- (Note - Canola Oil has been tagged as the cause of 35,000
cases of autoimmune diseases in Spain...how many in the US and Canada?)
- NEW YORK - What's
to blame when our bodies' defenses turn against us? New research out this
month indicates that environmental factors, ranging from ultraviolet radiation
to industrial chemicals, may be the cause of autoimmune disorders like
rheumatoid arthritis and lupus.
- "The concern is that there are these chemicals out
there in the environment, and could be at a concentration high enough to
produce autoimmune diseases," said Robert Luebke, a research biologist
for the Environmental Protection Agency.
- Previous research on autoimmune disorders, which affect
about 3 percent of the population, has centered on sufferers' inherited
susceptibility to these diseases, and some experts think infectious agents
such as viruses also play a role.
- But The National Institute of Environmental Health Sciences,
part of the National Institutes of Health, has published a special supplement
to its medical journal Environmental Health Perspectives exploring the
link between environmental agents " anything we eat, drink, breath,
or absorb into our bodies " and autoimmune disorders.
- In the journal, a group of researchers from the University
of California-Davis examined a long list of common xenobiotic (nonliving)
substances and found that many trigger can an autoimmune response, meaning
they produced high levels of autoantibodies in human or animal research
subjects. The presence of autoantibodies indicates the immune system is
attacking its own tissue (see sidebar for details).
- The list includes: * Common chemicals such as mercury
and iodine; * Vinyl chloride, which is used to manufacture PVC plastic;
* Canavanine, a substance produced by alfalfa sprouts; * Silica, one of
the most common elements in the Earth's crust; * Ultraviolet radiation
and ozone, which a produce a flood of free-floating oxygen ions that can
severely damage the body " especially the immune system.
- Another paper by Evelyn Hess of Cincinnati Medical Center
lists additional suspects: * Some types of hair dye * Heavy metals like
gold and cadmium * Rapeseed (canola) oil, responsible for 35,000 cases
of an autoimmune diseases in Spain; * L-tryptophane, the naturally occurring
hormone that makes you sleepy after eating a Thanksgiving turkey but which
until recently was sold as an over-the-counter dietary supplement. It was
traced to an outbreak of a lupus-like disease in 1990 in the U.S., and
was subsequently banned for public sale by the Food and Drug Administration.
- Why Mostly Women?
- Researchers also want to know why autoimmune diseases
disproportionately affect women: More than 70 percent of sufferers are
- "For almost all autoimmune diseases, women are at
greater risk for men," said Glinda Cooper, an epidemiologist with
the NIEHS Environmental Diseases and Medicine Program and co-author of
one of the journal articles.
- The answer may lie in women's elevated levels of estrogen,
which some theorize damages the body's immune system over time. "For
some of the autoimmune diseases, the risk is highest in the reproductive
years when estrogen levels are highest," Cooper noted.
- Another intriguing theory suggests that women "
or, more specifically, mothers " are prone to autoimmune disorders
because some of the fetus' cells inevitably get mixed up with mother's,
causing an overzealous immune-system response when T-cells recognize the
presence of an intruder.
- The Single-Cause Fallacy
- Despite autoimmune researchers' newfound focus on environmental
factors, experts suspect that they will never track the diseases to a single
cause. More likely, some people are predisposed to autoimmune diseases,
but the disorders don't occur without an environmental trigger.
- Hess writes that "It would appear that for any one
compound or environmental agent, genetic factors may differ."
- "There are many people exposed to purported risk
factors," seconded Dr. G. Wendell Richmond, a private practice immunologist
in Oakbrook, Ill. "But only a few come down with the diseases. That
suggests a large genetic factor."
- As interest grows in diseases like lupus and rheumatoid
arthritis " Congress earmarked $30 million in the 1999 NIH budget
to study autoimmune disorders " researchers agree environmental causes
are now an important part of the scientific effort.
- "The consensus coming out of the journal and the
workshop is that there appears to be a role of environmental influences
that would be worthwhile to pursue," Cooper said.