Anecdotal and lab evidence provide ample reasons to avoid the controversial food additive, which hides under many names
by Craig Weatherby
We refuse to use synthetic additives in Vital Choice foods (For one reason why, see our accompanying article, “Food Additives May Cause Hyperactivity”).
But some presumably “natural” food ingredients and additives aren't quite what they seem.
For example, if you look at the ingredient list on one famous brand of canned tuna, you will notice that it includes “vegetable broth.” Sounds natural enough, right?
In fact, “vegetable broth” is just one of many non-synthetic food ingredients or additives that, deliberately and disingenuously, contain high levels of monosodium glutamate (MSG).
The motivation to add MSG is obvious, since it heightens the tastes already imparted by natural foods, thereby increasing consumption and repeat sales.
And the motivation to hide MSG under other names—namely, consumers' vague discomfort with foods containing added “chemicals”—is equally obvious.
Glutamate (glutamic acid) is an essential amino acid, and as such it is one of the building blocks of proteins found in many natural foods such as parmesan cheese, tomatoes, spinach, mushrooms, and seaweed.
Thus, glutamate is perfectly natural.
But the glutamate in whole foods is bound up in their proteins, and is released incompletely and slowly.
In contrast, the “free” glutamate in MSG gets split from its bond with sodium very rapidly, sending much greater amounts into the bloodstream.
And as we will explain, it is the rapid release of relatively large amounts of glutamate from MSG that may present real, albeit uncertain risks.
The story of MSGSeveral years before the outbreak of WW I, Japanese chemist Kikunae Ikeda began wondering why most Japanese cooks seasoned soups with a seaweed called kombu. In 1908, he identified kombu's natural flavor enhancing constituent as the sodium salt of glutamic acid, or monosodium glutamate (MSG).
By the mid-1930s, synthetic MSG had become a major additive in Asian foods. MSG landed on these shores after World War II, and soon found its way into many processed and restaurant foods.
MSG is unique in that it does not impart a flavor, per se, but instead stimulates neural pathways associated with taste, thereby heightening the intensity of the flavors created by foods.
MSG has this effect because glutamate is a key neurotransmitter, for which our cell
surfaces have special receptors.
The problem is that over-stimulation of glutamate receptors generates free radicals, which damage nerve and brain cells.
Neuroscience even has a special name—excitotoxins—for chemicals that over-stimulate glutamate receptors, which include MSG and Aspartame.
This is how the authors of a recent study described the dangers of over-stimulating people's glutamate receptors (Lipton SA et al 2007):
- “Excitotoxicity, defined as over-stimulation of glutamate receptors, has been implicated in a final common pathway contributing to neuronal injury and death in a wide range of acute and chronic neurological disorders, ranging from Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), multiple sclerosis, and Alzheimer's disease (AD) to stroke and trauma.
- “Excitotoxic cell death is due, at least in part, to excessive activation of… glutamate receptors, leading to… free radical production... These free radicals can trigger a variety of injurious pathways…”
These authors were not talking about the effects of consuming free glutamate or MSG from foods. In fact, there is little or no evidence that even relatively high intake of glutamate or MSG from foods causes detectable, short-term brain damage in human adults or children.
But given what we know about excitotoxins like MSG, it appears plausible to propose that chronic consumption of free glutamate and/or MSG could promote or exacerbate degenerative neurological diseases such as Parkinson's and Alzheimer's.
What's more, MSG may help make you fat, as it does rodents:
the occurrence of “MSG-obesity” in rodents fed the additive in their chow is well documented (Iwase M et al 1998, 2000; Guimaraes RB 2002).
Chinese Restaurant Syndrome
Short of brain damage, some people experience distinct symptoms—including headaches and tightness in the chest— after ingesting MSG: an uncommon but well-documented condition called Chinese Restaurant Syndrome.
Clinical studies have generally failed to detect any difference in people's reactions to MSG and “placebos”, which, by definition, are supposed to exert no biological effects related to the substance (in this case, MSG) being tested.
However, quite a few trials used placebos that were (suspiciously) unidentified or included Aspartame, which is also considered an excitotoxin and could produce the same effects as MSG, thereby leading the researchers to conclude that MSG is “no different from placebo.”
Some of these studies were conducted or funded by an MSG-industry group called the International Glutamate Technical Committee.
To quote one skeptical researcher: “Placebo-controlled studies of effects of monosodium L-glutamate (MSG) and mixed synthetic food dyes in humans which have led to claims that these additives are safe in general use may be questioned on 3 methodological grounds: both active substance and placebo may be inadequately specified in published reports and potent common food allergens are used as placebos” (Rippere V 1981).
We, too, are skeptical about the assurances that MSG is totally safe, so we keep MSG—in all of its guises—out of our canned Albacore Tuna and all other Vital Choice foods.
- Freeman M. Reconsidering the effects of monosodium glutamate: a literature review. J Am Acad Nurse Pract. 2006 Oct;18(10):482-6. Review.
- Geha RS, Beiser A, Ren C, Patterson R, Greenberger PA, Grammer LC, Ditto AM, Harris KE, Shaughnessy MA, Yarnold PR, Corren J, Saxon A. Review of alleged reaction to monosodium glutamate and outcome of a multicenter double-blind placebo-controlled study. J Nutr. 2000 Apr;130(4S Suppl):1058S-62S. Review.
- Gonzalez-Burgos I, Perez-Vega MI, Beas-Zarate C. Neonatal exposure to monosodium glutamate induces cell death and dendritic hypotrophy in rat prefrontocortical pyramidal neurons. Neurosci Lett. 2001 Jan 12;297(2):69-72.
- Guimaraes RB, Telles MM, Coelho VB, Mori RC, Nascimento CM, Ribeiro EB. Adrenalectomy abolishes the food-induced hypothalamic serotonin release in both normal and monosodium glutamate-obese rats. Brain Res Bull. 2002 Aug 15;58(4):363-9.
- Iwase M, Ichikawa K, Tashiro K, Iino K, Shinohara N, Ibayashi S, Yoshinari M, Fujishima M. Effects of monosodium glutamate-induced obesity in spontaneously hypertensive rats vs. Wistar Kyoto rats: serum leptin and blood flow to brown adipose tissue. Hypertens Res. 2000 Sep;23(5):503-10.
- Iwase M, Yamamoto M, Iino K, Ichikawa K, Shinohara N, Yoshinari M, Fujishima M. Obesity induced by neonatal monosodium glutamate treatment in spontaneously hypertensive rats: an animal model of multiple risk factors. Hypertens Res. 1998 Mar;21(1):1-6.
- Kubo T, Kohira R, Okano T, Ishikawa K. Neonatal glutamate can destroy the hippocampal CA1 structure and impair discrimination learning in rats. Brain Res. 1993 Jul 9;616(1-2):311-4.
- Lipton SA, Gu Z, Nakamura T. Inflammatory mediators leading to protein misfolding and uncompetitive/fast off-rate drug therapy for neurodegenerative disorders. Int Rev Neurobiol. 2007;82:1-27. Review.
- Matute C, Alberdi E, Domercq M, Sanchez-Gomez MV, Perez-Samartin A, Rodriguez-Antiguedad A, Perez-Cerda F. Excitotoxic damage to white matter. J Anat. 2007 Jun;210(6):693-702. Epub 2007 May 15.
- Rausch WD, Liu S, Gille G, Radad K. Neuroprotective effects of ginsenosides. Acta Neurobiol Exp (Wars). 2006;66(4):369-75. Review.
- Rippere V. Placebo-controlled tests of chemical food additives: are they valid? Med Hypotheses. 1981 Jun;7(6):819-23.
- Singh P, Mann KA, Mangat HK, Kaur G. Prolonged glutamate excitotoxicity: effects on mitochondrial antioxidants and antioxidant enzymes. Mol Cell Biochem. 2003 Jan;243(1-2):139-45.
- Smith JD, Terpening CM, Schmidt SO, Gums JG. Relief of fibromyalgia symptoms following discontinuation of dietary excitotoxins. Ann Pharmacother. 2001 Jun;35(6):702-6.
- Symes WL, Gardner JA. The Toxicity of Sodium pyrophosphate administered in Food; with a Note on Toxic Cotton Seed Meal. Biochem J. 1915 Mar;9(1):9-16.
- Walker R, Lupien JR. The safety evaluation of monosodium glutamate. J Nutr. 2000 Apr;130(4S Suppl):1049S-52S. Review.
- Yang WH, Drouin MA, Herbert M, Mao Y, Karsh J. The monosodium glutamate symptom complex: assessment in a double-blind, placebo-controlled, randomized study. J Allergy Clin Immunol. 1997 Jun;99(6 Pt 1):757-62.