A meta-analysis of seven previously published studies found that the minerals’s potential protective effect was seen mainly among women, which suggests gender-specific differences in selenium accumulation and excretion, according to findings published in Cancer Epidemiology, Biomarkers & Prevention.
“Results suggest a beneficial effect of high selenium intake for bladder cancer risk,” wrote the researchers, led by Dr Núria Malats, from the Genetic and Molecular Epidemiology Group at the Spanish National Cancer Research Center.
"The lower the levels of selenium, the higher the risk of developing bladder cancer," said Dr. Malats.
Essential nutrient
Selenium is an essential macronutrient, and is considered to be an antioxidant. High levels of selenium have been inversely associated with risk of developing several cancers, including bladder, prostate and thryroid .
Selenium has also been linked with a lower risk of skin cancer , but studies on lung cancer have suggested the nutrient ‘has no benefit’ .
Last year Bayer Healthcare had to change health claims about prostate cancer on its ‘One A Day’ vitamins, following threats of a lawsuit calling the claims “misleading”.
Inverse association
The analysis found overall risk of bladder cancer was inversely associated with levels of selenium.
A significant protective effect for selenium was seen mainly among women. The researchers suggest this may result from gender-specific differences in selenium accumulation and excretion.
“This meta-analysis supports an inverse association between selenium concentration and bladder cancer risk,” wrote the researchers.
Although the results suggest a protective effect of selenium for bladder cancer risk, the Dr. Malats warned that additional large-scale studies are warranted to support this preliminary evidence.
“More studies are needed to confirm these findings before an enforcement of high selenium intake is recommended," stated Malats.
Prof. Elizabeth A. Platz from Johns Hopkins Bloomberg School of Public Health, and editorial board member for Cancer Epidemiology, Biomarkers & Prevention said: "These findings provide a valuable lead for what to do next to understand if there is a role for selenium supplementation in bladder cancer prevention."
The researchers suggest further research is needed in to the relationship between selenium and bladder cancer, focusing especially on the dose-response relationship.
“Addressing this [dose-response] relationship is of public health importance for setting recommended daily intakes for selenium and for targeting subsets of the population for selenium supplementation”, added Prof. Platz.
Source: Cancer Epidemiology, Biomarkers & Prevention
Published online ahead of print, doi: 10.1158/1055-9965.EPI-10-0544
“Selenium and Bladder Cancer Risk: a Meta-analysis”
Authors: A.F.S. Amaral, K.P. Cantor, D.T. Silverman, N. Malats