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, said 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.
Exactly how low vitamin D levels might contribute to heart problems and deaths from other illnesses is uncertain, although it is has been shown to help regulate the body's disease-fighting immune system, he said.
Earlier this month, the same journal included research led by Harvard scientists linking low vitamin D levels with heart attacks. And previous research has linked low vitamin D with high blood pressure, diabetes and obesity, which all can contribute to heart disease.