Lead author Dr Kevin Fiscella said a complex host of genetic and lifestyle factors among blacks may explain why this population group has lower vitamin D levels across the lifespan than other races.

He said that people get vitamin D through their diets, sun exposure, and oral supplements.

Genetic factors common to blacks sometimes preclude vitamin D absorption, such as a higher incidence of lactose intolerance, which can eliminate vitamin-D fortified milk from the diet, and darker skin pigment that significantly reduces vitamin D synthesis.

“Therefore, our study suggests that the next step would be to intervene to boost vitamin D levels safely, with supplements,” said Fiscella, a national expert on disparities in health care and a professor of Family Medicine and Community and Preventive Medicine at URMC.

During the study, Fiscella and colleagues studied a sample of more than 15,000 American adults.

When they adjusted the statistics to look at race, blacks had a 38 percent higher risk of death than whites.

As vitamin D levels rose, however, the risk of death was reduced.

The same was true when researchers analysed the effect of poverty on cardiovascular death rates among blacks, which suggests that vitamin D deficiency and poverty each exert separate risk factors.