Summary of findings 3. Vitamin E + vitamin C compared to placebo for MCI.

Vitamin E + vitamin C compared to placebo for MCI
Patient or population: MCI Setting: community Intervention: vitamin E + vitamin C Comparison: placebo
Outcomes	Anticipated absolute effects* (95% CI)		№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with placebo	Risk with vitamin E + vitamin C
Incidence of dementia ‐ not measured	‐	‐	‐	‐
Overall cognitive function assessed with: MMSE (Iranian version) Scale from: 0 to 30 follow‐up: 12 months	The mean overall cognitive function was 26.6 points	MD 0.23 points higher (0.25 lower to 0.71 higher)	256 (1 RCT)	⊕⊝⊝⊝ VERY LOW 1 2 3	Due to very low‐quality evidence, we cannot be sure of any effect of vitamin C + vitamin E on overall cognitive function.
Episodic memory ‐ not measured	‐	‐	‐	‐
Executive function ‐ not measured	‐	‐	‐	‐
Speed of processing ‐ not measured	‐	‐	‐	‐
Quality of life ‐ not measured	‐	‐	‐	‐
Mortality ‐ not reported	‐	‐	‐	‐
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; RR: Risk ratio; OR: Odds ratio;
GRADE Working Group grades of evidence High certainty: We are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

¹ Downgraded due to risk of bias. Unclear risks of selection, performance, and attrition bias.

² Downgraded due to indirectness. Inadequate definition of MCI.

³ Downgraded due to imprecision. Result from a single small study.

^{MCI: Mild cognitive impairment
 MMSE: Mini‐mental state examination}