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.
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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.
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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.
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"Fifteen hundred Americans die every year from [skin cancers]. Fifteen hundred Americans die every day from the serious cancers."
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