In otherwise healthy adult men trying to conceive, what is the role of vitamin C in male infertility and what is the appropriate dosage and safety considerations?

Vitamin C for Male Infertility: Role and Dosage

Vitamin C supplementation at 1000 mg twice daily (2000 mg total) for 2 months may improve sperm parameters in infertile men, but current guidelines do not recommend routine antioxidant therapy because evidence for improving live birth rates remains conflicting and of low quality. 1, 2

Guideline Position on Antioxidant Therapy

• The European Association of Urology (2025) states that evidence for antioxidant therapy in male infertility is "still conflicting" 1
• A Cochrane systematic review of 61 studies (6264 men) showed that when high-risk-of-bias studies were removed, antioxidant therapy no longer demonstrated an increase in live birth rates 1
• The American Urological Association/American Society for Reproductive Medicine (2021) advises clinicians to inform patients that supplements have "questionable clinical usefulness" in treating male infertility 2
• Human Reproduction Update (2017) concluded that available data are insufficient to recommend antioxidant therapy for men with abnormal semen parameters 2

Evidence for Vitamin C Specifically

Despite guideline caution, research studies show potential benefits:

• Sperm count improvement: A 2006 trial of 13 oligospermic men showed vitamin C 1000 mg twice daily for 2 months increased mean sperm count from 14.3 to 32.8 × 10⁶/mL (p < 0.001) 3
• Motility enhancement: The same study demonstrated motility increased from 31.2% to 60.1% (p < 0.001) 3
• Morphology improvement: Normal sperm morphology increased from 43% to 66.7% (p < 0.001) 3
• DNA integrity: Combined vitamin C (1000 mg) and vitamin E (1000 mg) daily for 2 months reduced DNA fragmentation from 22.1% to 9.1% (p < 0.001) in 64 infertile men 4
• Pregnancy rates: A 2022 meta-analysis of 11 studies (832 patients) found vitamin E and C improved pregnancy rates (RR 1.86,95% CI 1.02-3.41) without adverse effects 5

Recommended Dosing Protocol (If Pursued)

If you choose to trial vitamin C despite limited guideline support:

• Dose: 1000 mg vitamin C twice daily (2000 mg total daily) 3
• Duration: Minimum 2 months (one full spermatogenic cycle is approximately 74 days) 3, 4
• Combination therapy: Consider adding vitamin E 1000 mg daily for enhanced DNA integrity protection 4
• Multi-antioxidant approach: Some studies used vitamin C 100 mg + vitamin E 12 mg + CoQ10 30 mg + zinc 8 mg + folic acid 400 mg daily + selenium 200 mg every other day 6

Critical Pitfalls to Avoid

• Do not delay proven fertility treatments while trialing antioxidants, as female partner age-related fertility decline continues 1
• Do not use antioxidants as monotherapy without addressing modifiable lifestyle factors first (weight loss, smoking cessation, exercise) which have stronger evidence 1
• Do not assume semen parameter improvement equals pregnancy: Only 7 of 48 antioxidant trials reported clinical pregnancy rates, and only 4 reported live births 2
• Do not ignore baseline evaluation: Obtain semen analysis, medical history, and physical examination before starting any supplement 1

Prioritize Evidence-Based Interventions First

Before considering vitamin C supplementation:

• Weight optimization: BMI 18.5-25 kg/m² through diet and exercise improves sperm parameters 1
• Smoking cessation: Complete tobacco cessation has established fertility benefits 1
• Physical exercise: Regular activity enhances sperm quality 1
• Screen for cardiovascular risk: Infertile men have higher cardiovascular mortality; address modifiable risk factors 1

Practical Algorithm for Decision-Making

1. Baseline assessment: Semen analysis, medical/reproductive history, physical exam 1
2. Address lifestyle factors: Weight, smoking, exercise for 3 months 1
3. Repeat semen analysis: If parameters remain abnormal after lifestyle modification 1
4. Consider vitamin C trial: 1000 mg twice daily for 2 months if patient requests and understands limited evidence 3
5. Reassess at 2-3 months: Repeat semen analysis; if no improvement or conception hasn't occurred after 12 months total, proceed to assisted reproductive technology 1

Safety Considerations

• No adverse effects were reported in trials using vitamin C 2000 mg daily 3, 5
• Vitamin C is water-soluble with low toxicity risk at therapeutic doses 7
• Combined antioxidant regimens (vitamin C + E + others) showed no adverse effects in meta-analyses 5