The cow could play a role in boosting the anti-cancer properties of the natural trace element, selenium, according to a new study. A team led by Graeme Young of Flinders University is testing the beneficial impact that selenium delivered through cow's milk has in preventing bowel cancer compared to other forms of the dietary supplement. The latest trial followed earlier research that confirmed selenium in cow's milk could lift levels of selenium in the blood. The current study, involving 20 healthy volunteers, is trying to establish the extent to which the selenium is delivered to cells in the lining of the bowel for maximum effect. Young said chemical and yeast-based forms of selenium available 'over-the-counter' as dietary supplements have varying degrees of absorption and impact on the body. "So those forms of selenium will differ in their capacity to change someone's antioxidant status and capacity to prevent cancer," Young said. "It just so happens that when you feed selenium to cows and they produce selenium-enriched milk, the selenium seems to be in a chemical form that is both highly absorbable into the body and also more effective in terms of preventing cancer," he said. "We are comparing the milk form of selenium with a yeast-form of selenium in this human study and looking to see how readily the selenium gets into the body. "We are also taking biopsies from the lining of the bowel to make certain that the selenium is being delivered to the cells lining the bowel. If we can establish that is occurring, then we will be more confident that selenium is going to regulate the cells lining the bowels in humans." The anti-cancer impact of selenium is achieved by the way in which it encourages the body to rid itself of mutated cells that might otherwise become cancerous. Previous research by the team from Flinders Centre for Cancer Prevention and Control, published in the June issue of Cancer Resarch, showed that selenium-enriched cow's milk produced a significant cancer preventing effect in mice.