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Diet
& Nutrition Selenium
Research
A
government report
A government report has revealed that most
people in the UK are not getting sufficient amounts of the trace element
selenium in their diet. According to the MAFF report Food Surveillance
Information Sheet No.51, the average consumption of selenium is currently
only 34 mcg per day which falls well short of the RNI (Reference Nutrient
Intake , formerly recommended daily allowance) set by the Government's
COMA report in 1991 which stated that the desired level for men is 75 mcg
and 60 mcg for women.
These low levels could have serious
implications on our health. Selenium is a vital nutrient required to
activate thyroid hormone and for the production of the antioxidant enzyme
glutathione peroxidase, and there is accumulating evidence linking low
levels of selenium with cancer.
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Research carried out across the USA
Research carried out across the USA found
that those states with low levels of selenium in the soil had the highest
incidents of cancer, whereas those States with high levels of selenium in
the soil had the lowest rates of cancer.
Archives of Environmental Health
September/October 1988
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Research
from Finland
A study undertaken at the
University of Tampere, Finland provided further evidence. Blood
samples taken from over 20,000 men were frozen and compared 11 years later
with the mens' medical records. The researchers found that the men who
developed lung cancer had had low levels of selenium in their blood and
overall, it was found that men with the lowest levels of selenium were
more than three times likely to develop lung cancer than those with high
levels of selenium. The researchers concluded that "poor selenium
nutrition is a highly significant factor for lung cancer".
Kneckt P et al. 'Selenium Deficiency and Increased Risk of Lung
Cancer' Abstract of paper read at the Fourth International Symposium on
Selenium in Biology and Medicine, Tubingen. West Germany. July 1988.
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Skin
cancer and selenium
In West Germany, researchers found a link
with skin cancer and low levels of selenium. 101 patients with skin
cancer were examined at the University of Bonn and blood selenium levels
were compared with a control group of healthy people. The researchers
found that skin cancer patients had significantly lower levels of selenium
and concluded that low levels of selenium preceded the onset of skin
cancer and may even have contributed to its cause.
Selenium is found in garlic, brewers yeast,
wheat, mushrooms, sesame seeds, brazil and cashew nuts and asparagus but
the amount that the foods contain is entirely dependent upon the richness
of the soil. The Society for the Promotion of Nutritional Therapy is
leading a campaign for immediate and urgent action to be taken by the UK
government.
Reinhold U et al. 'Selenium Deficiency and Lethal Skin Cancer'.
Abstract of paper read at the Fourth International Symposium on Selenium
in Biology and Medicine, Tubingen. West Germany. July 1988.
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First double-blind, placebo controlled
study on Selenium: For years now, it has been known that those people who
have low serum selenium levels are more vulnerable to cancer. Selenium’s
main role in health care is regarded as being an important antioxidant - a
precursor of the antioxidant enzyme called ‘glutathionperoxidase’ (GSHpx)
- which protects cells from free radical damage. The evidence linking lack
of selenium with cancer is found not only in epidemiological studies, but
also from clinical studies. In fact, low dietary selenium levels have become
an accurate way of predicting future cancer rates. An American study,
published in the Journal of the American Medical Association (JAMA) (1)
showed that selenium supplementation led to a 50% reduction in cancer
mortality. This was the first double-blind, placebo-controlled study to show
such a drastic effect of selenium supplementation to the diet.
the study was carried out on 1,312 patients aged
between 18 - 80 years and diagnosed with skin carcinoma from seven
dermatological clinics in the USA. The aim of the study was to determine
whether daily selenium supplementation could prevent skin cancer from
recurring, and although the results did not support this contention, the
researchers did discover that cancer rates (including colorectal, prostate
and lung) were significantly lower in the patients taking selenium
supplements than in the placebo group.
The results revealed that there were 63% fewer cases
of colon cancer, 58% fewer cases of colorectal cancer and 46% fewer cases.
The total reduction in cancer mortality was found to be 50%, and there was a
37% decrease in cancer in general (all types).
Clark LC, Combs G.F.Jr, Turnbull BW et
Al. Effects of Selenium supplementation for cancer prevention in patients
with carcinoma of the skin. JAMA 1996, 276: 1957-63
Low
dietary Selenium levels linked to increase in cancer
The College and School of Public health and the National Taiwan University
have been conducting experimental research which has linked a low dietary
selenium intake with increased cancer. They studied the association
between plasma selenium levels and risk of liver cancer in chronic
carriers of hepatitis B and/or C virus.
Blood was drawn from 7,342 men in Taiwan between
1988- 92. Cases were followed-up for an average of 5.3 years, during which
time plasma selenium levels were measured using hydride atomic absorption
spectrometry. Of the 69 HCC (hepatocellular carcinoma) men who tested
positive for hepatitis B and/or hepatitis C and for the 139 healthy
patients, who were positive for hepatitis C viral antigens, the results
showed that average selenium levels were significantly lower in the liver
cancer cases than in the hepatitis-positive patients.
The research found a significant positive
correlation between plasma selenium levels and liver cancer which was most
notable in cigarette smokers and in men with low plasma levels of vitamin
A (and various cartotenoids).
YU
and colleagues, School of Public Health, College of Public Health,
National Taiwan University, Taipei Taiwan Yu MW et al. Plasma selenium
levels and risk of hepatocellular carcinoma among men with chronic
hepatitis virus infection. American Journal of Epidemiology 150(4):
367-74. 15 Aug 1999.
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This page was last updated on 25 October 2006 15:44:38
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