Findings

What do systematic reviews say?

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Evidence found and GRADE certainty

1,966 questions · 3,201 findings · 165 reviews

No studies found 25 · 0.8%GRADE not reported 2,717 · 84.9%Very low 167 · 5.2%Low 124 · 3.9%Moderate 132 · 4.1%High 36 · 1.1%

Higher circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower circulating 25-hydroxyvitamin D (25(OH)D) concentration

Aggressive prostate cancer · Participants in observational studies

The meta-analysis of observational studies reported a OR of 0.88 (95% CI 0.68 to 1.15) for higher versus lower circulating vitamin D concentration.

1 finding from 1 review

Vitamin D vs placebo or control

Fasting blood glucose (mg/dL) · Adults with diabetes

Meta-analysis of randomised trials of vitamin D supplementation for Fasting glucose (Diabetes patients with normal glucose tolerance): WMD 0.01 (95% CI -0.21 to 0.23), not statistically significant. Umbrella review outcome-level evidence grade: Substantial effect unlikely.

2 findings from 1 review

Higher circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower circulating 25-hydroxyvitamin D (25(OH)D) concentration

Type 2 diabetes mellitus · Adults (general population)

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Type 2 diabetes: OR 0.63 (95% CI 0.56 to 0.69), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

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 vs placebo or control

Femoral neck bone mineral density (FN-BMD) · Older or community-dwelling adults

Meta-analysis of randomised trials of vitamin D supplementation for Bone mineral density in femoral neck, Community-dwelling adults: WMD 1.10 (95% CI 0.40 to 1.90), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

Vitamin D vs placebo or control

Lumbar spine bone mineral density (BMD) · Older or community-dwelling adults

Meta-analysis of randomised trials of vitamin D supplementation for Bone mineral density in lumbar spine, Community-dwelling adults: WMD 0.10 (95% CI -0.60 to 0.70), not statistically significant. Umbrella review outcome-level evidence grade: Substantial effect unlikely.

1 finding from 1 review

Higher circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower circulating 25-hydroxyvitamin D (25(OH)D) concentration

Sporadic colorectal adenoma recurrence · Adults (general population)

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Sporadic colorectal adenoma recurrence: OR 0.87 (95% CI 0.57 to 1.33), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Higher circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower circulating 25-hydroxyvitamin D (25(OH)D) concentration

Ischaemic heart disease · Adults (general population)

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Ischaemic heart disease: HR 0.72 (95% CI 0.65 to 0.81), statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D vs placebo or control

Non‐vertebral fractures · Older or community-dwelling adults

Meta-analysis of randomised trials of vitamin D supplementation for Fractures: non-vertebral, People aged >65 years: RR 0.79 (95% CI 0.63 to 0.99), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

Higher maternal circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower maternal circulating 25-hydroxyvitamin D (25(OH)D) concentration

Small‐for‐gestational age · pregnant women and their infants..

Meta-analysis of observational studies (higher vs lower maternal 25(OH)D) for Small for gestational age: OR 0.54 (95% CI 0.44 to 0.67), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

Higher circulating 1,25-dihydroxyvitamin D (1,25(OH)2D) concentration vs Lower circulating 1,25-dihydroxyvitamin D (1,25(OH)2D) concentration

Prostate cancer · Participants in observational studies

The meta-analysis of observational studies reported a OR of 0.99 (95% CI 0.87 to 1.12) for higher versus lower circulating vitamin D concentration.

1 finding from 1 review

Higher circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower circulating 25-hydroxyvitamin D (25(OH)D) concentration

Breast cancer · Adults (general population)

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Breast cancer (Premenopausal): RR 1.01 (95% CI 0.97 to 1.06), not statistically significant. Umbrella review outcome-level evidence grade: Substantial effect unlikely.

3 findings from 1 review

Higher circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower circulating 25-hydroxyvitamin D (25(OH)D) concentration

All cause mortality · people with chronic kidney disease (predialysis (GFR 15 to 60 mL/min/1.73 m²), HD, PD, transplant recipients)

Meta-analysis of observational studies (higher vs lower 25(OH)D) for All cause mortality, Patients with chronic kidney disease: RR 0.86 (95% CI 0.81 to 0.92), statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D vs placebo or control

Muscle strength · Older or community-dwelling adults

Meta-analysis of randomised trials of vitamin D supplementation for Performance measures: muscle strength, Older adults: SMD -0.19 (95% CI -0.35 to -0.02), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

Higher circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower circulating 25-hydroxyvitamin D (25(OH)D) concentration

Cognitive function · Adults (general population)

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Cognition: OR 0.42 (95% CI 0.34 to 0.53), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

Higher maternal circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower maternal circulating 25-hydroxyvitamin D (25(OH)D) concentration

Pre‐eclampsia · pregnant women and their infants..

Meta-analysis of observational studies (higher vs lower maternal 25(OH)D) for Pre-eclampsia: OR 0.56 (95% CI 0.39 to 0.80), statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin D vs placebo or control

Fractures: non-vertebral, non-hip · Older or community-dwelling adults

Meta-analysis of randomised trials of vitamin D supplementation for Fractures: non-vertebral, non-hip, Older women: OR 0.69 (95% CI 0.21 to 1.66), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Higher maternal circulating 25-hydroxyvitamin D (25(OH)D) concentration vs Lower maternal circulating 25-hydroxyvitamin D (25(OH)D) concentration

Head circumference (mm) · pregnant women and their infants..

Meta-analysis of observational studies (higher vs lower maternal 25(OH)D) for Head circumference: WMD 0.05 (95% CI -0.24 to 0.34), not statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

Vitamin D vs placebo or control

Diastolic blood pressure · Adults (general population)

Meta-analysis of randomised trials of vitamin D supplementation for Diastolic blood pressure: WMD -0.03 (95% CI -1.98 to 1.92), not statistically significant. Umbrella review outcome-level evidence grade: Suggestive.

1 finding from 1 review

Vitamin D vs placebo or control

Gestational age at birth (weeks) · pregnant women

Meta-analysis of randomised trials of vitamin D supplementation for Mean gestational age at delivery: WMD 0.17 (95% CI -0.16 to 0.51), not statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review