In a ground-breaking human trial now underway, a research team led by Professor Graeme Young is testing the beneficial impact that selenium delivered through cow's milk has in preventing bowel cancer compared with 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 South Australians, is trying to establish the extent to which the selenium is delivered to cells in the lining of the bowel for maximum effect.
Professor 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," Professor Young told Flinders Journal.
"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 the international journal Cancer Research - showed that selenium-enriched cow's milk produced a significant cancer preventing effect in mice.
The focus of the selenium research by the Flinders team is on prevention rather than the treatment of existing cancers.
"With the approach we are taking to prevention, you probably only need to achieve a slight, subtle effect with selenium for benefit to become evident," Professor Young said.
"We are looking for the preventative effect in healthy people - and also watching for any potential side-effects but, so far, have seen no evidence of any negative effects. We will have been able to have reached an initial conclusion as to the likely benefits of selenium by December this year."