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 D vs placebo or no intervention

Cancer occurrence · 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 compared with placebo or no intervention (moderate certainty).

1 finding from 1 review

Staple food fortified with vitamin A plus other micronutrients vs no intervention

Subclinical vitamin A deficiency (serum/plasma retinol 0.70 μmol/L or less) · general population over 2 years of age

It is very uncertain whether staple food fortified with vitamin A plus other micronutrients changes subclinical vitamin A deficiency (serum/plasma retinol 0.70 μmol/L… compared with no intervention (very low certainty).

1 finding from 1 review

Staple food fortified with vitamin A plus other micronutrients vs same unfortified staple foods

Subclinical vitamin A deficiency (serum/plasma retinol 0.70 μmol/L or less) · general population over 2 years of age

Staple foods fortified with vitamin A plus other micronutrients probably leads to lower subclinical vitamin A deficiency (serum/plasma retinol 0.70 μmol/L… compared with same unfortified staple foods (moderate certainty).

1 finding from 1 review