"For now, the vitamin D story is intriguing," said Naveed Sattar, a professor of metabolic medicine at the University of Glasgow in Scotland, who co-wrote an editorial accompanying the studies.
But more research is required before any definitive recommendations should be made, he
said, since "there may yet be unexpected risks to supplementation."
The 11 percent reduction in the death rate "seems remarkable," Sattar
and a colleague wrote in their editorial.
In an interview, he
said the reduction is "huge," potentially putting vitamin D deficiency in the same health-harming league as smoking and physical inactivity.
However, the studies are relatively small and mostly look at the elderly, Sattar
The whole picture is complicated, he
"There is an assumption that low blood vitamin D levels are causing or contributing to risk for many diseases but recent research tells us that, in fact, the opposite is the case and that having the disease in first place leads to people having low vitamin D levels," he
"Furthermore, many of the risk factors which cause disease -- namely, obesity, smoking and poor diet, can also lower vitamin D levels, and it is these risk factors and not necessarily the low vitamin D we need to correct," Sattar
"To resolve these issues, we need big trials to tell us once and for all whether vitamin D supplements make any difference to health."
When it comes to taking vitamin D supplements, "the best advice is to wait for study findings to be reported," a process that should only take a few more years since a big study will be finished by 2017, he