Adakah MSG Selamat ?
Kathleen
Holton is a
professor in the School of Education, Teaching and Health and the Center for
Behavioral Neuroscience at American University in Washington, D.C. Her
research examines the negative effects of food additives on neurological
symptoms, as well as the positive, protective effects of certain micronutrients
on the brain. She is working on a book about how people can avoid consuming
food additives and test themselves for sensitivity. She contributed this
article to Live Science's Expert
Voices: Op-Ed & Insights.
A recent video from the
American Chemical Society purporting to debunk myths about the food additive
monosodium glutamate (MSG) led to a slew of news stories — but that
coverage failed to recognize that a subset of the population should avoid MSG.
The video contains
two misleading facts. The first suggests MSG is considered
"Generally Recognized as Safe," or GRAS. The GRAS label for
additives gives the appearance of safety; yet the term GRAS was simply given to food
additives that were in use when the Food Additives Amendment of 1958 was
established. The label effectively
"grandfathered in" the additives so they could bypass premarket
approval by the FDA (i.e., safety testing). Secondly, the video states that
free glutamate occurs naturally in some foods. This is true; however, it does
not mean that MSG is safe for everyone. People who are sensitive to MSG
must also avoid
foods with high amounts of naturally occurring free glutamate, such as soy
sauce and Parmesan cheese.
How MSG works
MSG
is a flavor enhancer that has been used in
processed foods in the United States since after World War II. Though many
associate MSG with Chinese food, people are more likely to encounter MSG in
foods like soup, broth, chips, snacks, sauces, salad dressings and seasoning
packets. The active part of MSG, which imparts its "umami" flavor,
comes from the glutamate portion of the compound. Glutamate is an amino acid commonly
found in the diet in bound form (connected to other amino acids to form a full
protein, like meat) and free form (where glutamate is no longer bound to a
protein). It is this free form of glutamate (like that found in MSG) which has
the ability to act as a flavor enhancer in food by exciting the neurons in your
tongue.
Glutamate can always be considered a "natural
flavor" because it is produced by dissociating a naturally occurring
protein into its individual amino acids. Additives containing free
glutamate are created by simply disrupting any protein's structure through
hydrolyzation, which frees glutamate (and other amino acids), allowing
glutamate to enhance the flavor of food by stimulating the neurons on your
tongue.
Who needs
to avoid MSG?
As researchers, we don't yet know what percentage of the
population is sensitive to MSG. But we do know enough to confirm that the amino
acid glutamate, when in its free form (i.e., when it is not bound to a full
protein like meat) causes negative reactions in certain people. An individual's
reaction to MSG is not limited to Chinese Restaurant Syndrome (CRS), which is
characterized by symptoms like headache, sweating, rapid heartbeat and
tightness in the chest. These symptoms usually occur within minutes of eating
the compound, often while the diner is still in the restaurant.
In my
research on the effects of MSG in
individuals with irritable bowel syndrome and the chronic pain condition
fibromyalgia, I observed headache (including migraine), diarrhea,
gastrointestinal pain and bloating, extreme fatigue, muscle pain and cognitive
dysfunction — all of which improved when subjects were put on a diet low in
free glutamate, and which returned with re-introduction of MSG. (This was a
double-blind, placebo-controlled study). In contrast to CRS, symptoms in
fibromyalgia patients tend to begin somewhat later, hours after
ingestion, making it more difficult for these people to identify the food-related
trigger.
Other researchers are studying the potential effects of
MSG on conditions like migraine, temporomandibular joint disorder (TMD/TMJ),
obesity and Type 2 diabetes. Researchers from the University of North Carolina
at Chapel Hill recently found an association between high consumption of MSG
and the prevalence of overweight adults in China. Understandably, the glutamate
industry is hotly contesting these and other findings related to MSG and
obesity. Consumers should know that the glutamate industry funded the
majority of studies "proving" the safety of MSG. Independent
scientists have not always agreed with those findings.
Avoiding glutamate
In addition to MSG,
free glutamate can also be found in other food additives, including any
hydrolyzed protein, protein isolate, protein extract and autolyzed yeast
extract, just to name a few. Food manufacturers can use these additives in a
product, and still label the food as not containing MSG, since the chemical
structure is different. That is, the structure does not contain the sodium part
to form monosodium glutamate.
However, the effect of the free glutamate is the same as that of MSG (both in
its flavor-enhancing ability as well as its ability to cause symptoms in
sensitive individuals).
Glutamate is not only an amino acid in the diet, it is
also an important neurotransmitter essential for the optimal functioning of our
nervous systems. However, too much of this chemical can cause things in our
bodies to go awry. It is well established that high amounts of glutamate can
cause "excitotoxicity," where neurons get over-excited to the point
that they die.
For example, because of the consistent research on the
excitotoxic effects of MSG on the brains of young animals in the 1960s,
researchers testified before the U.S. Congress about the danger of using MSG in
baby food. As a result, MSG was voluntarily removed from baby foods in
1969.
The million-dollar question is: Does everyone react to
these additives? No, some people can consume relatively high amounts of free
glutamate without any symptoms. However, research shows that a subset of
the population is sensitive and can benefit from avoiding MSG (and other
sources of free glutamate) in food.
If a person is suffering from unexplained symptoms like
headache, bowel disturbance, fatigue, cognitive dysfunction, or pain that lacks
a structural explanation, they may want to try avoiding free glutamate in all
its forms. The only way to test for sensitivity is by avoiding excess free
glutamate for a period ranging from two weeks to a month. One can do this by
eating whole, non-processed foods, using whole herbs and spices, making
marinades and salad dressings from scratch, and avoiding foods which naturally
have higher amounts of free glutamate, like soy sauce, fish sauces, Parmesan
and other aged cheeses, and large amounts of tomato sauce.
The moral of the story is simple: Blanket statements like
"MSG isn't bad for you" are misguided — they give a false perception
of safety to a compound that not everyone should be consuming.
Follow all of the Expert Voices issues and debates — and become
part of the discussion — on Facebook, Twitter and Google+. The views expressed are those
of the author and do not necessarily reflect the views of the publisher. This
version of the article was originally published on Live Science.
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