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Selenium and Cancer Prevention and Research

The beneficial effect of selenium has been noted in China where the amount of selenium in the soil and therefore in the food varies across the country from too low to OK to quite high. A statistical corrrelation between the amount of selenium in food and the incidence of cancer has been noted. The flour in South Dakota, North Dakota, Montana and Wyoming in the USA has a high amount (about 100 ug/100 grams) and a lower cancer incidence has been noted. 
Two studies have shown that there is a correlation between lower blood plasma selenium levels and incidence of cancer. One of these studies found that men with low selenium in their plasma had a four to five times higher risk of developing prostate cancer.  
Flour contains mostly protein, starch and fat. The selenium is found in the various amino acids which join up to make protein.  Three amino acids ordinarily have a sulphur atom i.e. cystine, cysteine and methionine but the sulphur atom can be replaced by a selenium atom to give selenocystine, selenocysteine and selenomethionine.  Ingested protein is decomposed into its constituent amino acids in the gut which then pass into the blood stream. The selenium can be measured in the blood plasma. The organic forms of selenium such as selenomethionine are thought to be more effective than inorganic forms such as sodium selenite and sodium selenate.
The UK population consumed a significant quantity of bread, rich in selenium, in the 1950s due to imported North American wheat flour. The UK had at that time a lower incidence of cancer than today. By 1995, these wheat imports had fallen by 80% and daily dietary intake of selenium had fallen from 60 ug to 34 ug, well below the Recommended Nutrient Intake of 75 ug for men and 60 ug for women. Cancer incidence has increased when it was expected that it would decrease because of banning and removal of asbestos, banning of industrial cancer forming chemicals, more use of sunscreen. From 1971 to 2004, cancer incidence has increased from 140 501 to 241 601 per year. 
The recommended daily intake is 100 to 200 ug (The Encyclopedia of Vitamins, Minerals and Herbal Supplements by Dr. Sarah Brewer, published by Robinson in association with the Daily Telegraph) while Professor Margaret Rayman recommends 150 ug per day. People can take in selenium by eating flour and Brazil nuts. Health food shops sell food products containing selenium in organic form, selenomethionine. These products are tablets which can be swallowed as such or ground up in a mortar and pestle and added to flour, breakfast cereal etc. The tablets cost about 7 pence a day.
Marriages Organic wholemeal flour has 20 ug per 100 grams while Marriages Canadian flour has 50 ug per 100 grams and Shipton Mill organic Canadian white and wholemeal flour has 50 ug per 100 grams. You can use these to bake your own bread. Supermarket and premium brands have lower amounts (see table Selenium in foods)
Selenium has other possible benefits, i.e. it may enhance male fertility, decrease cardiovascular mortality and lower age related brain decline.

Book and Research Papers

THE PROSTATE CARE COOKBOOK by Professor Margaret Rayman. Published 2009 ISBN 978-1-85626-869-1
Prof. Margaret Rayman is Professor of Nutritional Medicine at the University of Surrey.
Selenium exerts its anticarcinogenic effect by multiple mechanisms. In the physiological range, selenium appears to function as an antimutagenic agent, preventing the malignant transformation of normal cells and the activation of oncogenes.  These protective effects seem to be primarily associated with its presence in glutathione peroxidases which are known to protect DNA and other cellular components from damage by oxygen radicals. Selenoenzymes are also known to play roles in carcinogenic metabolism, in the control of cell division, oxygen metabolism, detoxification processes, apoptosis induction and the functioning of the immune system.  Other modes of action, either direct or indirect, may also be operative such as the partial retransformation of tumor cells and the inactivation of oncogenes. However, the effects of selenium in the physiological dosage range are not attributable to cytotoxicity, allowing selenium to be defined as a genuine nutritional cancer protecting agent. The anticarcinogenic effects of selenium are counteracted by selenium antagonistic compounds and elements. For maximum utilisation of its cancer-protective potential, selenium supplementation should start early in life and be maintained over the entire life span. In addition, exposure to selenium antagonists and carcinogenic risk factors should be minimised by appropriate dietary and lifestyle changes.
Author: Professor G.N Schrauzer, Professor of Chemistry, University of California, U.S.A.   Published in the journal: Cellular and Molecular Life Sciences  (2000)  Vol. 57  pp.1864-1873.                             
LATEST RESEARCH PAPERS. Selenium and selenium-antagonistic elements in nutrutional cancer prevention.  G.N.Schrauzer. Critical Reviews in Biotechnology. 2009. Volume 29 Pages 10-17.
You can get the complete research paper by asking your local library to get an abstract from a journal. They get it from the British Library.


British Journal of Nutrition Year 2008 volume 100  Pages 254-268
BRITISH JOURNAL OF NUTRITION  Year 2008 volume 100 Pages 238-253 
These papers can be seen on the Internet via Google. Choose MORE,  then choose SCHOLAR, choose ADVANCED SEARCH. Enter the details in the fields.  (http://journals.cambridge.org/article_S0007114508922522)
                                                                                           Peter Symonds  B.Sc. C.CHEM. M.R.S.C.
Apex Analytical,
Nov 1, 2010, 4:41 AM