MSG-myth versus science

December 31, 2012 Filed in: Nutrition | Obesity

msg bagFood additives are one of the most passionate issues amongst people who eat (which would be everyone). High fructose corn syrup. Salt. Sugar. Trans fats. Polysorbate 80. Some of the angst caused by these additives is that they have scary chemical names. Obviously the “low fructose corn syrup” has got to be better? Right?

But the one food additive that will bring fear to the minds of all consumers of food is MSG. How many times have you been to a Chinese restaurant where they put up signs with NO MSG ADDED. Just so you know, unless that restaurant isn’t using soy sauce (one of the major components of nearly all Chinese food flavorings), the amount of MSG in your Kung Pao Chicken is still quite high, because that soy sauce has more MSG in it than could possibly be added by a shaker of MSG.

Background

MSG has no taste by itself, but it is used by many cooks as a flavor enhancer, improving and enhancing the flavor of almost any food at lower concentrations. The taste that is enhanced by MSG is different than the standard sour, sweet, bitter and salt flavors–it is called “umami,” which also is enhanced by substances like soy sauce. It’s the savory flavor that one finds that is different from the older “four tastes” that chefs used to consider. The flavor enhancing quality of MSG is not well understood, but it’s possible that humans evolved the pleasurable taste of umami as a result of natural selection favoring those who enjoy eating high quality protein foods.  

MSG has been used as a flavor enhancer for several thousand years. It is one of the key components of many Asian cuisines, especially Japanese who have extracted MSG from kelp for centuries. The Romans used a sauce called garum, made from fermented fish, that was used instead of more expensive salt. In fact, MSG can be used to mask bad flavors, such as spoiled meat, just like salt. 

Myth

The myth of MSG probably started with personal anecdotes after eating Chinese food. A 1969 article in Science claimed there was a dose-response relationship between Chinese food and the Chinese Restaurant Syndrome (CRS).  But the study did not isolate MSG as the cause, and was not blinded (which would be nearly impossible if were to determine if the cause was the food rather than the ingredients).  Unfortunately, the study has never been repeated, so it’s impossible to determine if it provides evidence that Chinese food does anything, let alone MSG.

Joe Mercola, one of the leading purveyors of nonsense science and medicine, calls MSG “the silent killer lurking in your kitchen cabinets.” Oh my. His claims are based on a belief that MSG is an excitotoxin, which causes a pathological process by which nerve cells are damaged and killed by excessive stimulation by neurotransmitters. This pseudoscience is promoted by  Dr. Russell Blaylock, a board-certified neurosurgeon and author of “Excitotoxins: The Taste that Kills.” Setting aside the Appeal to Authority (a board certified neurosurgeon may not have any actual knowledge of neurochemistry), a book isn’t necessarily a high quality source.

Mercola pushes a belief that MSG overexcites your nerve cells to the “point of damage or death, causing brain damage to varying degrees — and potentially even triggering or worsening learning disabilities, Alzheimer’s disease, Parkinson’s disease, Lou Gehrig’s disease and more.” Oh my!

But Mercola doesn’t stop there. He also believes that MSG causes obesity, eye damage, headaches, fatigue, disorientation, depression, and a whole host of other maladies. And he states that up to 40% of the US population may be impacted by MSG. OH MY!

Science

First, what exactly is MSG. This is the point that makes many scientists laugh, because MSG is the sodium salt of glutamic acid, an amino acid which is the building block of proteins. You get glutamic acid from almost every food you eat from grains to meat. Some grain proteins have over 30% by weight glutamic acid. Since glutamic acid doesn’t exist except in the presence of water, it precipitates with sodium or other cations (potassium, lithium, and others).  Hence, the “monosodium” part of MSG.  

Here’s the actual science behind glutamates (you can pass this over, if your eyes glaze over). When glutamic acid or one of its salts is dissolved in aqueous solutions, a pH-dependent instantaneous chemical equilibrium of the amino acid’s ionized forms, including zwitterionic forms, will result. These forms are called glutamates. Salts exist only in a dry and crystallized form. The form ultimately responsible for the taste is the glutamate ion, and the form of glutamic acid at the time of the addition is not important. However, crystalline glutamic acid salts such as monosodium glutamate dissolve much better and faster than crystalline glutamic acid, a property important for use as a flavor enhancer.

Glutamic acid, one of the amino acids upon which every single protein is built in the human body, is chemically indistinguishable from the acid salt, MSG. Once you ingest MSG, it dissociates into sodium and the glutamate, which will be absorbed and utilized by the body. Glutamic acid does not suddenly change properties when in salt form. Once it’s consumed, the glutamate separates from the sodium, and binds with hydrogen to become an acid again. The sodium is either utilized by the body or excreted through the kidneys.  It’s a simple physiological process, no mystery at all.

The body produces glutamate (or glutamic acid more properly) during various cellular processes, including the citric acid cycle, or Kreb’s cycle, which is a complex metabolic system fundamental to how the cell builds proteins and provides energy. Glutamate is also a key compound in eliminating and controlling the waste nitrogen in the body (which is created by cells in the form of urea). It is also a neurotransmitter, used by nerve cells to transmit certain types of information, and is a critical substance in cognitive functions in memory and learning.  In other words, glutamate is very important to your life.  Without it, you will probably die. Or at least not be able to think.

So if you eat a lot of glutamate in your food, and your body synthesizes glutamate in substantial quantities, what is bad about MSG. Well, there’s a couple of issues that might happen. MSG does have a sodium, but it’s actually less by weight than an equivalent amount of table salt. Interestingly, in a 1984 Journal of Food Science article, MSG may actually be useful in reducing sodium consumption while not compromising taste (salt is critical to taste of many savory foods).  

But is there any evidence that MSG is dangerous to humans?  In a word, no.

These review articles, which are meta-analyses of a large number of primary research articles, along with clinical trials, just don’t support the myth that MSG has an effect on anyone. There might be a small subpopulation of people who are sensitive to MSG, but even that has minimal support in scientific evidence.

It is possible that Chinese food itself causes CRS. The food is saltier. It is filling. It can be high in carbohydrates and oils. In other words, other substances within the food may have the same exact effect as what is claimed by MSG alone. Funny thing is that soy sauce is higher in free glutamate (as discussed above, the form of MSG in solution) than what is used by most cooks. So are tomatoes. So are dozens of other foods.

In fact, according to a report by Food Standards Australia New Zealand, a typical Chinese restaurant meal will have between 10-1500 mg glutamate per 100 g food. Soy sauce has 400-1200 mg/100g. Vegemite (for my Australian readers) has about 1400 mg/100g. Parmesan cheese has around 1200 mg/100g. Tomatoes have around 200 mg/100g. In other words, your typical Italian meal (with tomato sauce and Parmesan) may provide more glutamate than your typical Chinese meal. 

Almost everyone you hear who claim an MSG sensitivity do not base that on anything but their personal experience. An anecdote. They remember the one time that they might have had MSG, but forget all the times they felt fine after having sushi with soy sauce. Or a BBQ sauce that contains soy sauce and tomato sauce.  

MSG is perfectly safe.  Go have a spoonful. Or put it on your food, because it does make it tastier.

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Comments (9)

9 Responses to “MSG-myth versus science”

  1. Kevin Richter says:
    June 6, 2013 at 12:34

    Thank you for your rational analysis. However, I'm going to respectfully disagree with your conclusion as a skeptic from the other side. You easily dismiss all personal experience as mere anecdote. If my personal experience includes critical thinking, reason, and evidence based, repeatable testing (including blinds), can it be so easily dismissed?

    You could line up as many studies as you like showing the safety of peanuts by testing on individuals without nut allergies. The personal experience of those allergic to peanuts has been tested and the (sometimes fatal) immune response mechanisms are well understood. The fact that scientists still can't identify what causes a peanut allergy doesn't degrade the reality of the condition.

    Unlike some who consume soy sauce with no symptoms, my personal experience includes years of going through elimination diets and "blind" discovery of hidden additives and ingredients. My personal sensitivity goes beyond blatant MSG into other free glutamate containing substances. Feed me ice cream and I can likely tell you if it contains Carrageenan or not. I eat cookies with and without Annatto and only those with Annatto bother me.

    I am open to the idea that MSG is "safe" and harmless for most people. However, personal experience has forced me to be skeptical of existing research and studies. For example, the study you reference (published in Journal of Nutrition in April 2000) includes the following notes on test procedure, "Each subject randomly received three times capsules containing 5 g MSG and three times capsules containing placebo (5 g sucrose) during a cereal breakfast consisting of Frosted Flakes" Kellogg's web site for it's Frosted Flakes cereal lists ingredients of "Milled corn, sugar, contains 2% or less of malt flavoring, salt, BHT for freshness." If MSG in the form of malt flavoring is given along with the placebo, how can one scientifically establish that MSG has no effect?

    Any subject with a significant response to Frosted Flakes would have been excluded from the study. By these methods, they performed a test to determine MSG sensitivity by first (inadvertently) excluding all subjects sensitive to MSG and then demonstrating non-sensitive subjects did not show a response to MSG. I believe this qualifies as an error in methodology.

    Doesn't including other free glutamate containing substances (such as gelatin) in placebo or control group protocols necessarily mask any response? If both the test and control group in a double blind receive MSG, then one could legitimately observe "no discernible difference" in symptoms between the groups while having proved nothing.

    My negative personal experiences with MSG have caused me to skeptically analyze existing research. Thusfar I find inadequate scientific rigor to definitively state MSG does not cause adverse reactions. Do you disagree?

    • Michael Simpson says:
      June 9, 2013 at 16:14

      We're going to have to disabuse you, first of all, of improperly using "skeptic." Scientific skepticism values evidence over anything else, and is not, as a lot of people believe, just a curmudgeonly need to contradict commonly held beliefs based on wanting to be cranky.

      Anecdote is "mere" and it is not evidence. There are lots of reasons for dismissing anecdote, everything from confirmation bias to out right lies. That's why science is so cool, you blind and randomize to eliminate bias from anecdotes.

      Your peanut story is cute, but it is a strawman, and irrelevant. Peanuts cause allergies from complex protein structures. MSG is simply an amino acid that is common in all proteins, in your body, etc. In most people, they break down complex proteins into simple amino acids, including glutamic acid.

      You have provide nothing scientific. Your criticism of the article is silly, since there's glutamic acid in ALL foods. That's the point, if you actually understood science. The placebo, which has a baseline of glutamate, as do all foods, showed no difference than actually consuming MSG. Geez.

      You are not a skeptic. You just want to believe in what you want to believe, evidence be damned. That's fine. You can do that all day long. But it isn't science. And it most certainly is not skepticism.

    • Kevin Richter says:
      June 10, 2013 at 03:50

      Michael, the blog author's definition of Skepticism is "a process of critical thinking, reason, and evidence to determine the validity of an hypothesis."

      Consider what an elimination diet is – removal of all or a large set of foods for a period of time to cleanse the body. Individual foods are then added and symptoms monitored for 4 days. If no symptoms, another food can be added. If symptoms appear, go back to a baseline for 4 days to a week before challenging another food. Continue for 2-6 months. Records were kept of all foods eaten and symptoms observed by two test subjects (my wife and I) and two controls (our children). I'll concede that testing in our household was not documented and submitted to a peer reviewed journal, but it does not make our methods less scientific.

      Repeated studies over a period of over 7 years in our home have included blinds (restaurant food and dishes prepared by others). Results in my personal study all seem to correlate and corroborate the hypothesis that my body reacts as to a toxin when some threshold of ingested free glutamates is exceeded. My current conclusions meet the definition of a scientific hypothesis or working hypothesis (a PROPOSED explanation). Determining actual etiology of symptoms would require further study.

      While glutamates are found in nearly all foods, most glutamates are chemically bound to other proteins. These are absorbed and processed differently than free glutamates. Only foods containing FREE glutamate ions trigger the taste response known as umami.

      For the moment, consider my claim or assertion to be that ingestion of free glutamates such as manufactured MSG (over 99.6% free glutamic ions) can and do have measurable, biochemical impact on the human body.

      In support of this claim, I offer two studies which both indicate consumption of food supplemented with MSG results in a sharp increase in glutamate or amino acid levels in blood plasma. These spikes do NOT occur when a "normal" meal (without added free glutamates) is consumed. Food does not spike levels in plasma. Food with MSG spikes glutamate levels in blood plasma. These are not opinions or anecdotes, but evidence of a measured impact of manufactured MSG which differs from consumption of food without added MSG.

      "Plasma glutamate concentrations were not significantly increased over baseline (3.69± 1.08 Mmol/dl) when no added MSG was present. However, mean peak plasma glutamate levels increased proportional to dose when MSG was added (10.2 ± 2.00 and 17.0 ± 8.06 smol/dl at 25 and 50 mg/kg body weight respectively)."
      Am J Clin Nutr August 1985 vol. 42 no. 2 220-225 (http://www.ncbi.nlm.nih.gov/pubmed/2862786)

      "An interesting finding of the present study was the transient rise in plasma concentrations of many amino acids when subjects ingested the MSG-supplemented meal. This effect concerned in particular branched-chain amino acids, with significant 20–25% increases of circulating concentrations of leucine and isoleucine at 1 and 2 h after the meal.
      …
      In conclusion, we show that MSG supplementation at nutritional doses elicits in healthy humans a postprandial gastric distension and an elevation of several amino acid plasma concentrations that are possibly linked."
      AJP – GI January 1, 2011 vol. 300 no. 1 G137-G145 (http://ajpgi.physiology.org/content/300/1/G137.full)

      I claim The Skeptical Raptor's scientific analysis of MSG's impact on the human body is incomplete. I propose that processed and fermented foods which concentrate or create free glutamate ions have a more pronounced impact upon the body than other naturally occurring glutamates.

      I further claim that you, Michael, are endeavoring to assert the Raptor is right based predominately on your preconceived conclusions rather than upon an analysis of evidence. Did you take the time to review the study I criticized? I would challenge you to review the materials yourself. The least you could do is question why I or anyone else could assert there are free glutamates in malt flavoring.

      My original post was a claim that at least one of the references cited by the Raptor contains flawed methodology. This would place doubt upon the conclusions drawn by the study as well as the position the Raptor takes that MSG's impact upon the body is merely myth.

      I do NOT claim here any proven link between MSG and CRS or any other disease or condition. My claim is that to dismiss all possibility of a link using only the cited (flawed) sources and a position that glutamate is natural and pervasive is a rejection of evidence based on a personal desire for a particular conclusion.

      I may be wrong about MSG. I have a hypothesis but am open to other causes for observed symptoms. What I will state without reservation is my efforts to evaluate the evidence based on scientific principles leave me skeptical of the Raptor's conclusions regarding MSG.

    • Michael Simpson says:
      June 10, 2013 at 20:04

      Cutting through your longwinded reply, let me continue to disabuse you of some of your delusions.

      First, you don't get skepticism at all. It values evidence, and you plainly don't. You have cherry picked and confirmed your bias all day long, and you won't hear any of it.

      I dismiss the claim for one major reason. You need to provide evidence that a rise in glutamate concentrations, consumption of glutamate, or snorting glutamate causes ANY change to any physiological process. You're making a claim. Provide evidence, or you're no different than most, if not all, pseudoscience pushing individuals.

      If you have a hypothesis, then I strongly suggest you get your Ph.D., get work in a world class laboratory, and provide evidence. I'll eat my shoe laced with MSG if you even get to the first step of that process.

    • Michael Simpson says:
      June 10, 2013 at 20:06

      Kevin Richter By the way. You're misusing "hypothesis". A hypothesis is something that is based on observation. Have you had long-term observations of any effect from MSG?

      Oh, and you need to read some of my other articles regarding the quality of evidence supporting a hypothesis. They vary in quality. I only use the highest quality SECONDARY research in support of my hypothesis, that MSG does nothing. Moreover, when I write, I seek out all secondary research. Funny thing, none exists supporting the nullification of my hypothesis. Amusing that.

  2. Rolinda Gloria says:
    April 4, 2013 at 04:50

    very informative. thank you very much.

  3. Ian Hollenbeck says:
    February 21, 2013 at 08:01

    I'm so glad you acknowledges that MSG CAN NOT pass the BLOOD BRAIN BARRIER, Based on my appearance and where I work people come up to me all the time with qualms about MSG, aspartame, and are surprised to find I don't share their opinions, I''ll mark this article for future reference :)

  4. Kathy Hennessy says:
    December 31, 2012 at 17:56

    that was a good read :)

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