|
Is MSG a Serious Public Health Problem?
Good through December 2010
By James J. Kenney, Ph.D., R.D., F.A.C.N.
What is MSG (1)
What is the MSG Symptom Complex? (2)
Is the MSC Associated with Any Physical Symptoms? (2)
MSG and Food Terrorism (3)
Does MSG Cause Allergic Reactions and Asthma? (3)
Does MSG Cause Nerve damage or Alter Hormone Levels? (4)
MSG is High in Sodium So Does It Promote Hypertension? (5)
Salt Is Far More Dangerous Than MSG (5)
Conclusions (6)
References (7)
Back in 1968 a Korean-American physician wrote a letter to
the editor of the New England Journal of Medicine describing an unusual
physiological reaction he often experienced while dining at a Chinese
restaurant, which he dubbed the "Chinese restaurant syndrome."[1]
Dr. Kwok described the symptoms as "numbness at the back of the neck,
gradually radiating to both arms and the back, general weakness and
palpitations." Other anecdotal reports expanded the symptom complex to
include muscle tightness, tingling sensations, headaches and chest pains or
heart palpitations. It became known as the "Chinese restaurant
syndrome". More recently this reaction has been renamed the more politically
correct "MSG symptom complex" (MSC).
Over the past several decades many Americans have become convinced that
MSG is the source of not only this symptom complex but also a wide variety of
other symptoms including some serious illnesses and even death.
MSG is the sodium salt of L-glutamic acid (GLU). GLU is
the most common amino acid found in the human body and a major constituent of
virtually every protein in the human body. It also occurs naturally in every
plant and animal primarily as part of enzymes, structural proteins, etc. Free
GLU is also found in varying amounts in many foods. Fermented soy products,
Parmesan cheese and tomato juice all contain fairly large amounts of free GLU.
Most proteins found in plants and animals contain from 5 to 25% GLU. Life as we
know it would not be possible without glutamate. The average American consumes
at least 5,000 to 10,000 mg of GLU daily even if all the foods and beverages
they consumed had no added MSG. By contrast, the average American consumes only
a few hundred milligrams of glutamate daily as added MSG. MSG is
"generally recognized as safe" by the FDA. A 1995 report by the
Federation of American Societies for Experimental Biology found no convincing
evidence that MSG posed any serious threat to public health.[2]
Nevertheless, MSG is believed by many people to pose a serious threat to their
health and well-being.
Chefs and the commercial food industry to enhance the flavor
of a wide variety of foods use MSG frequently. It is also sold in supermarkets
as “Accent” and has been used by many people to flavor foods prepared at home
for many years in the U.S. and even longer in parts of Asia. Some researchers
regard the flavor of MSG to a fifth taste in addition to salty, sweet, sour and
bitter. The Japanese call the taste of MSG "unami" and describe it as
a salty, meaty flavor.
The MSC is a group of symptoms that can occur in many people
after the consumption of fairly large amounts of MSG. In susceptible individuals
the MSC is most likely to occur about 15 to 25 minutes after the consumption of
at least 2-3g of MSG without solid food and on an empty stomach. Typical
symptoms such as a burning or heat sensation in the face, neck and upper torso
may be accompanied by a feeling of tightness or stiffness in the chest, arms
and/or back. There may also be a feeling of weakness, heart palpitations, and
diffuse pain in the chest area. These symptoms typically begin to subside
within 20 to 30 minutes after they start. Typically the MSC is gone completely
within an hour and never last as long as two hours.[3]
Some studies have reported a small increased risk of
headaches with very high doses of MSG. However, a recent double-blind placebo
controlled trial found no difference in headaches in subjects given either 1.5
or 3 g of MSG or a placebo (lactose) in capsules.[4]
If headaches are part of the MSC they are certainly an uncommon reaction and if
they occur at all as a result of MSG intake it is only when unusually large
amounts are consumed on an empty stomach. There are, of course, many anecdotal
reports of different symptoms and much longer lasting symptoms associated with
the intake of even small amounts of MSG. However, there is no credible research
from any well-designed studies that have found other symptoms that result from
the ingestion of MSG.
The MSC usually occurs when a fairly large amount of MSG is
consumed on an empty stomach in a broth or soup at an Oriental restaurant.
Typically at least 3-5g of MSG must be consumed within short period of time to
trigger the MSC. However, even in people who react consistently to MSG in a
liquid the same amount of MSG consumed with solid food does not usually elicit
the same reaction or any reaction at all in most cases.[5]
Under controlled conditions no objective changes in blood chemistry (except for
a transient rise in GLU levels), blood pressure, skin temperature, etc. have
been observed while people are experiencing these symptoms.[6]
So while the symptoms of MSC are clearly felt by many people there are no
accompanying physical changes in the body that can be measured objectively to
verify the presence of such symptoms.
The MSC can be triggered in perhaps 30% of Americans who
consumed at least one to two tsp. (3-6g) of MSG in a broth-type soup or other
liquid on an empty stomach. Even under these circumstances the consumption of
less than 2-3g of MSG is usually insufficient to create MSC symptoms in nearly
all people who report having experienced the MSC in the past. It should be
noted that more than 1g of MSG per serving in tomato juice or soup does not
usually improve overall palatability. Therefore, the amount of MSG needed to
maximally enhance flavor and sensory pleasure is well below the threshold for
triggering the MSC in nearly all people. The consumption of a high carbohydrate
food before or with the MSG usually blocks the MSC in susceptible individuals.
If MSG is used in moderation and consumed with some carbohydrate-rich food then
it seems unlikely that MSG will cause any physiological or psychological
changes in the body.
Despite the relatively transient and benign nature of the
MSC there are several groups of people and many individuals who claim MSG is
responsible for far more serious health problems than the relatively benign and
transient MSC. For example, the website for the National Organization to Stop
Glutamate has claimed that MSG caused “Headaches, migraines, stomach upset,
nausea, vomiting, diarrhea, irritable bowel syndrome, asthma attacks, shortness
of breath, anxiety or panic attacks, heart palpitation, partial paralysis,
‘heart-attack-like symptoms’, balance difficulties, mental confusion, mood
swings, neurological disorders (Parkinson’s, MS, ALS, Alzheimer’s), behavior
disorders (especially in children and teens), allergy-type symptoms, skin
rashes, runny nose, bags under the eyes, flushing, mouth lesions, depression,
and more.”[7]
However, the vast majority of these symptoms and all of the more serious health
problems listed on this website have not been shown to be related to the
consumption of MSG in well-designed scientific studies.
Promoters of nutrition quackery claim that a particular
supplement and/or diet is a miraculous cure for a variety of health problems.
Promoting fad diets and supplements as being effective for the treatment or
prevention of disease in the absence of credible scientific evidence is
quackery. Food terrorism is the flip side of nutrition quackery. A food
terrorist claims that some component of food is responsible for causing disease
in the absence of credible scientific evidence to support such a claim. Those
who claim MSG causes serious health problems have the burden of supporting
their claims. However, because the food terrorism surrounding the use and
safety of MSG has become so great there has been a fair amount of research
designed to establish the true impact of consuming MSG on the body.
It has been reported that MSG triggers asthmatic attacks in
people with asthma.[8]
However, in studies that reported that some people responded with bronchospasm
to MSG were flawed. In these studies the subjects were removed from their
asthma medication(s) a day or two before the MSG challenge and there was no
placebo group. Removal of medication was probably the reason for the increase
in symptoms on the following day rather than the exposure to MSG. Six
subsequent studies which were better designed and utilized a control group have
failed to find any difference in asthmatic symptoms with MSG compared with a
placebo. This was the case even though some of subjects in these studies had
believed MSG triggered bronchospasm in them prior to double blind testing. A
recent review found no evidence linking MSG use to asthma.[9]
Another study found no evidence of hives being triggered by
MSG in patients with chronic hives (urticaria).
[10]
It is very unlikely that MSG is ever the cause of allergic reactions. Indeed it
seems obvious that one cannot be truly allergic to an amino acid that is found
in every living plant and animal. People who have experienced food related
bronchospasms in an oriental restaurant were most likely responding to
sulfiting agents used to preventing browning of chopped vegetables. Because
asthma, hives and other allergic reactions can be triggered by emotions as well
as allergens it is quite possible that someone who reports hives, asthmatic or
other allergic symptoms to MSG may be responding emotionally simply because
they fear MSG was in something they ate and causes such symptoms. In some cases
perhaps some other allergen is present in the food or meal consumed along with
the MSG. Cold air, cigarette smoke, dust and other environmental insults are
more far more likely the cause of bronchospasm, which occurs in an Oriental
restaurant than is exposure to MSG. A double-blind challenge may be useful in
convincing patients that they are not really allergic to MSG.
There is no convincing scientific research linking the use
of MSG to asthma attacks or any other type of allergic reaction. Claims that
MSG is the cause of bronchospasm or other allergic reactions should be viewed
with skepticism. So how can all of the anecdotal reports of allergic-type
reactions to MSG be explained? The occurrence of psychosomatic induced symptoms
is well established.[11]
It is known that many more people believe they are “allergic” to foods and food
additives than can actually be demonstrated using objective examination such as
double-blind challenges.[12]
Extremely high levels of MSG have been shown to acutely
destroy brain tissue in weanling mice.[13]
However, in most animals GLU in the blood does not cross the blood-brain
barrier and causes no neurological damage. Chronic feeding of MSG to rabbits,
dogs and monkeys found that even doses as high as 42g MSG/Kg body weight failed
to cause any neurological damage.[14]
For a 70 Kg man this dose would be 2940 g daily or over 6 lbs of MSG per day.
There is a part of the hypothalamus that is not protected by
the blood brain barrier and it is this part of the brain that is damaged by
very high levels of MSG in the blood in weanling mice. This part of the brain
uses GLU as a neurotransmitter to trigger the release of pituitary hormones.
However, in human subjects consuming 12.7g of MSG was shown to have no effect
on any pituitary or other hormone levels even though this dose markedly
elevated plasma GLU levels.
Concern that MSG added to the maternal diet also might harm
the developing fetus or a breast fed infant appears to be unwarranted. This is
because increased GLU in maternal blood does not affect GLU in the brains or
other tissues of the fetus nor does it increase the GLU content of breast milk.[15]
It therefore seems most unlikely that the consumption of MSG poses any risk to
the brain of either adults or developing babies.
An epidemiological survey of about 5000 users and nonusers
of MSG in Hawaii found that chronic use of MSG was not associated with any
increase in neurological problems. It also showed that the regular use of MSG
did not affect serum cholesterol or blood sugar levels and had no effect on
body weight.[16]
Despite anecdotal reports that MSG contributes to all sorts of neurological
problems including Parkinson’s disease and Alzheimer’s' disease there is no
credible scientific research to support any damage to the neurological system
from the regular use of MSG.
People with hypertension are often advised to avoid MSG and
other sources of sodium. However, there is no evidence that sodium from MSG, or
sources other than salt raises BP or contributes to the development of HTN.
Indeed, sodium as salt (NaCl) has been shown to be far more toxic to the body than
sodium without the chloride such as MSG, sodium bicarbonate or sodium citrate.
In animals the acute lethal dose of MSG that kills 50% (LD 50) of rats and mice
(15,000+mg/kg b.wt.) is more than 10 times higher than that of salt.
[17]
Clearly then research in animals proves that MSG is far less toxic to the body
than salt.
The recent DASH-Sodium trial when coupled with other
research has demonstrated beyond a reasonable doubt that Americans should be
consuming far less than 1500 mg of sodium daily to reduce problems with high
blood pressure.[18] This
study showed that an increase in dietary sodium from salt from 1500mg to 2400mg
resulted in a significant increase in blood pressure in both normotensive and
hypertensive subjects. By contrast, the consumption of up to 120g of MSG (about
48,000mg of sodium) for an extended period of time did not increase blood
pressure at all. In fact, this extremely large amount of sodium from MSG
resulted in a slight drop in both blood pressure and blood sugar levels and
produced no detectable changes in neurological function.
[19]
Research has shown that when the same amount of sodium is fed as compounds
other than salt (i.e. sodium citrate, sodium bicarbonate and MSG) there is no
significant increase in blood pressure as occurs with a similar amount of
sodium from salt.[20] [21]
A teaspoon of salt has more than four times the sodium
content as teaspoon of MSG (2,150 Vs 492mg, respectively). If food that is
normally prepared with MSG is prepared without it the flavor and sensory
pleasure associated with its consumption will be reduced. To compensate for
this loss of flavor enhancement most chefs and food manufacturers would likely
compensate for the loss of MSG by the addition of more salt or salt-rich
ingredients such as soy sauce. By contrast, if MSG were used in place of salt
in the preparation of soups, salad dressings, sauces, French fries, chips, etc.
then the amount of salt and sodium these foods contain would be reduced by over
75%. Food manufacturers could use a combination of MSG and monopotassium
glutamate in many foods in place of most of the salt and drastically reduce the
salt (and sodium) content of many food items.
In contrast to the dearth of credible scientific evidence
linking the consumption of MSG with any serious health problem in humans there
is compelling scientific evidence linking excessive salt intake with a wide
variety of serious and common health problems. Because of the growing
reluctance of chefs and food manufacturers to use MSG due to the tactics of
food terrorist it is likely that salt intake may be increased. The removal of
MSG from a recipe often results in a need for greater amounts of salt and salty
ingredients to enhance flavor.
A diet high in salt has been shown to reduce peak bone mass
in young females.[22] In
postmenopausal women, an increase in dietary salt has been shown to result in a
reduction in bone mineral density and an increased risk of osteoporosis.[23]
Increasing dietary salt has consistently been linked with an increased
excretion of calcium in the urine. However, the same amount of sodium given
without chloride has no effect on calcium loss.[24]
This suggests that replacing salt with MSG would reduce the risk of developing
osteoporosis.
About 8-15% of people in the U.S. will develop kidney stones
during their lifetime. The increase loss of calcium in the urine that results
from consuming increasing amounts of salt is also believed to contribute to the
development of kidney stones.[25]
Because sodium without chloride does not increase calcium excretion it seems
likely that replacing dietary salt with MSG may help reduce the risk of kidney
stones. Increasing dietary salt tends to increase blood pressure. Even modestly
elevated blood pressure was recently shown to greatly increase the risk of
developing kidney cancer.[26]
Because sodium without chloride does not appear to raise blood pressure it
seems likely that replacing salt with MSG may reduce the risk of kidney cancer.
Dietary salt is caustic to the esophagus and gastric mucosa.
In China an increased intake of salty foods has been linked to an increased
risk of esophageal and stomach cancer.[27]
Excess dietary salt is known to promote atrophic gastritis, which sets the
stage for the development of stomach cancer.[28]
[29]
By contrast, there is no evidence linking the consumption of MSG to either
gastric atrophy or stomach cancer.
Excessive salt intake has been associated with an increased
risk of developing high blood pressure, stroke, coronary artery disease, heart
and kidney failure, osteoporosis, stomach cancer, and possibly kidney stones.[30]
Too much dietary salt may also promote headaches and may increase bronchospasm
in people with asthma. Overall the scientific evidence linking excessive salt
intake to a wide variety of serious diseases is compelling. By contrast, the
use of MSG in place of salt may help prevent all these serious health problems.
It makes little sense from a public health perspective to advocate the removal
of MSG from food when the likely consequence will be an increased reliance on
salt and salty ingredients such as soy sauce.
1. The MSC is an unpleasant reaction that results from the
consumption of fairly large amounts of MSG. As many as 30% of people may be
susceptible to this symptom complex if large amounts of MSG (5g or more) are
consumed on an empty stomach in a liquid (usually a brothy soup). The MSC
generally lasts about 20 to 30 minutes and rarely as long as one hour.
2. The MSC can be avoided in most cases if a high
carbohydrate food is consumed before or with the MSG or if the total amount of
MSG consumed at one meal is no more than 2g in a liquid. If the MSG intake is
limited to 2g or less and/or consumed with solid foods no one has been shown to
experience the MSC even though many people have been tested in carefully
controlled studies.
3. Claims that MSG causes neurological damage in the fetus,
newborns, or adults are without scientific merit. Claims that MSG causes
Alzheimer’s disease, Parkinson’s disease, multiple sclerosis or Lou Gehrig’s
disease (ALS) are specious.
4. Claims that MSG causes allergic reactions or bronchospasm
in people with asthma have not been demonstrated in properly designed and
blinded studies. People who believe MSG causes heir asthmatic symptoms should
be tested in a blinded fashion with capsule containing MSG or a placebo.
Believing that MSG is causing asthmatic symptoms may discourage people from
seeking the true allergens or environmental stressors that are triggering the
bronchospasm.
5. The same amount of sodium consumed as MSG is far less
toxic to the body than an equivalent amount from salt. Avoiding MSG could
contribute to an increased salt intake. Replacing salt with MSG (tsp for tsp)
may help prevent or lower high blood pressure. It would also reduce the loss of
calcium in the urine and may help reduce the risk of osteoporosis and kidney
stones.
6. Replacing salt with MSG may also reduce the risk of
stomach and esophageal cancer. By preventing HTN, replacing salt with MSG may
also reduce the risk of kidney cancer.
7. There is a lot of irrational fear and concern about the
use of MSG as a food additive in America. This fear is largely the result of
unsubstantiated claims of health problems blamed on MSG. It seems likely that
nearly all of the serious health problems and most of the unusual symptoms,
which are believed to be caused by MSG, are due either to something else or are
psychosomatic in origin. The irrational fear many people now have about
consuming even small amounts of MSG is largely the result of a
well-orchestrated campaign of food terrorism.
8. Believing that small amounts of MSG consumed with solid
foods can cause symptoms like heart palpitations, shortness of breath, weakness
and chest pain may lead some people to dismiss symptoms of a heart attack as
simply an adverse reaction to MSG. This could be a fatal error. Chest pain or
tightness that is not accompanied by flushing or burning sensations is unlikely
to be related to MSG intake.
9. There is better evidence linking salt intake to
headaches, including migraines than there is linking headaches to MSG intake.
FMI:
http://www.fda.gov/opacom/backgrounders/msg.html
http://ificinfo.health.org/brochure/msg.htm
[1] Kwok RHM. Chinese restaurant syndrome (letter). N Engl J Med 1968;278:796
[2]
Raiten DJ, Talbot JM, Fusher FD,
editors. Analysis of adverse reactions to MSG). Federation of American
Societies for Experimental Biology Publisher. American Institute of Nutrition,
1995, p. 1-119
[3]
Kenney RA, Tidball CS. Human
susceptibility to oral monosodium L-glutamate. Am J Clin Nutr 1972;25:140-6
[4]
Prawirohardjono W, Dwiprahasto I, Astuti
I, et al. The administration to Indonesians of monosodium L-glutamate in
Indonesian foods: an assessment of adverse reactions in a randomized double blind,
crossover, placebo-controlled study. J Nutr 2000;130:1074S-6S
[5]
Geha RS, Beizer A, Ron C, et al.
Multicenter, double-blind, placebo controlled, multiple challenge evaluation of
reported reactions to monosodium glutamate. J Allergy Clin Immunol 2000;106:973-80
[6]
Geha RS, Beiser A, Ren C, et al. Review
of alleged reactions to monosodium glutamate and outcome of a multicenter
double-blind placebo controlled study. J Nutr 2000;130(Suppl):1058S-62S
[7]
www.nomsg.com 3/6/01
[8]
Allen DH, Delohery J, Baker G. Monosodium
L-glutamate-induced asthma. J Allergy Clin Immunol 1987;80;530-7
[9]
Stevenson DD. Monosodium glutamate and
asthma. J Nutr 2000;130(suppl):1067S-73S
[10]
Simon RA. Additive-induced urticaria:
experience with monosodium glutamate. J Nutr 2000;130(Suppl):1063S-66S
[11]
Shorter E. From paralysis to fatigue: a
history of psychosomatic illness in the modern era. 1993, Free press
[12]
Altman DR, Chiaramonte LT. Public
perception of food allergy. J Allergy Clin Immunol. 1996;97:1247-51
[13]
Olney JW. Brain lesions, obesity and
other disturbances in mice treated with monosodium glutamate. Science, NY
1969;164:719
[14]
Heywood R, Worden AN. Glutamate toxicity
in laboratory animals. In Glutamic Acid: Advances in Biochemistry and
Physiology. Edited by LJ Filer,Jr et al. p. 363. Raven Press, New York
[15]
Fernstrom JD. Pituitary hormone
secretion in normal male humans: acute responses to a large, oral dose of
monosodium glutamate. J Nutr 2000;130(Suppl): 1053S-7S
[16]
Go G, Nakamura FH, Rhoads GG, Dickerson
LE. Long-term health effects of monosodium glutamate. Hawaii Med J.
1973;32:13-7
[17]
Walker R Lupien JR. The safety
evaluation of monosodium glutamate. J Nutr 2000;130:1049S-52S
[18]
Sacks FM, Svetsky LP, Vollmer WM, et al.
Effects on blood pressure of reduced dietary sodium and the dietary approaches
to stop hypertension (DASH) diet. N Engl J Med 2001;344:3-10
[19]
Bazzan G, D'Elia JA, Olson RE.
Monosodium glutamate: feeding large amounts to man and gerbils. Science
1970;169:208-13
[20]
Kurtz TW, Hamoudi AA, Morris RC.
"Salt-sensitive" essential hypertension in men. N Engl J Med
1987;317:1043-8
[21]
Boegehold MA, Kotchen TA. Importance of
dietary chloride for salt sensitivity of blood pressure. Hypertension
1991;17(Suppl 1):158-61
[22]
Matkovic V, Ilich JS, Andon MB, et al.
Urinary calcium, sodium, and bone mass of young females. Am J Clin Nutr
1995;62:417-25
[23]
Zarkadas M, Gougeon-Reyburn R, Marliss
EB, et al. Sodium chloride supplementation and urinary calcium excretion in
postmenopausal women. Am J Clin Nutr 1989;50:1088-94
[24]
Massey LK, Whiting SJ. Review: dietary
salt, urinary calcium and bone loss. J Bone and Min Res 1996;16:731-6
[25]
Pak CYC. Kidney stones. Lancet
1998;351:1797-801
[26]
Chow W-H, Gridley G, Fraumeni JF,
Jarvholm B. Obesity, hypertension, and the risk of kidney cancer in men. N Engl
J Med 2000;343:1305-11
[27]
Lu J-B, Qin Y-M. Correlation between
high salt intake and mortality rates for esophageal and gastric cancers in
Henan Province, China. Int J Epidemiol 1987;16:171-6
[28]
Fuchs CS, Mayer RJ. Review article:
gastric carcinoma. N Engl J Med 1995;333:32-41, Joosens JV, Geboers J. Dietary
salt and risks to health. Am J Clin Nutr 1987;45:1277-88
[29]
Kono S, Hirohata T. Nutrition and
stomach cancer. Cancer Causes Control 1996;7:41-55
[30]
Kenney JJ. Salt: Has it been given a
fair shake? Or is it a serial killer? http://www.foodandhealth.com
Back to the top
Home | Contact | About | License & Copyright Statement | Privacy Statement
Copyright 2008. Food and Health Communications, P.O. Box 266498, Weston, FL 33326
Sales: 800-462-2352, Info: 954-385-5328, Fax: 954-385-5329
All FHC nutrition education products meet the 2005 Dietary Guidelines and MyPyramid goals.
This site is rated "Better than Most" by Tufts Nutrition Navigator
Site by AbleDesign
| 
