A ray of sunshine in the fight against cancer

It sounds too good to be true... a little inexpensive pill that could block the development of some cancers, strengthen bones, prevent multiple sclerosis and alleviate winter depression.

But it's not science fiction. The 'new aspirin' could be vitamin D. Just as we discovered that aspirin can guard against heart disease, vitamin D could become a useful weapon in the fight against MS, osteoporosis, mild depression and one of the most devastating diseases of our time - cancer.

'As time has gone by, vitamin D has raised its head as a sort of ambrosia for cancers,' says Dr Louise Parker, an epidemiologist and a world expert in the environmental exposures that can lead to cancer. Or, in the case of vitamin D, the lack of exposure.

'One of the most important sources of vitamin D is from the sun and through your skin,' says Dr Parker.

'Many parts of Canada don't get much sun in the winter. We've also been telling people to cover up and use sunscreen to prevent skin cancer. Sunscreen actually impairs your (skin's ability) to make vitamin D.'

So the Canadian Cancer Society recommends that during the winter, Canadians take at least 1,000 units a day of vitamin D, dubbed 'the sunshine vitamin.' Those units can be contained in a tiny pill that comes in a bottle of 100 tablets ranging from $5 to $10, depending on the brand name.

Dr Parker says 1,000 units a day is well beyond what you can obtain from your diet. Vitamin D is a bit of a rare vitamin, appearing only in fatty fish, cod liver oil and egg yolks. Even if you were to sunbathe in southern climates, you would not take in 1,000 units.

'If you were to lie naked on a beach in the Bahamas, and I don't recommend that because of skin cancer, you cannot get up to the equivalent of 1,000 units of vitamin D a day,' says Dr Parker.

She notes vitamin D as a factor is turning up in study after study. It turns out people with lung and colon cancer are vitamin D deficient. And it helps the body absorb calcium. In a study examining whether women who took vitamin D had a lower risk of osteoporosis, it was found the women taking vitamin D had stronger bones than those who did not take the vitamin. Years later, researchers went back to that study and found that the women who took vitamin D also had fewer cancers.

But before vitamin D becomes the 'new aspirin,' more research needs to be carried out.

Vitamin D works in very complicated ways, she says. It changes the way cells work. In fact, there is medical speculation that it may block cancer cell proliferation or improve immune system functions. But its role is not fully understood.

Lifestyle also has to be part of the equation. Dr Parker is looking at how obesity, which we know can cause cancer, and exercise, which we know prevents cancer, could interact with vitamin D.

'At the population level, I am trying to understand how all these things fit together,' says Dr Parker. 'It's very complex.'

Dr Parker describes it as looking for a piece of a jigsaw puzzle. 'We know some of the jigsaw pieces, but not all,' she says.

Meanwhile, there is very little evidence that taking vitamin D can harm you. Perhaps in huge doses it could cause kidney stones, but that has not been proven.

'On the average, 1,000 units a day is safe and is probably effective in reducing the risk of colon cancer, and maybe other cancers as well,' says Dr Parker.

So does she take vitamin D and recommend it? Absolutely.

'I take 1,000 units of vitamin D - one day on and one day off,' she says.