The British Medical Journal published the results of a meta-analysis on June 17, 2014 which indicate having a higher level of vitamin D is associated not only with a lower risk of dying from any cause over follow-up, but also reduction in the risk of dying from cancer among those with a history of the disease.
Researchers analyzed data from seven cohorts belonging to the Consortium on Health and Ageing: Network of Cohorts in Europe and the United States plus participants in the third US National Health And Nutrition Examination Survey. Subjects were restricted to nonsmokers with enrollment serum 25-hydroxyvitamin D [25(OH)D] data available. Among 6,695 deaths that occurred over up to 15.8 years of follow-up, 2,624 were due to cardiovascular diseases and 2,227 to cancer.
For men and women whose serum vitamin D levels were among the lowest one-fifth of subjects, there was a 57% higher risk of dying from any cause in comparison with those whose levels were among the top fifth. Among those with the lowest vitamin levels who did not have a history of cardiovascular disease, the risk of cardiovascular mortality was 41% greater than subjects whose levels were highest, and for those with a history of the disease, the risk was 65% higher.
When the risk of dying from cancer was examined, a different picture emerged. While subjects with no history of cancer whose vitamin D levels were lowest had the same risk of dying as those whose levels were highest, for those with a history of the disease, the risk was 70% greater for those in the lowest vitamin D category, indicating that the vitamin may play a role in improving prognosis.
“Despite levels of 25(OH)D strongly varying with country, sex, and season, the association between 25(OH)D level and all-cause and cause-specific mortality was remarkably consistent,” Ben Schöttker and colleagues write. Future clinical trials will offer more information on the effect of vitamin D on mortality outcomes.