With over 40,000 new diagnoses of prostate cancer a year, it is the most common cancer in men in the UK. New research from Denmark (Outzen et al¹) has linked an increased risk of a high-grade aggressive form of prostate cancer to deficiencies in the mineral selenium.
Selenium is a micro-nutrient essential for human health, which helps to protect the body from the effects of damaging free radicals, as well as promoting a healthy immune system, playing an important role in thyroid function and helping to protect the body against the toxic effects of heavy metals.
Selenium can be found in small amounts in brazil nuts, red meats, egg yolks and seafood. However, evidence suggests that there is insufficient dietary intake of selenium in many European countries, including the UK, due to diminished levels found in soil, often as a result of continual or intensive farming. The deficiency is manifest upwards through the food chain via plants and animals, culminating in man. People also at risk of selenium deficiency include those with a restricted food intake (those on a diet, vegetarians, the elderly) or pregnant and lactating women.
The study which looked at blood selenium levels of circa. 81,000 men aged 50-64 years, also looked at the selenium-dependent enzyme, selenoprotein P. The research found found that higher levels of selenium and seleno-protein P were associated with a lower risk of high-grade disease. The finding correlates with other recent clinical studies linking selenium deficiency with increased risk of prostate cancer, including research conducted by scientists from Maastricht University Medical Centre in 2013₂ who found that men with high selenium levels in their blood had 63% lower risk of aggressive prostate cancer compared to men who had low selenium content.
The link between selenium deficiencies and cancer provides a rationale for selenium supplementation which is key for supporting the selenium-dependent proteins involved in normal immune function, a well-functioning thyroid gland and other selenium-dependent functions.
The most important issue regarding selenium supplements is that of bioavailability- the proportion of an oral supplement that is absorbed from the digestive tract into the bloodstream. Selenium supplements are available in several different chemical formulations, with differing bioavailability. The European Food Standards Authority (EFSA) recently approved the selenium supplement SelenoPrecise, containing an organic form of selenium (selenomethionine), as having up to ten times the bioavailability of inorganic selenium supplements. SelenoPrecise has been selected as the European reference compound for selenium supplements, and its efficacy and safety have been documented in a number of controlled clinical trials.
Findings of the study can be found in the British Journal of Nutrition.
1. Outzen, M., Tjønneland, A., Larsen, E. H., Friis, S., Larsen, S. B., Christensen, J., ... Olsen, A. (2016). Selenium status and risk of prostate cancer in a Danish population. British Journal of Nutrition, 1-9.
3. Geybels M et al (2013) Can selenium lower the risk of advanced prostate cancer? Data presented at American Association of Cancer Research, Washington VA.