Vitamin D deficiency may increase the risk of chronic headache, according to a recent study from the University of Eastern Finland.
The findings are published in Scientific Reports.
Researchers analyzed the serum vitamin D levels and occurrence of headache in approximately 2,600 men aged between 42 and 60 years in 1984-1989.
In 68% of these men, the serum vitamin D level was below 50 nmol/l, which is generally considered the threshold for vitamin D deficiency.
Chronic headache occurring at least on a weekly basis was reported by 250 men, and men reporting chronic headache had lower serum vitamin D levels than others.
When the study population was divided into four groups based on their serum vitamin D levels, the group with the lowest levels had over a 200% risk of chronic headache in comparison to the group with the highest levels.
Chronic headache was also more frequently reported by men who were examined outside the summer months of June through September.
Thanks to UVB radiation from the sun, the average serum vitamin D levels are higher during the summer months.
The study adds to the accumulating body of evidence linking a low intake of vitamin D to an increased risk of chronic diseases.
Low vitamin D levels have been associated with the risk of headache also by some earlier, mainly considerably smaller studies.