A belief that a lack of sunshine caused increased heart disease and deaths through a deficiency in vitamin D has been challenged by Scottish scientists.
Research from the University of Dundee, led by emeritus Professor Hugh Tunstall-Pedoe, suggests that vitamin D in not important in cardiovascular disease and winter deaths.
Vitamin D was first linked with excess winter disease in 1981, and thousands of healthy men and women agreed to have risk factors measured, blood taken for testing, and their medical records followed in the Scottish Heart Health Study.
Their saved blood was recently tested and it was found that 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.
When these were corrected for, vitamin D levels had a trivial or no additional effect, and people with low vitamin D levels did not have a greater increase in winter disease rates compared to others.
Professor Tunstall-Pedoe said: “If vitamin D deficiency were a major cause of heart disease and death, we would have expected it to show up. But it did not. So our results seriously challenge its alleged role.
“We want others to explore seasonal change as we have done – a huge natural experiment which comes for free.”
Professor Jeremy Pearson, associate medical director at the British Heart Foundation, which part funded the research, 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.
“The long-term Scottish Heart Health Study, which the BHF helped to fund, has provided a series of valuable insights over the years and they have now shown that that low vitamin D is result of other risk factors, rather than a cause of increased risk.”