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Vitamin D casts cancer prevention in new light Add to ...

For decades, researchers have puzzled over why rich northern countries have cancer rates many times higher than those in developing countries - and many have laid the blame on dangerous pollutants spewed out by industry.

But research into vitamin D is suggesting both a plausible answer to this medical puzzle and a heretical notion: that cancers and other disorders in rich countries aren't caused mainly by pollutants but by a vitamin deficiency known to be less acute or even non-existent in poor nations.

Those trying to brand contaminants as the key factor behind cancer in the West are "looking for a bogeyman that doesn't exist," argues Reinhold Vieth, professor at the Department of Nutritional Sciences at the University of Toronto and one of the world's top vitamin D experts. Instead, he says, the critical factor "is more likely a lack of vitamin D."

What's more, researchers are linking low vitamin D status to a host of other serious ailments, including multiple sclerosis, juvenile diabetes, influenza, osteoporosis and bone fractures among the elderly.

Not everyone is willing to jump on the vitamin D bandwagon just yet. Smoking and some pollutants, such as benzene and asbestos, irrefutably cause many cancers.

But perhaps the biggest bombshell about vitamin D's effects is about to go off. In June, U.S. researchers will announce the first direct link between cancer prevention and the sunshine vitamin. Their results are nothing short of astounding.

A four-year clinical trial involving 1,200 women found those taking the vitamin had about a 60-per-cent reduction in cancer incidence, compared with those who didn't take it, a drop so large - twice the impact on cancer attributed to smoking - it almost looks like a typographical error.

And in an era of pricey medical advances, the reduction seems even more remarkable because it was achieved with an over-the-counter supplement costing pennies a day.

One of the researchers who made the discovery, professor of medicine Robert Heaney of Creighton University in Nebraska, says vitamin D deficiency is showing up in so many illnesses besides cancer that nearly all disease figures in Canada and the U.S. will need to be re-evaluated. "We don't really know what the status of chronic disease is in the North American population," he said, "until we normalize vitamin D status."

Sunshine vitamin

For decades, vitamin D has been the Rodney Dangerfield of the supplement world. It's the vitamin most Canadians never give a second thought to because it was assumed the only thing it did was prevent childhood rickets, a debilitating bone disease. But the days of no respect could be numbered. If vitamin D deficiency becomes accepted as the major cause of cancer and other serious illnesses, it will ignite the medical equivalent of a five-alarm blaze on the Canadian health front.

For many reasons, Canadians are among the people most at risk of not having enough vitamin D. This is due to a quirk of geography, to modern lifestyles and to the country's health authorities, who have unwittingly, if with the best of intentions, played a role in creating the vitamin deficiency.

Authorities are implicated because the main way humans achieve healthy levels of vitamin D isn't through diet but through sun exposure. People make vitamin D whenever naked skin is exposed to bright sunshine. By an unfortunate coincidence, the strong sunshine able to produce vitamin D is the same ultraviolet B light that can also causes sunburns and, eventually, skin cancer.

Only brief full-body exposures to bright summer sunshine - of 10 or 15 minutes a day - are needed to make high amounts of the vitamin. But most authorities, including Health Canada, have urged a total avoidance of strong sunlight or, alternatively, heavy use of sunscreen. Both recommendations will block almost all vitamin D synthesis.

Those studying the vitamin say the hide-from-sunlight advice has amounted to the health equivalent of a foolish poker trade. Anyone practising sun avoidance has traded the benefit of a reduced risk of skin cancer - which is easy to detect and treat and seldom fatal - for an increased risk of the scary, high-body-count cancers, such as breast, prostate and colon, that appear linked to vitamin D shortages.

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