Vitamin D supplementation for prevention of mortality in adults
Meta-analysis of studies on vit-d supplementation and mortality
Vitamin D decreased mortality in all 56 trials analysed together
What level of supplementation would be optimal? (would need to look at specific papers to find this)
Insights, lessons learnt:
It is worth it to take vit-D. D3 is the only variant worth considering. Studies can vary wildly, hard to depend on any single result that has not been replicated or has a huge effect size and tiny p-values.
About 150 participants need to be treated over five years for one additional life to be saved - at maybe 3p/day, this is 8,212GBP to save a life. Possibly not the most efficient way to do this, but not bad in developed countries.
Vitamin D decreased mortality in all 56 trials analysed together (5,920⁄47,472 (12.5%) vs 6,077/47,814 (12.7%); RR 0.97 (95% confidence interval (CI) 0.94 to 0.99); P = 0.02; I2 = 0%). More than 8% of participants dropped out. ‘Worst-best case’ and ‘best-worst case’ scenario analyses demonstrated that vitamin D could be associated with a dramatic increase or decrease in mortality.”
“When different forms of vitamin D were assessed in separate analyses, only vitamin D3 decreased mortality (4,153⁄37,817 (11.0%) vs 4,340/ 38,110 (11.4%); RR 0.94 (95% CI 0.91 to 0.98); P = 0.002; I2 = 0%; 75,927 participants; 38 trials).”
” Vitamin D2, alfacalcidol and calcitriol did not significantly affect mortality. A subgroup analysis of trials at high risk of bias suggested that vitamin D2 may even increase mortality, but this finding could be due to random errors.”
“about 150 participants need to be treated over five years for one additional life to be saved.”
“Vitamin D3 also seemed to decrease cancer mortality, showing a reduction in mortality of 4 per 1000 persons treated for five to seven years.”