People who reside at higher latitudes, with lower sunlight exposure and greater prevalence of vitamin D deficiency, are at a greater risk of developing leukaemia, a new global study has claimed.
Researchers at University of California (UC), San Diego in US found that persons residing at higher latitudes are at least two times at greater risk of developing leukaemia than equatorial populations.
They analysed age-adjusted incidence rates of leukaemia in 172 countries. The study followed similar investigations of other cancers, including breast, colon, pancreas, bladder and multiple myeloma.
In each study, they found that reduced sunlight/ultraviolet B (UVB) radiation exposure and lower vitamin D levels were associated with higher risks of cancer.
Leukaemia rates were highest in countries relatively closer to the poles, such as Australia, New Zealand, Chile, Ireland, Canada and US.
They were lowest in countries closer to the equator, such as Bolivia, Samoa, Madagascar and Nigeria.
“These results suggest that much of the burden of leukaemia worldwide is due to the epidemic of vitamin D deficiency we are experiencing in winter in populations distant from the equator,” said Cedric Garland from UC.
“People who live in areas with low solar ultraviolet B exposure tend to have low levels of vitamin D metabolites in their blood. These low levels place them at high risk of certain cancers, including leukaemia,” he added.
Few foods are natural sources of vitamin D, which is more abundantly produced when ultraviolet radiation from sunlight strikes the skin and triggers synthesis.
The findings were published in the journal PLOS One.