Findings

What do systematic reviews say?

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Evidence found and GRADE certainty

948 questions · 998 findings · 100 reviews · Headline outcomes only

No studies found 233 · 23.3%GRADE not reported 40 · 4%Very low 203 · 20.3%Low 271 · 27.2%Moderate 176 · 17.6%High 75 · 7.5%

Vitamin E + vitamin C vs placebo

Any adverse effects of vitamin supplementation sufficient to stop supplementation · pregnant women

Vitamin C and vitamin E showed no clear difference in any adverse effects of vitamin supplementation sufficient to stop… compared with placebo (moderate certainty).

1 finding from 1 review

Vitamin D vs placebo or no intervention

Cancer occurrence in trials using vitamin D₃ (cholecalciferol) · healthy participants or recruited among the general population; individuals diagnosed with a specific disease in a stable phase or with…

Vitamin D showed no clear difference in cancer occurrence in trials using vitamin D₃ (cholecalciferol) compared with placebo or no intervention (moderate certainty).

1 finding from 1 review

Vitamin D vs placebo or no intervention

Cancer mortality in trials using vitamin D3 (cholecalciferol) ( · healthy participants or recruited among the general population; individuals diagnosed with a specific disease in a stable phase or with…

Vitamin D may leads to lower cancer mortality in trials using vitamin D₃(cholecalciferol) compared with placebo or no intervention (low certainty).

1 finding from 1 review

Vitamin D vs placebo or no intervention

Adverse events ‐ Nephrolithiasis in trials using vitamin D3 combined with calcium · healthy participants or recruited among the general population; individuals diagnosed with a specific disease in a stable phase or with…

Vitamin D may leads to higher adverse events: nephrolithiasis in trials using vitamin… compared with placebo or no intervention (low certainty).

1 finding from 1 review

Vitamin C vs placebo

Incidence of pneumonia Defined as patient admitted to hospital with a diagnosis of pneumonia Dose: 2 g per day · school‐aged children (6 to 15 years) and marine corps recruits (mean age 18.5 years)

It is very uncertain whether vitamin C changes incidence of pneumonia Defined as patient admitted to hospital with… compared with placebo (very low certainty).

1 finding from 1 review

Vitamin C vs placebo

Adverse effects (urticaria) Defined as participants reporting urticaria (hives) Dose: 2 g per day · school‐aged children (6 to 15 years) and marine corps recruits (mean age 18.5 years)

It is very uncertain whether vitamin C changes adverse effects (urticaria) Defined as participants reporting… compared with placebo (very low certainty).

1 finding from 1 review

Vitamin D given to infants vs vitamin D given to lactating mothers

Vitamin D insufficiency: 25‐OH vitamin D < 50 nmol/L · term breastfed infants to prevent vitamin D deficiency and improve bone health

It is very uncertain whether vitamin D given to infants changes vitamin D insufficiency: 25‐OH vitamin D < 50 nmol/L compared with vitamin D given to lactating mothers (very low certainty).

1 finding from 1 review