The research was like a giant jigsaw puzzle with thousands of pieces Nevertheless, piece by piece connections were made and the jigsaw began to fit together. According to one school of thought, MS is a hereditary disease of northerners, possibly borne round the world by Vikings Researchers rushed to find the MS gene. But now Australians, who over the years have received the most dire warnings to keep out of the sun, have found that MS is six times less common in tropical Queensland than it is in Tasmania which has much less sun, particularly in winter. The research was like a giant jigsaw puzzle with thousands of pieces. But many important pieces were missing, and thousands of pieces from other jigsaws were muddled up in the same box. Perhaps, they proposed, the diseases were caused by viruses? People in the north eat more fat, perhaps that was causing these diseases? Maybe it was all a matter of heredity. While Parkinson's disease, another nervous disorder (causing primarily tremor and stiffness), had a similar geographical distribution.Theories abounded Sunlight was too obvious an answer for many researchers. Nor did anyone dare suggest that such different nervous diseases as schizophrenia, Parkinson's disease and MS might all have the same ultimate cause. Deaths from cancer of the colon and cancer of the prostate were found to be most frequent in the same countries where deaths from MS are most often seen. These were the least sunny northern countries of Europe and the least sunny northern states of the US. Dental decay and rickets were also found to be most common in these areas. And strangest of all, schizophrenia, an extremely disabling mental illness, was found to be more common in the colder northern states of America and in colder northern districts of Italy. Winter sunshine, which we now know can make a crucial difference to vitamin D stores, was implicated But Acheson's ideas fell on stoney ground.
"Sunshine? More like moonshine, what absolute poppycock," one senior colleague remarked in a public put down. It was an idea before its time and the work remained a curiosity, largely forgotten until now.Over the next 40 years several quite different diseases were found to be linked geographically with MS. Many studies have since shown that MS is more common in cold northern latitudes than it is in sunnier places. In a pioneering study in the 1960s, Professor Sir Donald Acheson, now Dean of Southampton Medical School, found that MS in US war veterans was most closely related to the amount of December sunlight in their place of birth. That adds up to some 20,000 cancer deaths a year in the UK resulting from too little exposure to the sun, compared with only 2,000 deaths per year from skin cancer of all kinds - not all of which are caused by too much sun. Melanoma, the commonest skin cancer (1,600 deaths per year) may also be caused by diet, overweight and lack of exercise.Multiple sclerosis is almost unknown in Europeans who are born in South Africa and so in the old days, when doctors worried about the rigours of weather, people with MS were often advised to move to a sunnier climate. And these extra cancer deaths, he points out, would exceed all the deaths from skin cancer put together. In the UK about 14,000 women a year die of breast cancer - some 40 per cent of these may be caused by deficiency of vitamin D, estimates William Grant, a NASA scientist who has become an expert in vitamin D epidemiology. He calculates that 12-15% of all cancers in the UK, apart from lung cancer, are linked to vitamin D deficiency. However in the British Isles with our long winters and cloudy summers, it seems that insufficient exposure to the sun can make the difference between illness and health, between life and death.Dr Peter Selby, lecturer in medicine at Manchester Royal Infirmary, says: "Reducing exposure to solar radiation, far from preventing cancer, may have the opposite effect." He points out that a 10 per cent decrease in exposure to sunlight would not greatly reduce skin cancer but could lead to a 6 per cent increase in certain other cancers. In part this is because vitamin D is not the only trigger for these diseases. And it's all down to a deficiency of vitamin D - some 90 per cent of which we get from sunlight.Most medical researchers have been slow in recognising the potentially lethal consequences of vitamin D deficiency. But what if the advice we've been given is wrong? What if hiding your skin from the sun is putting your health in danger? How many times have you heard it: "There's no such thing as a healthy tan." Second only to "smoking kills", avoiding the sun is the health advice that has most permeated our conciousness. |
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