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TWO readers of my piece on alternative medicine (MT, March 28)
wanted to know if there’s clinical evidence that glucosamine is
really effective against arthritis.
The quick answer is none, or more precisely,
research is still being done. The US National Institutes of Health (NIH)
is in fact sponsoring such a study.
The condition called arthritis is the
inflammation of the joints, causing pain and swelling. Treatment is
usually based on analgesic drugs, steroids, and gold salts. In
really bad cases, surgery may be necessary to replace the affected
joints.
Glucosamine is an amino sugar, CH2 OH (CHOH),
CHNH2 CHO, that derives from glucose. It’s mainly chitin, the
substance that the exoskeleton of arthropods and some species of
fungi is made of. Chitin is insoluble.
The stated purpose of glucosamine that one
usually finds on the label is to help reduce “joint pain,
including helping to relieve pain due to osteoarthritis.” It’s
also supposed to “build healthy cartilage and protect against the
deterioration of cartilage related to chronic joint disease.” No
therapeutic benefit is claimed. It could very well be a placebo.
Although not directly related to the question
that was posed by my interlocutors, the case of Ambrotose in the
Nov. 2, 2007 issue of Science may be of some help.
The US Congress enacted in 1994 a law that
allows the sale of food supplements without Food and Drug
Administration (FDA) approval, provided that no therapeutic benefit
is claimed.
In July last year, the attorney general of Texas
charged Mannatech Inc., the manufacturer and distributor of Ambrotose,
of violating federal and state law and sued to stop the company
“from making claims that its products cure diseases.”
Mannatech denied the accusation but revised its
promotional materials.
Ambrotose is made from larch bark
arabinogalactan, aloe vera gel, gum ghatti and gum tragacanth, “a
blend of specific plant saccharides that support the immune system
[and] . . . optimal cell-to-cell communication,” to quote from one
of Mannatech’s brochures.
The suit is supported by some glycobiologists (glycobiology
is a new field that deals with the metabolism of sugar) one of whom,
Ronald Schnaar of Johns Hopkins University, said: “It’s none of
our business as glycobiologists if neutraceutical companies want
to sell bark extract. When they begin to tie it to our discipline,
that is the problem.”
According to the attorney general, Mannatech’s
sales people claimed that gluconutrients have cured diseases such as
Down Syndrome and cancer. They also claimed “scientific validation
from the field of glycoscience.” Mannatech puts out a magazine
called Glycoscience & Nutrition that, it says, is a
“peer-reviewed scientific journal.”
However, independent peer-reviewed studies on
Ambrotose did not find any evidence of health benefits in larch
bark. Since it’s not digested, its main effect is flatulence. A
clinical trial of aloe vera gel that appeared in a PubMed-listed
journal also did not find any benefit for the immune system. The
overall conclusion is that any claim that a combination of
saccharides improves health is “flawed” because cells produce
all the needed sugars from the glucose that people ingest.
Not all glycobiologists agree with these
findings. Robert Murray, a retired professor of biochemistry at the
University of Toronto and a consultant of Mannatech, wrote in a 2006
edition of a biochemistry textbook that although the body can make
monosaccharides from glucose, “there is evidence that the other
sugars may be beneficial in some circumstances when added to the
diet. This has led to the development of glyonutrient
supplements.”
Despite this clear endorsement, Murray demanded,
through his lawyer, that his name be removed from an editorial in
Glycoscience that took Mannatech and its products to task. Oxford
University Press, the publisher, complied with his request and in
fact went as far as to embargo the entire editorial, pending
“responses” by all sides.
Mannatech called the editorial “a deliberate
attack…based on false statements.” It has spent over $20 million
on research, it said, and has presented its findings in many
conferences.
Other experts, including Raymond Dwek of Oxford
University (he coined the term “glycobiology”), say that it’s
too soon to make definitive judgments about glyconutrients.
When pressed, even the critics of Mannatech
recognize that research on the health benefits of specific sugars
could be of value.
Thus, research by companies like Mannatech
should be welcomed provided that it is based on “solid science.”
A lot of money is also at stake. In 2006,
Mannatech earned $400 million from worldwide sales.
Should people continue to buy food supplements
like Ambrotose? If you can afford them and they cause you no harm,
perhaps, but it’s probably better to await the results of the work
of the NIH on alternative medical remedies.
mlatimes@gmail.com
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