The role of cow's milk in preventing bowel cancer is set to be revealed through new research at Flinders University in Adelaide.
The university said it expected to have clear evidence by the end of the year on the role milk could play in boosting the anti-cancer properties of a natural trace element, selenium.
In a human trial already underway, Graeme Young is testing the beneficial impact of selenium when delivered through cow's milk compared with other forms of the dietary supplement.
Previous trials had confirmed that selenium in milk could lift levels of selenium in the blood.
Professor Young said chemical and yeast-based forms of selenium available over-the-counter as dietary supplements had 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," he 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."
In the current study involving 20 people researchers are comparing the milk form of selenium with a yeast-form of selenium and looking at how readily it gets absorbed.
"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," Prof Young said.
"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 properties of selenium relate to the way it encourages the body to rid itself of mutated cells that might otherwise become cancerous.
Previous research by the team from the 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.
Prof Young said the research was focussed 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 a benefit to become evident," he said.