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‘It was already clear from earlier studies that a selenium deficiency may increase the risk of prostate cancer,’ says Dieuwertje Kok of Human Nutrition. ‘Now we looked at exactly what selenium does in the prostate, in order to find out how it could provide protection.’ The results were published in Oncotarget.
For the study, 23 men with (suspected) prostate cancer were randomly divided into two groups. One half were given 300 micrograms of selenium per day for five weeks, and the other half got a placebo. Then the researchers took samples of healthy prostate tissue from the participants. Kok: ‘Because we wanted to study the effect of selenium in relation to prevention of prostate cancer, we specifically looked at healthy tissue.’
In the group which was given selenium, the researchers saw a change in the activity of certain genes. These were mainly the genes which have an influence on the transformation of epithelial cells into mesenchymal cells. Kok: ‘Epithelial cells in the prostate are normally found all together in a row. Once they change into mesenchymal cells, they become ‘loose cannons’. They can start wandering and reach the circulatory system. This is a normal process which takes place, for instance, in embryonic development and in the healing of wounds. But in the case of prostate cancer, this transition to mesenchymal cells can lead to secondary tumours.’
According to Kok, selenium does not so much prevent prostate cancer from establishing itself as possibly curb its progress at a later stage. ‘Especially in aggressive forms of prostate cancer, selenium may prevent the cancer spreading. That is also what recent studies in the literature show, and we have revealed how this might work.’