New research which examined data from nearly 100 studies shows that vitamin D supplementation, when taken alone, does not reduce mortality among older adults. However, when examined by type of supplementation, the researchers did find that vitamin D3 alone reduced mortality by 11 per cent. The scientists stress that additional research is needed.
Previous research has shown that lower levels of vitamin D in the blood are associated with a number of different diseases. However, it was not clear whether vitamin D supplementation when given alone (that is, not co-adminstered with other interventions such as calcium) would reduce the risk of deaths from various causes. In order to help clarify these associations, researchers analysed the results of 73 observational cohort studies and 22 randomised trials of both naturally circulating vitamin D and supplements (either D2 or D3). In total, these studies involved nearly a million individuals from 26 countries and included patients with established cardiovascular disease as well as lower risk people without the disease.
The analysis reinforced the observational associations of lower levels of circulating vitamin D concentrations with deaths from cardiovascular, cancer, as well as other causes, but they also found that vitamin D supplements in the trials, overall, did not reduce the risk of all-cause mortality significantly.
However, when stratified by type of supplements, vitamin D3 taken alone reduced mortality significantly by 11% among older adults. By contrast, supplementation with vitamin D2 singly had no overall impact on mortality.
Remarking on the research, Dr Chowdhury said: “Before any recommendation of widespread supplementations with vitamin D3, it is essential that further clinical investigations are conducted into the optimal dosage and safety.”
Read more: http://www.cam.ac.uk/research/news/no-clear-evidence-vitamin-d-supplements-reduce-death-from-disease