Selenium cuts bowel cancer risk

Selenium is known for its cancer-combating properties, and an Australian study has shown how it could dramatically cut the incidence of bowel cancer.

The mineral is found in many foods including seafood, grains and eggs, and it is known to boost the body's antioxidant processes to play a range of other beneficial roles.

Professor Graeme Young says one such function is enhancing the triggering of "apoptosis" - a vital process that allows cells to kill themselves if they detect an error.

"When a cell realises that something has gone wrong it can trigger its own death so the cell doesn't become a problem," said Prof Young, head of the Flinders Centre for Cancer Prevention and Control at Adelaide's Flinders University.

"What the selenium does is just make the cell better at perceiving that it has to kill itself."

When Prof Young says problem he means cancer.

Tumours are masses of these rogue cells that no longer perform their ordinary function in the body and have also lost the ability to kill themselves off.

Selenium had yet another beneficial role, Prof Young said, as it was also thought to reduce damage to DNA-making cells less prone to "misbehaving" in the first place.

"When we put it all together, selenium looks a potentially useful agent when it comes to reducing our risk of getting a range of different cancers," he said.

A study last year by Prof Young showed that mice fed extra selenium had a 60 per cent reduced incidence of bowel cancer.

A follow-up study of 23 healthy people, aged over 50 who had extra selenium added to their daily milk, indicated a similar protective effect.

Both the mice and the human study participants had elevated levels of the powerful antioxidant (called GPx-2) in their gut, which Prof Young said was linked to their increased selenium intake.

"We think that activated GPx-2 in the bowel is what reduces the chance of getting cancer," he said.

Prof Young will present the results of this latest study at an expert summit - Australian Gastroenterology Week - which is underway in Sydney.

The recommended daily intake of selenium is 50 micrograms.

"(But) to get the benefit of protecting you against cancer it seems that you probably have to get close to 150 micrograms," Prof Young said, adding this was the equivalent of about four brazil nuts.

He also warned that in higher doses, selenium can be toxic.

"Our concern is that people often think that if a little bit of something is good for you, you should take a lot of it," Prof Young said.

"You could end up with selenium toxicity ... your hair falls our, your nails fall out, you get kidney problems and you can potentially get problems with glucose and insulin control too."