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Letter to the Editor of the journal Obesity
No! MSG consumption is not healthy.
With their excellent demonstration that monosodium glutamate intake is associated with increased risk of overweight, He et al. noted that in contrast to evidence they had reviewed, the US Food and Drug Administration (FDA) has concluded that monosodium glutamate is a safe food ingredient for the general population. They asked, but did not answer the question: Is monosodium glutamate consumption healthy(1)?
Animal studies dating from the 1970s demonstrated that monosodium glutamate can induce hypothalamic lesions followed by neuroendocrine disorders, including obesity (2); and identical hypothalamic lesions can be induced by hydrolyzed protein products (3).
That early research was followed by admonitions from neuroscientists that use of monosodium glutamate in food, especially food fed to the very young, was inappropriate (4). In response, industry established the International Glutamate Technical Committee (IGTC); recruited researchers and medical schools to do studies from which they concluded there was no evidence that monosodium glutamate was anything but safe; infiltrated the Institute for Food Technologists, the FDA, and the American Medical Association; launched a public relations campaign that ignored sound scientific evidence; and perpetuated the myth that the safety/toxicity of monosodium glutamate is controversial (5).
Monosodium glutamate has never been shown to be safe for human consumption. It was grandfathered onto the generally regarded as safe (GRAS) list when the list was created in 1958.
The designation controversial is based on industry-sponsored studies wherein researchers failed to find a significant difference between subjects treated with monosodium glutamate and subjects treated with a so-called placebo. Neurotoxicity studies did not follow protocols used by independent neuroscientists (6). Epidemiological studies failed to consider all adverse reactions now recognized as reactions to monosodium glutamate (7). Human studies used a variety of devices, including lacing alleged placebos with neurotoxic amino acids found in ingredients other than monosodium glutamate, which precluded finding a difference between monosodium glutamate treatment and placebo in double-blind studies (8).
The FDA appears to cooperate with industry in promoting the safety of monosodium glutamate. IGTC Chairman Andrew G. Ebert has served on the FDA Food Advisory Committee. The FDA has reviewed and approved IGTC protocols for evaluating the safety of monosodium glutamate. FDA-sponsored studies to confirm the safety of monosodium glutamate have impaneled friends of the glutamate industry and/or have restricted review to material selected and delivered by the IGTC; and more than one study done for the FDA by the Federation of American Societies for Experimental Biology (FASEB) has been returned to FASEB for clarification when the industry was not pleased with its outcome (5).
The consensus meeting mentioned by He et al. as demonstrating controversy has been criticized for failure to disclose conflicts of interests of participants (9). One participant, John Fernstrom, has been openly promoting the goals of the glutamate industry for years (10).
There really is no controversy. There is no need for further
study. Monosodium glutamate consumption places humans at risk.
1. He K, Zhao L, Daviglus ML, Dyer AF, Van Horn L, Garside D, Zhu L, Guo D, Wu Y, Zhou B, Stamler J. Association of monosodium glutamate intake with overweight in Chinese adults: the INTERMAP study. Obesity 2008; 16: 1875-1880.
2. Olney JW. Brain lesions, obesity, and other disturbances in mice treated with monosodium glutamate. Science 1969; 164: 719-721.
3. Olney JW, Ho OL, Rhee V. Brain-damaging potential of protein hydrolysates. N Engl J Med 1973; 289: 391-395.
4. Olney JW. Excitatory neurotoxins as food additives: an evaluation of risk. Neurotoxicology 1980; 2: 163-192.
5. Samuels A. The toxicity/safety of processed free glutamic acid (MSG): a study in suppression of information. Accountability in Research 1999; 6: 259-310.
6. Nemeroff CB. Monosodium glutamate-induced
neurotoxicity: review of the literature and call for further research. In:
Miller SA (ed). Nutrition & Behavior. The Franklin Institute Press,
Philadelphia, 1981, pp 177-211.
7. Kerr GR, Wu-Lee M, El-Lozy M, McGandy R, Stare F. Food-symptomatology questionnaires: risks of demand-bias questions and population-biased surveys. In: Filer LJ, Jr., Garattini S, Kare MR, Reynolds WA, Wurtman RJ (eds). Glutamic Acid: Advances in Biochemistry and Physiology, Raven Press, New York, 1979, pp 375-387.
8. Samuels A. Letter to the Editor. Monosodium L glutamate: A double blind study and review. Fd Chem Toxic 1995; 33: 69-78.
9. Pasqualotto AC. Letter to the Editor: Conflict of interests and consensus meetings. Eur J Clin Nutr 2007; advanced online publication, 12 September 2007; doi:10.1038/sj.ejcn.1602909
10. Sved AF, Fernstrom JD. Effects of glutamate
administration on pituitary function. In: Filer LJ, Jr., Garattini S, Kare MR, Reynolds
WA, Wurtman RJ (eds). Glutamic Acid: Advances in
Biochemistry and Physiology, Raven Press, New York, 1979, pp 277-285.
AUTHOR: A Samuels
AFFILIATIONS: The Truth in Labeling Campaign
DISCLOSURE: The author declares receiving no financial support related to this paper and having no conflict of interest.
This work was unsupported.
SUBMITTED FOR PUBLICATION to the journal Obesity: August 26, 2008
REJECTED: November 5, 2008
EDITORS COMMENT: "...after careful consideration, we were not able to assign it a high enough priority score for peer review or publication in Obesity. Of the many factors we consider in manuscripts, whether the data contribute new information to the field is a key consideration."