Table 4. Treatment effect of individual antioxidants on erectile function among included studies.

Antioxidant	Studies	IIEF-EF	95% CI	p-value
		Mean difference
Pycnogenol	5	9.2	6.9 to 11.5	<0.001
L-carnitine	3	7.4	-0.8 to 15.7	0.08
L-arginine	7	6.7	3.9 to 9.5	<0.001
Other antioxidants	4	5.7	0.0 to 11.5	0.05
Ginseng	7	2.9	1.5 to 4.4	<0.001
Vitamin E	2	0.4	-1.3 to 2.0	0.67

IIEF-EF: International Index of Erectile Function-Erectile Function, CI: confidence interval.