Dr Kevin Fiscella from the University of Rochester led a study examining the risk of death from cardiovascular causes for individuals with low vitamin D levels. Mortality rates were studied in 2001 for 15,000 patients initially assessed between 1998 and 1994.

The researchers looked at the data on individuals in the bottom quarter of the sample in terms of levels of 25-hydroxyvitamin D (25[OH]D). They compared data from this group with others in terms of mortality from CHD, heart failure or stroke.

When other cardiovascular risk factors had been taken into account, those with low vitamin D levels had a 40 per cent higher chance of death from cardiovascular causes.

After adjusting for variations in vitamin D levels between black and white participants, the difference in risk for those with low vitamin D levels was not statistically significant.

Low vitamin D levels may precede the development of cardiovascular-related conditions, such as diabetes and hypertension, the researchers believe.

'Vitamin D may affect vascular endothelium directly through the renin-angiotensin axis; through effects on vascular smooth muscle, including cell proliferation, inflammation, and thrombosis; and through effects on hyperparathyroid hormone,' they said.

Whether vitamin D supplements would be able to reduce cardiovascular risk now needs to be assessed, they argue.

'Randomised controlled trials of vitamin D supplementation in those with low 25(OH)D levels are needed to determine whether optimisation of these levels improves outcomes from cardiovascular mortality, particularly among black people, who bear a disproportionate burden of cardiovascular disease.'

• Ann Fam Med 2010; 8: 11-8