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Evidence found and GRADE certainty

1,126 questions · 1,225 findings · 111 reviews

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No studies found 235 · 19.2%GRADE not reported 260 · 21.2%Very low 207 · 16.9%Low 271 · 22.1%Moderate 177 · 14.4%High 75 · 6.1%

Vitamin C vs placebo

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

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

1 finding from 1 review

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

Adverse events: yellowing of the skin · healthy people and healthy male physicians

Vitamin A leads to higher adverse events: yellowing of the skin compared with placebo (high certainty).

1 finding from 1 review

Vitamin A vs placebo

Adverse events: minor gastrointestinal symptoms · healthy people and healthy male physicians

Vitamin A leads to higher adverse events: minor gastrointestinal symptoms compared with placebo (high certainty).

1 finding from 1 review

Vitamin A vs placebo

Incidence: all cancers · healthy people and healthy male physicians

Vitamin A showed no clear difference in incidence: all cancers 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

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

Vitamin C vs placebo

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

Vitamin C showed no clear difference in incidence: lung cancer compared with placebo (moderate certainty).

1 finding from 1 review

Vitamin C vs placebo

Incidence: 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 incidence: lung cancer ‐ men compared with placebo (high certainty).

1 finding from 1 review

Vitamin D vs placebo

Ulcer healing (absolute change in individual parameters of ulcer dimensions over time: mean (SD) cm wound length reduction · people with diabetes and foot ulcers

It is very uncertain whether vitamin D changes ulcer healing (absolute change in individual parameters of ulcer… compared with placebo (very low certainty).

1 finding from 1 review

Vitamin D vs placebo

Ulcer healing (absolute change in individual parameters of ulcer dimensions over time: mean (SD) cm wound depth reduction · people with diabetes and foot ulcers

It is very uncertain whether vitamin D changes ulcer healing (absolute change in individual parameters of ulcer… compared with placebo (very low certainty).

1 finding from 1 review

Vitamin D vs placebo

Ulcer healing (absolute change in individual parameters of ulcer dimensions over time: mean (SD) cm wound width reduction · people with diabetes and foot ulcers

It is very uncertain whether vitamin D changes ulcer healing (absolute change in individual parameters of ulcer… compared with placebo (very low certainty).

1 finding from 1 review