Scientists have claimed that a lack of exposure to sunshine resulting in a vitamin D deficiency may not play a key role in heart disease and winter deaths.
A research team from the University of Dundee found that while low vitamin D levels correlates with higher levels of cardiovascular disease the cause was likely to be down to lifestyle and other risk factors.
Researchers examined blood samples taken from thousands of men and women who agreed to have their risk factors measured after vitamin D was first linked with excess levels of winter disease in 1981.
Prof Jeremy Pearson, British Heart Foundation said, "We've known for many years that a low level of vitamin D is associated with an increased risk of cardiovascular disease, but it was not clear whether lack of vitamin D directly causes the increased risk or is a consequence of other factors."
Results show that while overall incidence of cardiovascular events did not vary seasonally, deaths from heart disease and from other causes did.
Vitamin D levels also varied, with highest levels seen in August and lowest in March - a two-to-one difference - but crucially this was several weeks after peak winter death rates, so changes in vitamin D were too late to be the cause.
People with lower vitamin D levels did have higher rates of cardiovascular disease, but low vitamin D levels were also associated with lifestyle and other risk factors.