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Evidence found and GRADE certainty

87 questions · 90 findings · 34 reviews

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No studies found 18 · 20%GRADE not reported 11 · 12.2%Very low 12 · 13.3%Low 20 · 22.2%Moderate 14 · 15.6%High 15 · 16.7%

Vitamin C vs placebo

Mortality: all cancers · healthy male physicians, period: 1997 to 2007 and female health professionals, period: 1998 to 2005

Vitamin C showed no clear difference in mortality: all cancers compared with placebo (high certainty).

1 finding from 1 review

Vitamin A vs placebo

Mortality: lung cancer · healthy people and healthy male physicians

Vitamin A showed no clear difference in mortality: lung cancer compared with placebo (high certainty).

1 finding from 1 review

Vitamin A vs placebo

Mortality: all cancers · healthy people and healthy male physicians

Vitamin A showed no clear difference in mortality: all cancers compared with placebo (high certainty).

1 finding 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

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

All cause mortality · Adults (general population)

Meta-analysis of observational studies (higher vs lower 25(OH)D) for All cause mortality: HR 0.72 (95% CI 0.66 to 0.78), statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

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 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 C vs placebo

Mortality: lung cancer ‐ men · healthy male physicians, period: 1997 to 2007 and female health professionals, period: 1998 to 2005

Vitamin C showed no clear difference in mortality: lung cancer ‐ men compared with placebo (high certainty).

1 finding from 1 review

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

Cardiovascular mortality · Adults (general population)

Meta-analysis of observational studies (higher vs lower 25(OH)D) for Cardiovascular disease mortality: RR 0.55 (95% CI 0.36 to 0.85), statistically significant. Umbrella review outcome-level evidence grade: No conclusion.

1 finding from 1 review

Vitamin A vs placebo

Mortality: all causes ‐ smokers and asbestos workers · healthy people and healthy male physicians

Vitamin A leads to higher mortality: all causes ‐ smokers and asbestos workers compared with placebo (high certainty).

1 finding from 1 review