Vitamin D 2 (ergocalciferol), found in plants, is produced by ultraviolet B irradiation of ergosterol and can be consumed as a supplement or in fortified foods.

Vitamin D is a group of fat soluble vitamins responsible for intestinal absorption of calcium and phosphate. Supplementation with vitamin D 3 significantly reduces overall mortality among older adults however, before any widespread supplementation, further investigations will be required to establish the optimal dose and duration and whether vitamin D 3 and D 2 have different effects on mortality risk. However, for vitamin D 2 supplementation, increased risks of mortality were observed in studies with lower intervention doses and shorter average intervention periods.Ĭonclusions Evidence from observational studies indicates inverse associations of circulating 25-hydroxyvitamin D with risks of death due to cardiovascular disease, cancer, and other causes. The effects observed for vitamin D 3 supplementation remained unchanged when grouped by various characteristics. In randomised controlled trials, relative risks for all cause mortality were 0.89 (0.80 to 0.99) for vitamin D 3 supplementation and 1.04 (0.97 to 1.11) for vitamin D 2 supplementation. Subgroup analyses in the observational studies indicated that risk of mortality was significantly higher in studies with lower baseline use of vitamin D supplements. Results In the primary prevention observational studies, comparing bottom versus top thirds of baseline circulating 25-hydroxyvitamin D distribution, pooled relative risks were 1.35 (95% confidence interval 1.13 to 1.61) for death from cardiovascular disease, 1.14 (1.01 to 1.29) for death from cancer, 1.30 (1.07 to 1.59) for non-vascular, non-cancer death, and 1.35 (1.22 to 1.49) for all cause mortality. Study specific relative risks from 73 cohort studies (849 412 participants) and 22 randomised controlled trials (vitamin D given alone versus placebo or no treatment 30 716 participants) were meta-analysed using random effects models and were grouped by study and population characteristics. Study selection Observational cohort studies and randomised controlled trials in adults, which reported associations between vitamin D (measured as circulating 25-hydroxyvitamin D concentration or vitamin D supplement given singly) and cause specific mortality outcomes.ĭata extraction Data were extracted by two independent investigators, and a consensus was reached with involvement of a third. Objective To evaluate the extent to which circulating biomarker and supplements of vitamin D are associated with mortality from cardiovascular, cancer, or other conditions, under various circumstances.ĭesign Systematic review and meta-analysis of observational studies and randomised controlled trials.ĭata sources Medline, Embase, Cochrane Library, and reference lists of relevant studies to August 2013 correspondance with investigators. 10Cancer Epidemiology Unit, University of Oxford, Oxford, UK.9School for Policy Research, University of Bristol, UK.8National University of Singapore, Republic of Singapore.7Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, US.6Clalit Research Institute and Chief Physician’s Office, Clalit Health Services, Israel.5Centre for Chronic Disease Control, New Delhi, India.

4Pontifícia Universidade Católica do Paraná, Brazil.3Public Health Genomics Foundation, Cambridge, UK.2Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands.1Department of Public Health and Primary Care, University of Cambridge, Strangeways Research Laboratory, Cambridge CB1 8RN, UK.Francesca Crowe, nutritional epidemiologist 10,.Cristina P Baena, assistant professor 4,.Hassan Khan, cardiovascular epidemiologist 1,.Jessica C Kiefte-de-Jong, postdoctoral scientist 2,.Susmita Chowdhury, research associate 3,.Clare Oliver-Williams, PhD candidate 1,.Rajiv Chowdhury, cardiovascular epidemiologist 1,.

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