Researchers tested whether antioxidant supplements could help men improve their chances of having a baby. Over 1,100 men at fertility clinics in the Netherlands took either antioxidant pills or fake pills for 6 months while trying to conceive with their partners. The study found that the antioxidant pills didn’t work better than the fake pills—pregnancy rates were about the same in both groups. This large, well-designed study suggests that these popular supplements may not be worth taking for fertility purposes.

The Quick Take

  • What they studied: Whether antioxidant supplements (a mix of vitamins and minerals) could help men improve sperm quality and increase the chances of getting their partners pregnant.
  • Who participated: 1,171 men (average age 34) and their female partners (average age 32) who were trying to have a baby and visiting fertility clinics in the Netherlands. All couples were trying different fertility treatments like IVF or artificial insemination.
  • Key finding: After 6 months, about 34% of men taking antioxidants had partners who became pregnant, compared to 38% taking fake pills. This difference was not meaningful—basically the same success rate. Interestingly, when looking at months 4-6 specifically, the antioxidant group actually had slightly fewer pregnancies (15.5% vs 21.5%).
  • What it means for you: If you’re a man trying to conceive, antioxidant supplements like the one tested may not improve your chances of having a baby. Talk to your fertility doctor before spending money on these supplements, as this large study suggests they don’t help.

The Research Details

This was a randomized controlled trial, which is considered one of the best ways to test if a treatment works. Researchers recruited 1,171 men from 21 fertility clinics across the Netherlands between 2018 and 2024. Half the men received antioxidant pills containing vitamins and minerals (including zinc, B vitamins, and folic acid), while the other half received identical-looking fake pills. Neither the men nor the doctors knew who was getting the real pills or fake pills—this is called “blinding” and helps prevent bias. All men took their assigned pills daily for 6 months while receiving standard fertility care.

The researchers tracked whether the men’s partners became pregnant within 6 months and also measured sperm quality, sperm DNA damage, and other fertility markers. They used “intention-to-treat” analysis, meaning they counted all participants in their original groups even if some didn’t complete the study perfectly. This approach gives the most realistic picture of how the treatment works in real life.

This study design is important because it’s the gold standard for proving whether a treatment actually works. By randomly assigning men to groups and using fake pills for comparison, researchers can be confident that any differences between groups are due to the supplement itself, not other factors. The large number of participants (over 1,100) also makes the results more reliable than smaller studies.

This is a high-quality study because: (1) it was large with over 1,100 participants, (2) it was double-blinded so neither participants nor doctors knew who got the real supplement, (3) it was conducted at multiple clinics across a whole country, (4) it followed participants for a full 6 months, and (5) it was published in a major medical journal. The study was also registered before it started, which prevents researchers from changing their plans based on results. These features make the findings very trustworthy.

What the Results Show

The main finding was that antioxidant supplements did not improve pregnancy rates. In the antioxidant group, 33.8% of couples achieved an ongoing pregnancy within 6 months, compared to 37.5% in the placebo group. This 3.7 percentage point difference is not statistically significant, meaning it could easily have happened by chance. The researchers calculated that the antioxidant group was actually 15% less likely to achieve pregnancy, though this wasn’t proven with certainty.

When the researchers looked specifically at months 4-6 (when the supplement would have had the most time to affect sperm), they found something unexpected: the antioxidant group had significantly fewer pregnancies (15.5%) compared to placebo (21.5%). This suggests the supplement may have actually been slightly harmful during this window, though the reason is unclear.

The supplement tested contained a specific combination of ingredients: betaine, L-cystine, niacin, zinc, vitamin B6, vitamin B2, folic acid, and vitamin B12. Despite these being nutrients that sound beneficial, the combination didn’t help fertility outcomes.

The researchers also measured sperm quality (including count, movement, and shape), sperm DNA damage, fertilization rates, embryo quality, miscarriage rates, and ectopic pregnancy rates. None of these secondary measures showed significant differences between the antioxidant and placebo groups. This means the supplement didn’t improve sperm quality in measurable ways, even though that was one reason researchers thought it might help. The time it took couples to become pregnant was also similar between groups.

Many smaller studies have suggested antioxidants might help male fertility, which is why this supplement became popular. However, those studies often had design flaws or conflicting results. This large, well-designed trial provides stronger evidence that contradicts the optimistic findings from smaller studies. It suggests that when antioxidants are tested properly in large groups, they don’t actually deliver the promised benefits. This is a common pattern in nutrition research—initial promising results often don’t hold up in larger, better-designed studies.

While this is a strong study, it has some limitations worth noting. First, it only tested one specific antioxidant supplement formula, so results might differ with other brands or combinations. Second, the study only followed men for 6 months, so longer-term effects are unknown. Third, most participants were from the Netherlands and were relatively young (18-50 years old), so results might not apply to older men or different populations. Finally, the study didn’t measure whether men actually took all their pills as instructed, though this is common in supplement research.

The Bottom Line

Based on this study, doctors should not recommend antioxidant supplements to men trying to conceive, as there’s no evidence they help. Men seeking fertility care should focus on proven approaches: maintaining a healthy weight, avoiding smoking and excessive alcohol, managing stress, and following their fertility doctor’s treatment plan. If considering any supplements, discuss them with your fertility specialist first. The evidence from this large trial is strong (high confidence) that this particular antioxidant supplement doesn’t improve pregnancy chances.

This finding matters most for men trying to have a baby who are considering spending money on antioxidant supplements. It’s also relevant for their partners and fertility doctors who might recommend these supplements. However, this study doesn’t apply to men taking antioxidants for other health reasons unrelated to fertility. If you have specific health conditions, talk to your doctor before stopping any supplements.

The study measured effects over 6 months, which is the time it takes for new sperm to fully develop. If antioxidants were going to help, benefits should have appeared within this timeframe. You shouldn’t expect to see fertility improvements from this type of supplement even if you took it longer than 6 months, based on this evidence.

Want to Apply This Research?

  • If using a fertility tracking app, focus on tracking proven factors: daily weight, alcohol consumption, smoking status, sleep hours, and stress levels. Skip tracking antioxidant supplement intake since this study shows it doesn’t impact outcomes.
  • Rather than adding antioxidant supplements, use your fertility app to: (1) maintain a consistent sleep schedule (7-9 hours nightly), (2) track and reduce alcohol intake to moderate levels, (3) monitor weight to stay in a healthy BMI range, and (4) log stress-reduction activities like exercise or meditation. These evidence-based factors actually matter for male fertility.
  • Work with your fertility clinic to monitor sperm quality through regular testing rather than relying on supplements. Use your app to track lifestyle factors that genuinely affect fertility: exercise frequency, diet quality, stress management, and sleep. Share these data with your doctor to identify areas for improvement.

This research summary is for educational purposes only and should not replace professional medical advice. The study tested one specific antioxidant supplement formula and results may not apply to other brands or combinations. Men trying to conceive should consult with a fertility specialist or urologist before starting any supplements, as individual health conditions and medications may affect safety and effectiveness. This study does not provide medical advice for your specific situation. Always discuss supplement use with your healthcare provider, especially if you have underlying health conditions or take other medications.