Findings

What do systematic reviews say?

780 questions · 834 findings · 76 reviews

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No studies found 187 · 22.4%GRADE not reported 164 · 19.7%Very low 144 · 17.3%Low 172 · 20.6%Moderate 105 · 12.6%High 62 · 7.4%

A dose of vitamin D 4000 IU/d or more vs 3999 IU/d or less alone or with any other nutrient

Low birthweight · women during pregnancy

A dose of vitamin D 4000 IU/d or more showed no clear difference in low birthweight compared with 3999 IU/d or less alone or with any other nutrient (low certainty).

1 finding from 1 review

Regimens of vitamin D supplementation for women during pregnancy 2019 · Cochrane Headline outcomes only
RR 0.92 [0.49, 1.7]
2 studies · 1099 participants
Low

Vitamin D compounds (supplementation) vs placebo or control

Hypercalcaemia · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Risk of hypercalcaemia: RR 3.80 (95% CI 0.90 to 16.12), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 3.80 [0.90, 16.12]
5 studies · 382 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Subperiosteal erosions · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Subperiosteal erosions: RR 0.41 (95% CI 0.07 to 2.38), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 0.41 [0.07, 2.38]
3 studies · 120 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

All‐cause mortality · Adults with chronic kidney disease not requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Mortality: RR 1.40 (95% CI 0.38 to 5.15), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 1.40 [0.38, 5.15]
4 studies · 381 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Creatinine clearance · Adults with chronic kidney disease not requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Creatinine clearance: WMD -1.68 (95% CI -6.92 to 3.56), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
WMD -1.68 [-6.92, 3.56]
4 studies
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Risk of hyperphosphataemia · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Risk of hyperphosphataemia: RR 1.57 (95% CI 0.97 to 2.54), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 1.57 [0.97, 2.54]
2 studies · 59 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Fracture · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Fractures: RR 1.00 (95% CI 0.06 to 15.41), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 1.00 [0.06, 15.41]
4 studies
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Hypercalcaemia · Adults with chronic kidney disease not requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Risk of hypercalcaemia: RR 3.04 (95% CI 1.17 to 7.90), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 3.04 [1.17, 7.90]
7 studies · 612 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Parathyroid hormone · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Parathyroid hormone: WMD -196.05 (95% CI -298.43 to -93.66), statistically significant. Umbrella review outcome-level evidence grade: Probable.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
WMD -196.05 [-298.43, -93.66]
6 studies
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Risk of requiring dialysis · Adults with chronic kidney disease not requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Risk of requiring dialysis: RR 0.76 (95% CI 0.36 to 1.62), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 0.76 [0.36, 1.62]
4 studies · 245 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Parathyroid hormone · Adults with chronic kidney disease not requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Parathyroid hormone: WMD -49.34 (95% CI -85.70 to -12.97), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
WMD -49.34 [-85.70, -12.97]
4 studies
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Vascular calcification · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Vascular calcification: RR 1.09 (95% CI 0.45 to 2.67), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 1.09 [0.45, 2.67]
2 studies · 128 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

All‐cause mortality · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Mortality: RR 1.34 (95% CI 0.34 to 5.24), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 1.34 [0.34, 5.24]
5 studies · 477 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Alkaline phosphatase · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Alkaline phosphatase: WMD -27.35 (95% CI -50.69 to -4.01), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
WMD -27.35 [-50.69, -4.01]
3 studies
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Parathyroidectomy · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Parathyroidectomy: RR 0.82 (95% CI 0.05 to 12.47), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 0.82 [0.05, 12.47]
2 studies · 233 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Alkaline phosphatase · Adults with chronic kidney disease not requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Alkaline phosphatase: WMD -21.81 (95% CI -40.39 to 3.22), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
WMD -21.81 [-40.39, 3.22]
2 studies
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Risk of hyperphosphataemia · Adults with chronic kidney disease not requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Risk of hyperphosphataemia: RR 1.58 (95% CI 0.47 to 5.30), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 1.58 [0.47, 5.30]
2 studies · 245 participants
GRADE not reported

Vitamin D compounds (supplementation) vs placebo or control

Bone pain · Adults with chronic kidney disease requiring dialysis

Meta-analysis of randomised trials of vitamin D supplementation for Bone pain: RR 0.29 (95% CI 0.03 to 2.63), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational… 2014 All outcomes
RR 0.29 [0.03, 2.63]
4 studies · 109 participants
GRADE not reported

Any intermittent iron regimen (with or without other vitamins and minerals) vs daily regimen (with same vitamins and minerals)‐maternal outcomes

Low birthweight · Women receiving supplements in pregnancy

Any intermittent iron regimen (with or without other vitamins and… showed no clear difference in low birthweight (less than 2500 g) compared with daily regimen (with same vitamins and minerals)‐infant outcomes (low certainty).

1 finding from 1 review

Intermittent oral iron supplementation during pregnancy 2015 · Cochrane Headline outcomes only
RR 0.82 [0.55, 1.22]
8 studies · 1898 participants
Low

Any intermittent iron regimen (with or without other vitamins and minerals) vs daily regimen (with same vitamins and minerals)‐maternal outcomes

Participants with at least some Side Effects · Women receiving supplements in pregnancy

It is very uncertain whether any intermittent iron regimen (with or without other vitamins and… changes side effects (any reported throughout intervention period) compared with daily regimen (with same vitamins and minerals)‐maternal outcomes (very low certainty).

1 finding from 1 review

Intermittent oral iron supplementation during pregnancy 2015 · Cochrane Headline outcomes only
RR 0.56 [0.37, 0.84]
11 studies · 1777 participants
Very low