MSG and Weight Gain

The Body Mass Index (BMI) is a measure of the relative percentages of fat and muscle mass in the human body, based on a person’s weight and height, used to assess obesity. This barometer was used by researchers to determine the effect of the food additive, monosodium glutamate (MSG), on weight over a period of time. It was learned that those persons who consume MSG regularly experience changes in the part of the brain that controls appetite, thus having an influence on energy balance and consequent weight gain.

When researcher, Ka He, and his colleagues at the University of North Carolina began to look for a relationship between monosodium glutamate and weight gain, they hypothesized that it would be a positive one.  As a design element of the study, “…overweight was defined as a body mass index ≥ 25…based on World Health Organization recommendations for Asian populations.”  With an average MSG intake of 2.2 grams a day, and a five-year follow-up, the study population demonstrated that “MSG consumption was positively, longitudinally associated with overweight development…”

The better it tastes, the more we’ll eat.  That seems logical.  Most Americans eat so fast that their brains don’t have enough time to process the information that says they’re full.  Since that lag time is about twenty minutes, we should take at least that much time to eat.  But the school cafeteria, the incessant phone calls, the pressures of the job, and other lifestyle components disallow that.  Combine any of these facets of life with food additives that enhance flavor, and start looking for a longer belt.

Leptin is a hormone that plays an important role in energy intake and expenditure, and it tells us when to stop eating…if it works the right way.  It’s made by fat cells, oddly enough, but can also come from other parts of the body, such as the bones, stomach, and liver.  It acts on parts of the brain’s hypothalamus, where it inhibits appetite. If leptin is not appropriately received and taken up by the hypothalamus, appetite fails to shut off and food intake is uncontrolled.  Where does MSG fit into this picture?  It seems to be able to induce hypothalamic lesions and ensuing leptin resistance (He, et al. 2008).  The stage is now set for weight gain.

Glutamate is the major excitatory transmitter in the brain, meaning that it makes things happen, especially in cognition, memory and learning.  It also affects brain development, cellular survival and the manufacture of synapses.  Too much glutamate, though, can raise serious concerns because its excitatory nature becomes intensified by virtue of its accumulation, allowing excess calcium to enter a nerve cell and damage it beyond repair.  This is what happens in the hypothalamus.

Glutamate, sometimes as glutamic acid, is responsible for the tantalizing flavors of poultry, some fishes, and eggs, among other foods.  Its salt, MSG, was introduced to the United States after WW II as “Accent” flavor enhancer.  It can be made by the fermentation of beets, sugar cane, or molasses.  People began to experience adverse reactions to MSG after eating Chinese food prepared with it, thereby coining the expression “Chinese Restaurant Syndrome.”  Sensitivity to monosodium glutamate may present with headaches, asthmatic symptoms, hyperactivity (especially in children), and obesity.  Frequency of such responses is low, but if it happens in your family, it’s high enough to merit attention.

We all know that the world revolves around the dollar bill and the ball point pen, the latter often employed to guarantee the former.  As long as clandestine groups can get away with something, they’ll persist.  And so it is with MSG.  It has more disguises than Artemus Gordon and Sherlock Holmes combined.  Here are a couple handfuls of MSG aliases:  glutamic acid, monopotassium glutamate, magnesium, glutamate, monoammonium glutamate, yeast extract, hydrolyzed anything, calcium or sodium caseinate, yeast nutrient, gelatin, textured protein, soy protein isolate, soyprotein concentrate, whey protein, ajinomoto.

These ingredients often contain glutamic acid:  carrageenan, bouillon, stock, maltodextrin, barley malt, protease, malt extract, soy sauce, and any protein that is fortified or fermented.  Additionally, these work with MSG to further enhance flavor:  Disodium 5’-guanylate; Disodium 5’-inositate; and Disodium 5’-ribonucleotides.  Wherever these three abide, it’s almost guaranteed that MSG is a companion.

Individual amino acids are not generally listed on the ingredients labels of food or health care products.  Binders and fillers may or may not contain MSG.  Believe it or not, MSG may also appear in cosmetics, including shampoos, soaps and hair conditioners.  If the words “hydrolyzed,” “amino acids,” or “protein” appear on the label, MSG could be in it.  Live virus vaccines may also have it.  Even though reactions to MSG are dose-dependent, you could react to a very small amount all of a sudden, when you never did so before.  Yes, MSG is natural, but so is arsenic.  To most of us, MSG does not cause problems.  MSG might make you want to eat more.  It might affect the state of your hypothalamus.  On the other hand, it’s not likely to make you wash your hair more often.  Is it?

Am J Clin Nutr. 2011 Jun;93(6):1328-36. Epub 2011 Apr 6. Consumption of monosodium glutamate in relation to incidence of overweight in Chinese adults: China Health and Nutrition Survey (CHNS). He K, Du S, Xun P, Sharma S, Wang H, Zhai F, Popkin B Departments of Nutrition and Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC.

Acta Physiol Hung. 2011 Jun;98(2):177-88. Monosodium glutamate versus diet induced obesity in pregnant rats and their offspring. Afifi MM, Abbas AM. Department of Biochemistry, Zagazig University, Zagazig, Egypt. Abstract

Am J Clin Nutr. 2011 Jun;93(6):1328-36. Epub 2011 Apr 6. Consumption of monosodium glutamate in relation to incidence of overweight in Chinese adults: China Health and Nutrition Survey (CHNS). He K, Du S, Xun P, Sharma S, Wang H, Zhai F, Popkin B.

Nutrition. 2005 Jun;21(6):749-55. Monosodium glutamate in standard and high-fiber diets: metabolic syndrome and oxidative stress in rats. Diniz YS, Faine LA, Galhardi CM, Rodrigues HG, Ebaid GX, Burneiko RC, Cicogna AC, Novelli EL. Department of Clinical Cardiology, Faculty of Medicine, University of São Paulo State, Botucatu, Brazil.

Mol Pharmacol. 1989 Jul;36(1):106-12. Delayed increase of Ca2+ influx elicited by glutamate: role in neuronal death. Manev H, Favaron M, Guidotti A, Costa E. Fidia-Georgetown Institute for the Neurosciences, Georgetown 4niversity, Washington, DC 20007.

Cell Calcium. 2003 Feb;33(2):69-81. Calcium influx constitutes the ionic basis for the maintenance of glutamate-induced extended neuronal depolarization associated with hippocampal neuronal death. Limbrick DD Jr, Sombati S, DeLorenzo RJ.