CoQ10 has been studied in women going through IVF and in men with low sperm counts or motility, and some small trials reported better egg-retrieval numbers or semen measures. Reviews rate this evidence as low or very low certainty, and CoQ10 has not been shown to raise live-birth rates. Folic acid before conception is the one nutrient with an established public-health recommendation, and its purpose is a healthy pregnancy rather than conception itself.
Key Takeaways
- CoQ10 is a compound your cells use to make energy, and egg and sperm cells use a lot of energy. That is why researchers have studied it for egg and sperm quality.
- A 2020 meta-analysis of five small trials in women having IVF found higher clinical pregnancy rates with CoQ10 but no difference in live births.
- Cochrane reviews of antioxidants for both men and women rate the evidence as low to very low certainty and call it inconclusive.
- The CoQ10 trials described here used 300 to 600 mg a day for about two to six months. These are research amounts, not personal recommendations.
- US guidelines advise a daily supplement with 400 to 800 mcg of folic acid for anyone planning or able to become pregnant.
- Talk to your fertility specialist before adding any supplement, and tell them about every product you take.
Evidence grade: Emerging. A handful of small, short randomized trials and meta-analyses report changes in lab measures such as egg counts and semen quality, but systematic reviews rate the certainty as low to very low and find no clear effect on live births.
What CoQ10 Is and Why It Is Studied for Fertility
Coenzyme Q10 (CoQ10) is a substance made by the human body. The highest levels are in the heart, liver, kidneys and pancreas, and it is also sold as a dietary supplement. If you want to know how much comes from food, see our guide to CoQ10 foods.
CoQ10 has two roles that interest fertility researchers. It is part of the inner membrane of mitochondria, the energy factories inside cells, where it helps produce ATP, the molecule cells use for energy. It also acts as an antioxidant. Eggs and sperm need a lot of energy, and both can be damaged by oxidative stress, which is an imbalance between unstable molecules called free radicals and the body's antioxidant defenses. The Cochrane review of antioxidants for men notes that oxidative stress is thought to play a part in many cases of low sperm quality. Whether that translates into more babies is the open question.
The National Center for Complementary and Integrative Health (NCCIH) puts it plainly. CoQ10 has been studied for male fertility, but the research is too limited for any conclusions to be drawn.
CoQ10 and Egg Quality: The Research in Women
Most studies in women were done during IVF, so the results may not apply to couples trying to conceive on their own.
The 2018 trial in younger women with low ovarian reserve
In a randomized trial in China, 186 women under 35 with low ovarian reserve were assigned to take CoQ10 (200 mg three times a day, 600 mg in total) for 60 days before an IVF-ICSI cycle, or to take nothing extra. Of the 169 women analyzed, those in the CoQ10 group needed lower doses of stimulation medicine, had more eggs retrieved, had a higher fertilization rate and had more high-quality embryos. Fewer of them had an embryo transfer cancelled because embryos did not develop well.
The limits are important. The trial was open label, so the women and their doctors knew who was taking CoQ10, and there was no placebo. Clinical pregnancy and live-birth rates tended to be higher in the CoQ10 group, but the differences were not statistically significant.
The 2020 meta-analysis
A 2020 systematic review pooled five randomized trials with 449 women having assisted reproduction. Clinical pregnancy rates were 28.8% with CoQ10 and 14.1% with placebo or no treatment. However, the review found no difference in live-birth rates or miscarriage rates.
The Cochrane review of antioxidants for women
The 2020 Cochrane review of oral antioxidants for women with fertility challenges included 63 trials and 7,760 women. It covered many supplements, including CoQ10. Because the evidence was of very low quality, the authors said they were uncertain whether antioxidants improve live-birth rates. They concluded there is limited evidence to support oral antioxidants for these women. In 2026 Cochrane added an editorial note: seven of the included studies have since been retracted and two more carry expressions of concern. The editors judged that removing them would not change the review's conclusions.
CoQ10 and Sperm Quality: The Research in Men
The 2009 trial with 212 men
The trial most often quoted on CoQ10 and sperm was published in the Journal of Urology in 2009. In it, 212 men with low sperm count, motility and normal shape took 300 mg of CoQ10 a day or a placebo for 26 weeks. The CoQ10 group showed significant improvements in sperm density and motility. The change in normal sperm shape did not reach statistical significance. The study did not measure pregnancy rates, and the author said further studies were needed. In 2023 the journal published an expression of concern about this paper, which is a formal warning to readers about the reliability of a study. Treat its numbers with caution.
The Cochrane review of antioxidants for men
The 2022 Cochrane review included 90 trials with 10,303 men attending fertility clinics, testing 20 different antioxidants. Antioxidants may increase clinical pregnancy and live-birth rates, but the certainty of the evidence was low to very low. When trials at high risk of bias were removed, there was no evidence of more live births. Antioxidants also caused slightly more mild stomach discomfort than placebo. The authors concluded that, overall, the evidence is inconclusive and that larger, better-designed trials are needed.
The MOXI trial
A well-designed US trial called MOXI, published in 2020, gave 174 men with low semen quality either a daily antioxidant combination (vitamins C and E, selenium, L-carnitine, zinc, folic acid and lycopene) or a placebo. It did not include CoQ10. After three months, the antioxidants did not improve sperm shape, motility or DNA damage. Live births at six months were 15% in the antioxidant group and 24% in the placebo group, a difference that was not statistically significant.
Folic Acid Before Conception
Folic acid is the synthetic form of folate, a B vitamin. It has the clearest guidance of any nutrient in this article, but the goal is a healthy pregnancy, not a higher chance of conceiving. The US Preventive Services Task Force recommends that everyone who is planning to or could become pregnant take a daily supplement containing 400 to 800 mcg of folic acid. This lowers the risk of neural tube defects, birth defects of the brain and spine that form 21 to 28 days after conception, often before a person knows they are pregnant. The NIH Office of Dietary Supplements gives the same advice: women who could become pregnant should get 400 mcg of folic acid a day from supplements, fortified foods or both, on top of the folate in food. For more on nutrition once pregnancy begins, see our guide to key nutrients for fetal development.
For men, the evidence points the other way. The 2020 FAZST trial gave 2,370 men in couples planning fertility treatment either 5 mg of folic acid with 30 mg of zinc, or a placebo, every day for six months. Live-birth rates were almost identical (34% versus 35%), and most semen measures did not change. Sperm DNA fragmentation was slightly higher in the supplement group, and stomach upset, nausea and vomiting were more common. Note that 5 mg is five times the adult upper limit of 1,000 mcg of folic acid a day set for supplements and fortified foods.
Doses Used in Fertility Studies
| Study | Who took part | What they took | Main finding |
|---|---|---|---|
| Xu et al., 2018 | 169 women under 35 with low ovarian reserve, before IVF-ICSI | CoQ10, 600 mg a day for 60 days (open label, no placebo) | More eggs and high-quality embryos; no significant difference in pregnancy or live birth |
| Florou et al., 2020 (meta-analysis) | 449 women in 5 trials of assisted reproduction | Oral CoQ10 versus placebo or no treatment | Higher clinical pregnancy rate; no difference in live birth or miscarriage |
| Safarinejad, 2009 | 212 men with low semen quality | CoQ10, 300 mg a day for 26 weeks | Better sperm density and motility; pregnancy not measured; expression of concern issued in 2023 |
| MOXI, 2020 | 174 men with low semen quality | Antioxidant combination without CoQ10, 3 to 6 months | No improvement in semen measures or live birth |
| FAZST, 2020 | 2,370 men in couples planning fertility treatment | Folic acid 5 mg plus zinc 30 mg a day for 6 months | No change in live birth or most semen measures |
| USPSTF, 2023 | Anyone planning or able to become pregnant | Folic acid, 400 to 800 mcg a day | Recommended to lower the risk of neural tube defects |
No official dose of CoQ10 exists for fertility. The CoQ10 trials above used 300 to 600 mg a day for about two to six months. If you are curious about timing, our article on the best time to take CoQ10 covers taking it with food. Your fertility specialist is the right person to decide whether CoQ10 belongs in your plan and at what amount.
Safety and Interactions
- Side effects: NCCIH reports no serious side effects of CoQ10. Mild effects such as trouble sleeping or digestive upset can occur. Cochrane found antioxidants in general caused slightly more mild stomach discomfort than placebo in men.
- Blood thinners: CoQ10 may interact with the anticoagulant warfarin. Talk to your doctor or pharmacist before taking CoQ10 if you take warfarin. Our guide to medications that may interact with CoQ10 explains more.
- Insulin and cancer treatment: NCCIH notes CoQ10 may interact with insulin and may not be compatible with some types of cancer treatment. Talk to your doctor if you use either.
- Folic acid limits: The adult upper limit for folic acid from supplements and fortified foods is 1,000 mcg a day unless your clinician advises otherwise. If you take methotrexate, talk to your doctor before taking folic acid, because the two can interact.
- Fertility treatment and pregnancy: Tell your fertility team about every supplement you take. If you become pregnant, ask your clinician which supplements to continue.
Frequently Asked Questions
Does CoQ10 improve egg quality?
Some small trials in women having IVF found more eggs retrieved and more high-quality embryos with CoQ10, and a 2020 meta-analysis found higher clinical pregnancy rates. Neither showed a clear increase in live births, and Cochrane rates the overall evidence as low certainty. It is an open research question, not a proven effect.
How much CoQ10 was used in fertility studies?
The trials described in this article used 300 to 600 mg a day. The 2018 trial in younger women used 600 mg a day for 60 days before IVF, and the 2009 trial in men used 300 mg a day for 26 weeks. These are research amounts. Ask your fertility specialist what, if anything, makes sense for you.
Can CoQ10 help sperm quality?
A 2009 trial reported better sperm density and motility with 300 mg a day, but the journal later issued an expression of concern about that paper. The 2022 Cochrane review of antioxidants for men found the overall evidence inconclusive, and a careful US trial of a different antioxidant mix found no benefit.
Do antioxidant-rich foods improve egg and sperm quality?
The trials discussed here tested supplements, not foods, so they cannot tell us whether berries, nuts or leafy greens change egg or sperm quality. A varied diet with fruits, vegetables, whole grains and lean proteins is still a sound base for overall health before pregnancy.
Does folic acid help you get pregnant?
Folic acid is recommended before conception to lower the risk of neural tube defects, not to raise the chance of conceiving. In men, a large 2020 trial of high-dose folic acid with zinc found no change in live-birth rates. Anyone who could become pregnant is advised to take 400 to 800 mcg a day.
Sources
- National Center for Complementary and Integrative Health. Coenzyme Q10. NIH.
- NIH Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals.
- US Preventive Services Task Force; Barry MJ, Nicholson WK, et al. Folic Acid Supplementation to Prevent Neural Tube Defects: US Preventive Services Task Force Reaffirmation Recommendation Statement. JAMA. 2023.
- Showell MG, Mackenzie-Proctor R, Jordan V, Hart RJ. Antioxidants for female subfertility. Cochrane Database Syst Rev. 2020.
- de Ligny W, Smits RM, Mackenzie-Proctor R, et al. Antioxidants for male subfertility. Cochrane Database Syst Rev. 2022.
- Xu Y, Nisenblat V, Lu C, et al. Pretreatment with coenzyme Q10 improves ovarian response and embryo quality in low-prognosis young women with decreased ovarian reserve: a randomized controlled trial. Reprod Biol Endocrinol. 2018.
- Florou P, Anagnostis P, Theocharis P, et al. Does coenzyme Q10 supplementation improve fertility outcomes in women undergoing assisted reproductive technology procedures? A systematic review and meta-analysis of randomized-controlled trials. J Assist Reprod Genet. 2020.
- Safarinejad MR. Efficacy of coenzyme Q10 on semen parameters, sperm function and reproductive hormones in infertile men. J Urol. 2009.
- Steiner AZ, Hansen KR, Barnhart KT, et al. The effect of antioxidants on male factor infertility: the Males, Antioxidants, and Infertility (MOXI) randomized clinical trial. Fertil Steril. 2020.
- Schisterman EF, Sjaarda LA, Clemons T, et al. Effect of Folic Acid and Zinc Supplementation in Men on Semen Quality and Live Birth Among Couples Undergoing Infertility Treatment: A Randomized Clinical Trial. JAMA. 2020.
Disclosure: OPA Nutrition sells supplements, including products mentioned in this article. This content is for education only and is not medical advice. Statements about dietary supplements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your healthcare provider before using any supplement, especially if you take medication or have a medical condition.
Written and reviewed by Michael Gonzales, Founder, OPA Nutrition · Last reviewed: · How OPA researches and writes
