia - more severe in females. After fasting, the MSG-treated mice showed attenuated food intake compared to controls. Cholecystokinin octapeptide, which decreased food intake in a dose-dependent manner in 24 h fasted controls, did not significantly affect food intake in the MSG-treated animals. We propose that the obesity-related changes in the feeding behavior of the MSG-treated obese mice were the result of missing leptin and insulin receptors in ARC and consequent altered neuropeptide signaling. This makes the MSG model suitable for clarifying generally the central control of food intake.

and

Obesity, voracity, and short stature: the impact of glutamate on the regulation of appetite.

Is this why I can eat a bag of chips and never feel full? In fact, I want to eat more of them!

Here's an article about obesity and diabetes in MSG mice: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=16651693&query_hl=1&itool=pubmed_docsum

Unholy Glutamate! Is that the fuel behind the obesity epidemic?

[Nancy LC]

Just looking around a bit more and I found more explanations...

http://en.wikipedia.org/wiki/Monosodium_glutamate
Obesity

MSG has been used in newborn laboratory mice to induce adult obesity because of the lesions that it provokes in the arcuate nucleus of the hypothalamus. However, the blood-brain barrier (BBB) of newborn babies doesn't resemble the one of neonate mice, therefore, like in adults, glutamate has a low penetration level in the central nervous system[1]. Only the luminal membrane of the BBB contains facilitative carriers for glutamine and glutamate. In fact, the amount of free glutamate in breast milk is one of the highest among other mammals besides the chimpanzee.
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Excitotoxicity

Glutamic acid is an amino acid commonly found in foods. Because MSG is absorbed very quickly (unlike glutamic acid-containing proteins in foods), it is known that MSG could spike blood plasma levels of glutamate. [4] [5] [6] Glutamic acid is in a class of chemicals known as excitotoxins. Abnormally high levels of excitotoxins have been shown in hundreds of 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. [7] [8] The debate among scientists on the significance of these findings has been raging since the early 1970's, when Dr. John Olney found that high levels of glutamic acid caused damage to the brains of infant mice. [9] The debate is complex and has focused on several areas:

* Whether the increase in plasma glutamate levels from typical ingestion levels of MSG is enough to cause neurotoxicity in one dose or over time.
* Whether humans are susceptible to the neurotoxicity from glutamic acid seen in some animal experiments.
* Whether neurotoxicity from excitotoxins should consider the combined effect glutamic acid and other excitotoxins such as aspartic acid from aspartame.

At a meeting of the Society for Neuroscience, the delegates had a split opinion on the issues related to neurotoxic effects from excitotoxic amino acids found in some additives such as MSG. [10]

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 from MSG. [11] [12] While they agree that the combined effects of all food-based excitotoxins should be considered [13], 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. [14] Other scientists feel that primates are susceptible to excitotoxic damage [15] and that humans concentrate excitotoxins in the blood more than other animals. [16] Based on these findings, they feel that humans are approximately 5-6 times more susceptible to the effects of excitotoxins than rodents are. [17] While they agree that typical use of MSG does not spike glutamic acid to extremely high levels in adults, they are particularly concerned with potential effects in infants and young children [18] and the potential long-term neurodegenerative effects of small-to-moderate spikes on plasma excitotoxin levels. [19]. And yet, although may seem as a contradiction, human breast milk is one of the milks with the highest levels in free glutamate among mammals. [20] [21] [22]
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Ingredient listing
This article or section deals primarily with the United States of America and does not represent a worldwide view of the subject.
Please improve the article or discuss the issue on the talk page.
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United States

Under current FDA regulations, when MSG is added to a food, it must be identified as "monosodium glutamate" in the label's ingredient list. Each ingredient used to make a food must be declared by its name in this list.

While technically MSG is only one of several forms of free glutamate used in foods, consumers frequently use the term MSG to mean all free glutamate. The free glutamic acid component of MSG may also be present in a wide variety of other additives, including hydrolyzed vegetable proteins, hydrolyzed yeast, soy extracts, and "natural flavorings".

For this reason, FDA considers foods whose labels say "No MSG" or "No Added MSG" to be misleading if the food contains ingredients that are sources of free glutamates, such as hydrolyzed protein.

In 1993, FDA proposed adding the phrase "(contains glutamate)" to the common or usual names of certain protein hydrolysates that contain substantial amounts of glutamate. For example, if the proposal were adopted, hydrolyzed soy protein would have to be declared on food labels as "hydrolyzed soy protein (contains glutamate)." However, if FDA issues a new proposal, it would probably supersede this 1993 one.

In 1994, FDA received a citizen's petition requesting changes in labeling requirements for foods that contain MSG or related substances. The petition asks for mandatory listing of MSG as an ingredient on labels of manufactured and processed foods that contain manufactured free glutamic acid. It further asks that the amount of free glutamic acid or MSG in such products be stated on the label, along with a warning that MSG may be harmful to certain groups of people. FDA has not yet taken action on the petition.
I'd just be careful about very young kids getting additional MSG either in their food or breastmilk.

[LukeA]

Did you know that there is naturally lots of monosodium glutamate in certain vegetables and fruit? Two worth noting are celery and tomatoes.

[LC_Dave]

Did you know that there is naturally lots of monosodium glutamate in certain vegetables and fruit? Two worth noting are celery and tomatoes.

ARRGGHH! Don't say tomatoes!

DOH!

[Frogbreath]

Did you know that there is naturally lots of monosodium glutamate in certain vegetables and fruit? Two worth noting are celery and tomatoes.

You mean it's just naturally in the tomato/celery?

[Nancy LC]

Yes, it is found in nature. Funny though, I don't ever feel like compulsively overeating celery or tomatoes.

[refmls]

If MSG was causing obesity, it seems to me that the traditional (note I said traditional) Chinese diet would have caused much obesity in previous generations, because many, if not most, savory Chinese dishes have MSG added because they like the "umami" flavor. I can't taste it, except as slightly salty, but my daughter (whose dad is part native american) says it is a very distinct flavor.

[Nancy LC]

I thought it was only when Chinese cuisine hit America that the additional MSG was added.

[refmls]

This link tells the history of MSG use in Japanese and Chinese food. Apparently it was origninally used as a naturally occurring substance in seaweed. It was indentified and patented as MSG in the early 1900s.

http://chinesefood.about.com/od/healthconcerns/p/MSG.htm

While its use is spreading, I still think it may be only a minor factor in obesity. HFCS is the ingredient I consider to be the most damaging.

[Nancy LC]

The link you posted sounds like it is only used in chinese restaurants. I doubt even the chinese eat it often enough to get fat off it.

But we put it in everything, chips, and all those starchy foods we eat compulsively (or at least I do, if I get started). They're starting to call it other things now so it is hard to indentify, like hydrolgolized yeast extract.