GPs should measure vitamin D frequently in high-risk patients, as low levels of the sunshine vitamin can double the risk of death from cardiovascular disease (CVD), say Austrian researchers.
The study involved 3,258 men and women, aged an average of 62 years. In all, 2.4 per cent of patients reported taking vitamin D supplements.
Fasting venous blood samples were taken from each partici-pant for 12 consecutive months to calculate average serum levels of the active version of vitamin D. Based on these findings, participants were divided into four groups.
Those in the lowest group had an average vitamin D level of 7.6ng/ml, compared with 28.4ng/ml for those in the highest quartile of vitamin D levels.
Participants were followed up for seven years, during which time 737 patients died, 62.8 per cent of them due to CVD.
Patients in the lowest vitamin D intake group were 2.08 times more likely to die from any cause and 2.2 times more likely to die from CVD than patients in the highest vitamin D group.
High levels of inflammatory marker C-reactive protein were also observed in those with the lowest vitamin D levels.
Lead researcher Dr Harald Dobnig, from the University of Graz, said high vitamin D levels may prevent death by lowering the risk of atherosclerosis but warned it was impossible to attribute the effects of vitamin D to one or two mechanisms.
'These results should prompt us to perform vitamin D measurements on a more frequent basis, especially in populations at high risk,' he said.
A 'generous approach' to vitamin D supplementation should be adopted, added Dr Dobnig.
Arch Intern Med 2008; 168: 1,340-8.