Can vitamins C or E improve fertility? Original paper

Reactive oxygen species can cause oxidative stress to sperm, and some evidence suggests that antioxidants can improve seminal parameters and fertility via reductions in oxidative stress. This meta-analysis assessed the effects of supplementing with two antioxidants — vitamin C and vitamin E — on seminal parameters, pregnancy rates, and adverse effects.

This meta-analysis included 11 randomized controlled trials assessing a total of 832 male participants. The primary outcomes were pregnancy rate, total sperm count, sperm concentration, progressive motility, and sperm morphology. The secondary outcomes were seminal volume, sperm vitality, and adverse events. The authors compared the participant outcomes among vitamin C, vitamin E, and control groups.

The trials were 4 to 48 weeks in duration. Three studies reported adverse effects, 6 assessed pregnancy rates, 3 assessed semen volume, 4 assessed total sperm count, 7 assessed sperm concentrations, 8 assessed progressive motility, 3 assessed sperm vitality, and 6 assessed sperm morphology.

The vitamin E group had an 86% higher pregnancy rate than the control group (there was insufficient evidence to assess vitamin C and pregnancy rates). In addition, both the vitamin C and vitamin E groups had greater improvements in progressive motility and total sperm count than control groups. Vitamin E (but not vitamin C) improved sperm concentration. Vitamin C (but not vitamin E) improved sperm vitality and sperm morphology. Neither vitamin affected semen volume. No adverse effects were reported.

The quality of evidence was moderate for progressive motility, sperm morphology, and total sperm number. The quality of evidence was low for pregnancy rates, semen volume, sperm concentration, and sperm vitality.

It's unclear whether the participants in the included studies had a vitamin C or vitamin E deficiency or insufficiency at baseline or whether the participants had elevated levels of reactive oxygen species in their semen at baseline.