New research linking low vitamin D levels with deaths from heart disease and other causes bolsters mounting evidence about the “sunshine” vitamin's role in good health.
Patients with the lowest blood levels of vitamin D were about two times more likely to die from any cause during the next eight years than those with the highest levels, the study found. The link with heart-related deaths was particularly strong in those with low vitamin D levels.
Experts say the results shouldn't be seen as a reason to start popping vitamin D pills or to spend hours in the sun, which is the main source for vitamin D.
For one thing, megadoses of vitamin D pills can be dangerous and skin cancer risks from too much sunshine are well-known. But also, it can't be determined from this type of study whether lack of vitamin D caused the deaths, or whether increasing vitamin D intake would make any difference.
Low vitamin D levels could reflect age, lack of physical activity and other lifestyle factors that also affect health, said American Heart Association spokeswoman Alice Lichtenstein, director of the Cardiovascular Nutrition Laboratory at Tufts University.
Still, she said, the study is an important addition to an emerging area of research.
The study led by Austrian researchers involved 3,258 men and women in southwest Germany. Participants were aged 62 on average, most with heart disease, whose vitamin D levels were checked in weekly blood tests. During roughly eight years of follow-up, 737 died, including 463 from heart-related problems.
According to one of the vitamin tests they used, there were 307 deaths in patients with the lowest levels versus 103 deaths in those with the highest levels. Counting age, physical activity and other factors, the researchers calculated that deaths from all causes were about twice as common in patients in the lowest-level group.
The study's lead author, Dr. Harald Dobnig of the Medical University of Graz in Austria, said the results don't prove that low levels of vitamin D are harmful “but the evidence is just becoming overwhelming at this point.”
Scientists used to think that the only role of vitamin D was to prevent rickets and strengthen bones, Dobnig said.
“Now we are beginning to realize that there is much more into it,” he said