According to the study, people who live in sunny countries near the equator have only one-sixth of the age-adjusted incidence rate of pancreatic cancer as those who live far from it.
“The importance of sunlight deficiency strongly suggests — but does not prove — that vitamin D deficiency may contribute to the development of pancreatic cancer,” Garland noted.
Vitamin D is naturally produced by the body when the skin is directly exposed to sunlight. Limited foods also contain vitamin D. While fatty fish, such as salmon and tuna, are good sources, cheese and egg yolks provide small amounts.
The researchers studied data from 107 countries, taking into account international differences and possible confounders, such as alcohol consumption, obesity and smoking.
“While these other factors also contribute to risk, the strong inverse association with cloud-cover adjusted sunlight persisted even after they were accounted for,” Garland said.
As per the World Cancer Research Fund International, pancreatic cancer is the 12th most common cancer in the world.
Incidence rates are highest in North America and Europe; lowest in Africa and Asia.
The study appeared in the Journal of Steroid Biochemistry and Molecular Biology.