A 2022 Cochrane review found a possible increase in live birth and rated that evidence very low certainty. The authors' own conclusion is that the evidence is inconclusive. The men in the trials were already at a fertility clinic.
If the chance of live birth with placebo or no treatment was 16% in these studies, the authors estimated 17% to 27% with antioxidants. Odds ratio 1.43, 95% confidence interval 1.07 to 1.91. Twelve trials, 1,283 men. Very low certainty. Cochrane, 2022, evidence current to February 2021.
The live-birth result
The Cochrane review Antioxidants for male subfertility was current to February 2021. For live birth, the odds ratio was 1.43, 95% confidence interval 1.07 to 1.91, from 12 randomized trials and 1,283 men. The authors rated that very low certainty.
They translated it into the range on the chart. If couples in those studies had a 16% chance of a live birth with placebo or no treatment, the chance with antioxidants was estimated at 17% to 27%. The bottom of that range is one point above the starting point. The top is a larger change. Very low certainty means the true value could sit outside the picture the chart draws.
Clinical pregnancy, and what was not shown
Clinical pregnancy looked stronger on a still-low rating: odds ratio 1.89, 95% confidence interval 1.45 to 2.47, from 20 trials and 1,706 men. Low certainty, not very low. If the starting chance in those studies was 15%, the authors put the antioxidant chance at 20% to 30%.
Miscarriage was not shown to increase. Mild stomach discomfort may. The review could not say which antioxidant was better than which other antioxidant, because too few trials compared the same pair. 'Antioxidant' in this review is a class, not a brand and not a single dose of CoQ10, vitamin E, or zinc.
Why the authors called it inconclusive
The methods problems were ordinary and serious: poor reporting of randomization, missing live-birth and pregnancy outcomes in many trials, unclear or high dropout, and small samples. The authors tell clinicians to advise couples that the evidence is inconclusive for those reasons.
A men's fertility vitamin that lists zinc, selenium, and CoQ10 can cite this review only in that qualified way. Citing the odds ratio and skipping 'very low certainty' is not a fair summary.
Who it does not cover
The men were subfertile, and the couples were attending fertility clinics. The review is not a result for men who have not had a fertility evaluation. It is also not a semen-analysis result for a specific product.
Sources
This note uses the published review.
This is general information, not medical advice. All research.