Pakistan Notmilk/Notmeat Newspaper Story
- If you continue to consume dairy products and meat,
read this and weep:
Molecule Found in Meat, Milk gives rise to Tumors
Saturday October 1, 2005
ISLAMABAD: A non-human molecule found in red meat and milk makes its
way into the human system when eaten -- and seems to build up
especially in tumors, according to U.S. researchers report.
The compound, called sialic acid, is found on the surfaces of animal
cells but is not found in people, and may be one reason why animal-
to-human organ and tissue transplants do not work well. Animals have
a version called Neu5Gc, while humans carry Neu5Ac.
But researchers at the University of California San Diego found it
does show up in the human body, and showed it can be absorbed from
eating red meat and milk.
They also showed that the body produces an immune response against
Dr. Ajit Varki and colleagues, reporting in the Proceedings of the
National Academy of Sciences, say it is too soon to make any
recommendations based on their findings.
"Of course, there are already existing recommendations that people
should not consume too much food containing saturated fats, such as
dairy products and red meats," Varki said in a statement.
"The highest amount (of Neu5Gc) was found in lamb, pork, and beef
(so-called 'red meat')," the researchers wrote. Levels were very low
or undetectable in poultry and fish, vegetables and hen's eggs.
Varki, who is not a vegetarian, noted that many studies have linked
a diet rich in meat and milk with cancer, heart disease and other
"The small amounts of Neu5Gc in normal tissues also raise the
possibility that anti-Neu5Gc antibodies are involved in
autoimmunity," the researchers said.
Autoimmune disease occur when the body mistakenly attacks healthy
tissue and include type-1 or juvenile diabetes and some types of
arthritis. "In this regard, it is interesting that vegetarian diet
has been suggested to improve rheumatoid arthritis," they wrote.
But much research has focused on the fat content of animal fat or
byproducts of cooking meat as the cause of disease.
Varki's collaborator Dr. Elaine Muchmore developed an antibody -- an
immune system targeting protein -- that would hook onto Neu5Gc. The
team found Neu5Gc in human tumor samples and to a much lower degree
in healthy tissue.
More tests showed that most people had made their own antibodies
that recognized Neu5Gc, and thus could potentially initiate an
inflammatory immune response.
Varki and two colleagues drank Neu5Gc purified from pork sources,
and the molecule showed up in their urine, blood, hair and saliva.
"We need to find out if there is any association between the
presence of Neu5Gc and/or the anti-Neu5Gc antibodies with any
disease," Varki said. "This will require large-scale population
In some cases the human immune response was similar to that seen
when people are exposed to another animal molecule, this one a cell
surface molecule called alpha galactose.
Varki noted that the molecule is almost certainly not immediately
toxic to people.
"Meat eating has certainly been a feature of human ancestors for
many hundreds of thousands of years," he said.
"Thus, it is indeed possible that humans have developed some kind of
tolerance or indifference to Neu5Gc. However, most humans are
continuing to make antibodies against Neu5Gc."
It could be that the damage only builds up over years -- and that as
people live longer, the consequences make themselves felt.
"However, we are now living longer and the question arises whether
the gradual accumulation of Neu5Gc and the simultaneous presence of
antibodies against could be involved in some diseases of later
life," he said.