IGIS responds to allegations about glutamate made by Truth in Labeling
23 November 2002
The latest edition of New Scientist contains a letter from Truth in Labeling
which makes allegations about the safety of glutamate. The following is a
transcript of the letter (in italics) followed by the facts about
glutamate:
How safe is glutamate?
From Adrienne Samuels
Truth in Labeling
People now ingest undetermined amounts of free glutamic acid in the flavour
enhancer monosodium glutamate, in other ingredients and in fruits, grains and
vegetables that have been sprayed with MSG as they grow.
Free glutamate is a natural component of many foods we eat as part of a
normal diet such as meat, fish, vegetables like tomatoes and mushrooms, and
cheese. Each day the average person consumes between 10g and 20g of glutamate as
part of their normal diet, most of which is consumed as glutamate in the protein
in foods. Generally the amount of glutamate added to food as seasoning is in the
range of 0.1% to 0.8% of the food consumed so people who consume MSG as
seasoning very regularly will be eating perhaps 1g - 3g a day. The body treats
glutamate in exactly the same way whether it comes from these sources or from
seasoning added to food.
Monosodium glutamate is not sprayed onto crops as they grow.
Glutamic acid as part of a protein has important nutritional value. Free
glutamic acid, if injected or applied directly, is capable of killing brain
cells.
Glutamic acid is one of 20 amino acids required for healthy development
including the making of proteins in the body. The human body produces 48g of
glutamate as part of normal metabolism.
Injecting any ingredient directly into the brain is likely to cause
damage.
Hiroshi Ohguro speculates that a diet high in glutamic acid might raise
glutamic acid levels in the eyeball (26 October, p.11). Recent research has
linked such rises to glaucoma. As New Scientist reported, Ohguro found that very
large amounts of monosodium glutamate cause retinal damage in rats.
The doses of glutamate fed to the rats were extremely high (neither of the
experimental diets supplemented with glutamate could be considered simply 'high'
let alone 'moderate'). The amounts would be the equivalent of a human consuming
more than 500g of additional MSG as seasoning every day for months which makes
the research irrelevant to human consumption levels.
There is no evidence that lesser amounts of monosodium glutamate over a
lifetime won't cause retinal damage in people, too.
This statement ignores what we know about glutamate's role in the body and
its metabolism. The body contains about 1,800 g of glutamate (in a 70 kg adult)
of which about 10g is free glutamate. Between 10g and 20g of glutamate is
consumed everyday and absorbed for use by the body in normal metabolism. The
body itself produces glutamate during normal metabolism - approximately 48g of
glutamate is turned over in the body everyday. In addition, the average person
excretes about 16g of glutamate everyday. Glutamate, from whatever source,
consumed as part of a normal diet would be metabolised and would not build
up.
The Truth in Labeling Campaign has observed that some MSG-sensitive people
can eat a particular "fast food" on a single day without experiencing
MSG-reactions - such as nausea, drowsiness and headaches. Yet when these people
eat that same fast food two or three days in a row, typical MSG-reactions
occur.
Anecdotal reports of adverse reactions to various foods or food ingredients
are not uncommon. Research has shown that people who believe they adversely
respond to MSG do not do so when evaluated in carefully controlled testing
situations.
The glutamate industry, in the form of the International Glutamate
Information Service, responded to the New Scientist story with a press release
and letters to the other media that reported the study, including on to New
Scientist (16 November, p.24). Since 1969, the industry has been claiming that
glutamate is safe.
Yet a 1995 review by the Federation of American Societies for Experimental
Biology concluded that MSG can cause adverse reactions in an "unknown
percentage" of people.
In its 1995 report to the FDA, following a comprehensive review of the
scientific literature about monosodium glutamate, the Federation of American
Societies for Experimental Biology (FASEB) concluded that there is no difference
between naturally occurring free glutamate found in mushrooms, cheese and
tomatoes and the glutamate from monosodium glutamate. FASEB found no evidence
linking MSG to any serious or long-term effects. The report led the Food and
Drug Administration to conclude that MSG is a safe food ingredient at normally
consumed levels.
Virtually every migraine clinic in the US recognises monosodium glutamate as
a potential headache trigger, for example.
Research shows that glutamate and MSG are not headache triggers. A 1990
review of the literature on food-triggered headaches (Food triggered migraine: a
critical review. Annuls of Behavioural Medicine, 12:51-651, 1990) states that
there is no evidence to support an association between MSG and migraine
headaches.
Glutamate occurs in a wide range of foods we consume as part of a normal diet
including meat, fish, vegetables and dairy products. Glutamate from MSG
contributes just a fraction of our daily intake. The body treats glutamate from
MSG seasoning and glutamate from other foods in exactly the same way.
The International Glutamate Information Service claims that accurate
information can be found at its website, www.glutamate.org. An alternative view
can be found at www.truthinlabeling.org.
Chicago, Illinois, US