Experts find vitamin D ‘unimportant’ in terms of heart disease

Dundee experts’ results ‘seriously challenge’ views on deficiency

New research from Dundee University has shown vitamin D deficiency is not guilty when it comes to heart disease and winter deaths.

Research shows Dundonians get twice as much vitamin D in the summer as they do in the winter months, gaining the least in March.

Long thought to be associated with winter illness and death, new research has questioned that theory.

The research, led by Emeritus Professor Hugh Tunstall-Pedoe and published in the International Journal of Epidemiology, suggests that vitamin D is “unimportant” in cardiovascular disease and winter deaths, whatever its role in other diseases.

Vitamin D was first linked with excess winter disease in 1981, the same year that the cardiovascular epidemiology unit in Ninewells Hospital in Dundee was launched to study causes of the excess heart disease in Scotland.

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. Recently, their saved blood has been tested for vitamin D in Germany, in a Medical Research Council and European Commissionfunded international project.

Results were related to intervening illness and death. They 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. When these were balanced, vitamin D levels were found to have trivial or no additional effect and there was no increase in winter death levels.

Professor Tunstall-Pedoe, who initiated and still leads the Scottish Heart Health Study, said: “This is a major study, in a population with two-toone seasonal changes in vitamin D, and low levels overall.

“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.”

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. PROFESSOR HUGH TUNSTALL-PEDOE