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SELENIUM:
AN ESSENTIAL TRACE MINERAL
by Lynn Hinderliter, CN, LDN
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In the 1990s there was a great deal of heightened
interest generated in a comparatively little known trace mineral named
Selenium. Holistic Health Professionals have known for some time that
selenium plays a part in the antioxidant enzyme Glutathione Peroxidase,
(whence its abbreviation, SeGPX) which is arguably the most important
factor in resistance to free radical damage at the cellular level.
Therefore, low levels of selenium have been implicated in most chronic
disease states, to include cancer, premature aging, cataracts, AMD,
cardiovascular disease, osteoarthritis and more.
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The research,
however, left little doubt as to the extreme importance of
paying attention to selenium levels in the diet.
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A case in point: in the 1970s, it was
discovered that those suffering from a form of juvenile heart disease
called Keshan (after a Chinese county), which was characterized in
children between 2 and 10 by heart enlargement, heart weakness and
irregular rhythm, and fluid on the lungs, had the lowest levels of
selenium in their tissues of anywhere in the world!
Supplementing with selenium
considerably reduced incidences of the disease, though a possible
viral connection meant that not all sufferers responded. This would
tie into research done in the 1980s and 1990s, which suggests that
viruses become more dangerous where a selenium deficiency exists.
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One very important fact
about trace minerals is that if they are not present in the
soils where foods are grown,
then they will not be present in the food.
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The food crops will grow
normally, the animals to whom they are fed will develop normally, but
they are not dependent on selenium for health, we are: and we will not
be getting it! Interestingly, about 50% of the land mass in the U.S.
is either deficient in, or barely at the acceptable level for,
selenium. It is therefore obvious that the food chain is going to be a
somewhat unreliable source for a steady supply of this important
element.
How important?
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Avian flu
heightened interest in research showing that more virulent
viruses develop in selenium deficient hosts
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Many
new viruses, together with ever more deadly versions of old diseases,
are first found in developing countries, which also suffer from
extensive nutritional deficiencies.
Put
this together with research from the University of N. Carolina, which
discovered both that mice deficient in selenium became seriously ill
with lung infections when infected only with a minor flu strain,
and were subsequently found to have developed several viral mutations,
many of them ever more virulent, and the selenium connection looks
pretty compelling. (Trends in Microbiology,
2004, Vol. 12, pp. 417-423)
The
conclusion of the researchers appears to be that taking a selenium
supplement if one is low in the mineral, might well make a difference
to one's susceptibility to a virus, though of course, no one knows
whether it would affect resistance to H5N1, or avian flu.
Selenium
has many powerful effects, being a part of at least 25 proteins with
antioxidant properties, and in its absence, causing both T-lymphocyte
activity and antibody production ( important for immunity) to be
adversely affected.
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The lower
your level of selenium,
the higher your risk of osteoarthritis
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Heading a research group
from the University of Carolina, study leader Dr. Jordan determined
that for every additional tenth of a part per million of selenium in
volunteers' bodies, there was a 15-20 per cent decrease in the risk of
knee osteoarthritis.
"Our results suggest that we might be able to prevent or delay
osteoarthritis of the knees and possibly other joints in some people
if they are not getting enough selenium,” said Dr. Jordan.
The findings were presented in San Diego at the annual meeting
of the American College of Rheumatology in 2005.
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Studies show that selenium
supplementation is tied to a dramatic reduction
in the number of cancer cases
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and to the number of cancer
mortalities. One such study was both significant enough and of a high
enough quality to be published in the prestigious Journal of the
American Medical Association.
The author of the study, Dr. Larry
Clark, became interested in selenium because while doing a study of
cancer mortality in North Carolina in the early 1980s, he noticed that
there was a pattern of excess mortality from cancer that appeared to
follow a geological map of the area. At first, he though this could be
explained by pesticide use high in arsenic, or low carotenoid intake,
and he was also looking at selenium intake, since selenium is an
antagonist of arsenic.
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He finally determined that
selenium was directly correlated with the cancer data, and
that in fact counties where selenium levels in the soil were
low, there was a 10% higher mortality from cancer.
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Building on Dr. Clark's research, a
recent (1999)study at the University of Colorado began following 1,312
patients with skin cancer. They were divided into 2 groups, one
receiving organic selenium, the other a placebo. After 4 years,
there was no discernible difference in the skin cancer rates, BUT when
the researchers looked at other more life-threatening kinds of cancer,
they found what Dr. Tim Byers, Professor of Preventive Medicine,
called "the most exciting finding we've ever had in nutrition and
cancer." The selenium supplemented group had 63% fewer cancers of
the prostate, 58% less cancer of the colon, and 46% less lung cancers
than the placebo group. The Selenium used was a high selenium
yeast called Selenomax.
A 2000 study using laboratory rats
found selenium from broccoli was highly effective in protecting rats
against potent injected carcinogens, with the protection increasing as
the doses rose. You can access this study at www.ars.usda.gov.
In 2004, more
studies in the Journal of the National Cancer Institute concluded:
"The new epidemiologic data on selenium from Li et al.
continue to support the initial impressions of this agent's
tremendous potential as a prostate cancer preventive agent.
The emerging laboratory data greatly strengthen the
biologic plausibility for this optimism and for the ongoing
randomized clinical selenium trials, which ultimately will
be necessary to define the potentially complex
risk–benefit profile of this promising preventive agent .
Meanwhile, science will continue peeling back layer after
layer of the enormously deep and complex onion of selenium
effects in the prostate." http://jncicancerspectrum.oupjournals.org/cgi/content/full/jnci;96/9/645
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What results can be
brought about by optimizing one's levels of selenium?
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Dr. Clark's 10 year study showed cancer
mortality reduced by 50%, and overall mortality by 17%. Total cancer
incidence was reduced by 37%, and three major kinds of cancer were
especially affected: lung cancer was reduced by 46%, prostate cancer
by 63%, and colon cancer by 38%. (JAMA 1996:276;1957-1963). Dr.
Byers study confirms this result with even better odds!
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Selenium and
Colon Cancer
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Evidence continues to
mount that Selenium is intimately connected with rates of colon
cancer. I have one link in Resources to a study suggesting that,
and now an analysis of 3 studies comprising more than 1500 patients
showed that those with the highest blood levels of selenium had the
least risk of recurrence of colon cancer.
The researchers were
clear: "higher selenium status may be related to decreased risk
of colorectal cancer," write the researchers in the Nov. 17 issue
of the Journal of the National Cancer Institute. (J
Natl Cancer Inst 2004;96:1645-1647,1669-1675.)
A particular "hero" of mine,
Dr. Richard Passwater, goes into considerable detail about the
variations of selenium content in the diet: he quotes one FDA survey
which found NO selenium in five samples of a "balanced" diet
in 1967. He himself reported in 1973 that he was unable to find any
selenium in several TV dinners he analyzed. Refining, processing and
cooking have an effect on selenium contents. It appears obvious that
this is one incontrovertible case where only supplementation can
assure one of proper levels of the mineral.
Consider also the fact that adequate
levels of selenium are found only in a few states, and can be achieved
through the diet only by eating locally grown foods...
It mush be remembered, though, that Selenium is after
all considered a trace mineral, and high doses should be used
with caution. In 2007, an eight year study concluded that taking
more than 200 mcg of selenium daily could be connected to the
development of blood sugar imbalances. The researchers commented that
the risk of developing diabetes tended to be higher in people who had
higher blood selenium levels at the start of the study.
How fortunate we are to be living in a
time when this kind of research allows us to come up with inexpensive
and effective ways to support our health : how fortunate, too, to be
able to find the answers to the kind of question: why is this
happening? Perhaps the day is not far away when we will know why many
of the problems that plague us happen, and what we can do in detail to
prevent them - perhaps we will even follow the ancient Chinese model
of health care, when we pay our Health Professionals a stipend as long
as they keep us healthy, and withhold payment when we become sick! It
makes perfect sense to me!