Comparison 1. B vitamins versus placebo.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Overall cognitive function (MMSE)	3	488	Mean Difference (IV, Random, 95% CI)	0.44 [‐0.23, 1.12]
2 Episodic memory	3	397	Std. Mean Difference (IV, Random, 95% CI)	0.09 [‐0.10, 0.29]
3 Executive function	3	392	Std. Mean Difference (IV, Random, 95% CI)	0.03 [‐0.23, 0.29]
4 Speed of processing	2	173	Std. Mean Difference (IV, Random, 95% CI)	0.04 [‐0.26, 0.34]
5 Quality of life (D‐QOL)	1	138	Mean Difference (IV, Random, 95% CI)	0.0 [‐0.10, 0.10]
6 Functional performance (ADL)	1	75	Mean Difference (IV, Random, 95% CI)	‐0.78 [‐1.35, ‐0.21]