Men who work outdoors, enabling their bodies to create vitamins through exposure to sunlight, had a reduced risk of kidney cancer researchers said this week.
In the largest study of its kind, scientists found that vitamin D — produced by the skin when exposed to ultraviolet (UV) light — was associated with a reduced rate of renal cancer of up to 73% among men.
However, the study, published by the American Cancer Society, found that the reduced risk applied only to men — there was no drop in renal cancer among women who worked outdoors, according to the study.
The researchers, from the National Cancer Institute in the United States, said the study of 2 500 workers in central Europe supported emerging evidence that the prevalence of a number of cancers — including breast, ovarian and colorectal — was lower when people were exposed to UV light.
They said vitamin D, a known anticarcinogenic, was carried by the body to the liver and on to the kidneys and recommended further research.
‘Scientific evidence suggests that vitamin D, which is generally made in the body after exposure to sunlight, may help prevent a number of diseases, including cancer,” said research author Sara Karami.
‘In our study we used job titles to estimate sunlight exposure at work. We observed that men with high estimated levels of sunlight exposure had a lower risk of kidney cancer than men who had lower estimated sunlight exposure at work.”
Scientists have monitored an increase in renal cell carcinoma (RCC), the main form of kidney cancer, in the US and globally in the past 20 years.
A reduction in vitamin D — probably caused by many more people having sedentary lifestyles and indoor jobs — is believed to be a contributory factor.
The researchers studied more than 2 500 workers of Caucasian descent in Russia, Romania, Poland and the Czech Republic, splitting them into three groups according to exposure to daylight in their jobs.
A significant fall of up to 38% in the risk of RCC was found with increasing occupat ional UV exposure among men. In the most northern regions a 73% fall was discovered.
But after finding no similar decrease in the risk for women, Karami said: ‘We do not have an explanation for the apparent differences in risk between men and women. Biological or behavioural differences between men and women may play a role.
‘For example, hormonal differences may influence the body’s response to sunlight exposure and men may be prone to working outdoors while shirtless.”
Although some foods cont a in vitamin D, the majority of people receive up to 90% of the vitamin through exposure to UV light.
Despite the findings, the researchers warned against ignoring the ‘well-documented risks” of skin cancer, which can result from from spending too much time in the sun without protection.