Azara Blog: Vitamin D supposed to reduce risk of prostate cancer in men

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Date published: 2005/06/19

The BBC says:

Sunlight can reduce a man's risk of prostate cancer, a study suggests.

Researchers from three US centres found men exposed to a high amount of sun had half the risk of the disease than those exposed to a low amount.

Writing in Cancer Research, they suggest that the protection was a result of the body's manufacture of vitamin D after sun exposure.

But men were warned not to sunbathe excessively because of the risk of developing skin cancer.
...
Previous research has shown that the prostate uses vitamin D to promote the normal growth of prostate cells and to inhibit the invasiveness and spread of cancer cells to other parts of the body.

Genes determine how the body processes vitamin D. They control receptors which vary in their ability to bind to the vitamin and therefore influence the behaviour of cells.

DNA tests carried out by the researchers showed the risk of prostate cancer was reduced by up to 65% in men with certain gene variants.

Dr Esther John, of the Northern California Cancer Centre, who led the research, said: "We believe that sunlight helps to reduce the risk of prostate cancer because the body manufactures the active form of vitamin D from exposure to sunlight."

She added that if future studies continued to suggest this link, increasing vitamin D intake from food and supplements might be the safest solution to achieve the right levels.

Chris Hiley, head of policy and research at the Prostate Cancer Charity, warned that while increased exposure to sunlight might decrease the risk of prostate cancer, it also increased the risk of skin cancer.

"Men need more evidence-based research to know how to balance the risks and benefits."

Henry Scowcroft, of Cancer Research UK, also cautioned that more work was needed to weigh up the risks involved.

"For most people, it usually takes just a few minutes of sun exposure for your skin to make a very large amount of vitamin D," he added.

More rather pointless research. The algorithm for such research seems to be as follows. Take chemical C. If you do not like C then give huge quantities of it to test subjects and show that some bad effect E1 is more likely to occur. If you do like C then give normal quantities of it to test subjects and show that some good effect E2 is more likely to occur. Normally do not worry about confusing correlation and causation (which does not seem to be the problem here). And just consider effects in isolation, since that is the only way to get the black and white result you need in order to publish the results (well, to be fair, effects need to be considered in isolation but missing out the bigger picture in the discussion can lead to silly media coverage).

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