Selenium is one of those micro-nutrients which although
required by the body in only tiny quantities are
nevertheless vitally important for the health and
well-being of the human organism.
There's now compelling evidence of selenium's significance
as an anti-oxidant, in fighting cancer and heart disease,
and as a stimulant for the immune system.
Selenium's importance as an anti-oxidant lies principally
in its necessity for the production of the key anti-oxidant
enzyme, glutathione, which forms one of the body's first
lines of defence against dangerous superoxide free
radicals. The body particularly needs the fat-soluble
glutathione to work with vitamin E to soak up and
neutralise any free radicals attacking the delicate yet
vital fatty structures of cells such as the membranes.
In this way selenium and vitamin E appear to work so
closely together that a deficiency in one may be
compensated for by the other, and selenium is also crucial
as part of the enzyme thioredoxin reductase which is
important in maintaining the anti-oxidant properties of
vitamin C. Moreover, vitamin E cannot itself do its work
in the absence of an adequate supply of active vitamin C;
and vitamin C cannot remain active without the presence of
glutathione.
Selenium therefore forms part of a complex web of
interacting nutrients, each of which is essential to a
successful anti-oxidant rich diet, and whilst the amounts
of selenium required by the body may be tiny, the
Recommended Dietary Allowance (RDA) being set at just 55
micrograms per day, the effects of any deficiency can be
nevertheless disastrous.
It has to be said that a microgram (mcg) is a very small
quantity indeed – a mere one thousandth of a milligram, so
it might seem highly unlikely that anyone in an affluent
Western society could allow himself to be deficient. And
indeed, a little attention to the daily diet should ensure
that this is the case.
The richest food source of selenium, by far, is brazil
nuts, and amazingly a single nut may provide as much as 100
mcg. A mere one ounce serving of nuts may yield more than
800 mcg, more than double the Food and Nutrition Board's
recommended upper safe limit of 400 mcg. But luckily both
organ meats and seafoods such as shrimps, crabmeat, salmon
or halibut may provide selenium in much more manageable
amounts of up to 40 mcg in a 3 oz serving. Muscle meats
are also a reasonably good source, although pork, the best
of these, will only provide around 33 mcg per 3 oz.
Whole grains such as brown rice or wholemeal bread may
provide 15-20 mcg per serving, but fruits and vegetables
are not particularly useful sources because of the way in
which modern intensive farming procedures continue to strip
soils of their mineral content.
Nevertheless, most healthy individuals seem to have little
difficulty in achieving the RDA. But mere freedom from
deficiency disease is not at all the same thing as optimal
health. So the question must be: is there likely to be any
benefit in supplementing above the 100 mcg level, but below
the 400 mcg upper limit?
The answer appears to be a resounding yes. In addition to
ensuring the maximum possible supply of vital anti-oxidant
enzymes, research strongly suggests that supplementation at
the level of 200 mcg per day may act as a stimulant to the
immune system and may also help in the fight against
cancer, particularly that of the prostate.
Research published in the Journal of the American Medical
Association in 1996, although insisting that further
studies are needed, suggested that selenium supplements at
a level of 200 mcg a day may have a striking effect in
reducing certain common types of cancer, including those of
the prostate by 63%, oesophagus by 67%, colorectal by 58%
and lung by 46%.
Another study of 33,000 men over 5 years demonstrated a
2/3rds reduction in the risk of prostate cancer for men
taking 200 mcg a day (Journal of National Cancer Institute
1998), whilst a further study of 9,000 Japanese/American
men found a 50% reduction in the risk of developing
prostate cancer for those in the highest quartile of
selenium intake compared with those in the lowest quartile.
A useful working hypothesis may be that as cancer is
principally a disease of degeneration, it is the
acknowledged anti-oxidant effect of selenium that is
responsible for its apparent effectiveness in this area.
As always, however, the medical establishment is cautious,
and reluctant to confirm the potential benefits of
nutrition as opposed to more invasive, conventional
therapies. But the indications for selenium in relation to
prostate cancer, in particular, are so promising that a
number of large trials against placebo control are
currently in progress.
----------------------------------------------------
Steve Smith is a freelance copywriter specialising in
direct marketing and with a particular interest in health
products. Find out more at
http://www.sisyphuspublicationsonline.com/LiquidNutrition/In
formation.htm
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