Middle-aged and elderly people with the lowest serum 25-hydroxyvitamin D concentrations were more likely than those with the highest levels to die from any cause within the next 16 years, an international team of researchers found.
People with a history of cancer also faced a poorer prognosis if they had lower levels of vitamin D.
But researchers conceded that more evidence from RCTs was needed before wider use of supplements other than in people with deficiency could be advised.
The meta-analysis published in the BMJ examined data from 26,018 men and women aged 50-79, obtained from eight cohort studies conducted in Europe and the US.
Data showed no clear trend of vitamin D levels by age, although average levels were lower among women.
During this time, there were 6,695 deaths among study participants, including 2,624 from cardiovascular disease and 2,227 from cancer.
People in the lowest quintile of vitamin D levels had the highest risk of cardiovascular death, whether or not they had previously had the disease. Those with low vitamin D levels also faced an added risk of dying from cancer if they had a history of the disease.
Researchers reported a dose-response relationship between low vitamin D levels and cancer deaths. They said the association between vitamin D levels and premature death was ‘remarkably consistent’ across countries, sexes, seasons in which blood was taken for samples, and age groups.
Study authors concluded: ‘Overall, this finding may support the view that low 25-hydroxyvitamin D concentrations might be a marker for a poor health status rather than a cause of premature mortality.’
They added that this link was plausible because people with poor health and reduced capacity for physical activity spend less time outdoors, limiting their production of vitamin D from exposure to sunlight.