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A Dutch study involving more than 1100 men found that the antioxidant supplement Impryl did not improve fertility. The trial, led by Wiep de Ligny, MD, from the Department of Obstetrics and Gynecology, Radboud University Medical Center, Nijmegen, the Netherlands, and published in JAMA Network Open, reported no difference in pregnancy rates among partners of men who received Impryl compared with those who a received placebo.

Impryl, an over-the-counter antioxidant supplement manufactured by Parthenogen Europe, is marketed to men and women trying to conceive and has gained significant visibility through social media promotion. It contains betaine, cystine, zinc, and several B vitamins and is sold in pharmacies and online. Despite its popularity, the effectiveness of this supplement in improving fertility has not been demonstrated in clinical trials.

Study Design

A multicenter, randomized, placebo-controlled, double-blind trial was conducted between May 2018 and February 2024. A total of 1171 men (median age, 31-38 years) and their partners (median age, 30-35 years) were included in the study. Of these, 591 men received antioxidant supplements, and 580 received a placebo. Follow-up continued until December 2024.

All couples received fertility care, including expectant management, intrauterine insemination, in vitro fertilization (IVF), and intracytoplasmic sperm injection (ICSI). Couples were excluded if the woman underwent ovulation induction or IVF solely due to bilateral tubal disease.

The primary outcome was an ongoing pregnancy conceived within 6 months after randomization. Secondary outcomes included semen parameters, sperm DNA fragmentation, fertilization and embryo utilization rates following IVF or ICSI, biochemical and clinical pregnancy rates, first-trimester pregnancy loss, ectopic pregnancy rate, cumulative number of pregnancies, time to pregnancy, and adverse events.

Key Results

The men received either a placebo or one Impryl tablet daily for 6 months. Each Impryl tablet contained 200 mg betaine, 200 mg L-cystine, 16 mg vitamin B3, 10 mg zinc, 1.4 mg vitamin B6, 1.4 mg vitamin B2, 400 µg folic acid (vitamin B9), and 2.5 µg vitamin B12. The results were analyzed using the intention-to-treat principle.

At 6 months, the ongoing pregnancy rate was 33.8% in the Impryl group, with 193 of the 571 women conceiving successfully. In the placebo group, the rate was 37.5%, with 208 of the 555 women conceiving. Researchers found that the difference was statistically insignificant.

During the optimal treatment window of 4-6 months, accounting for the 72-day spermatogenesis cycle, the ongoing pregnancy rates were 15.5% and 21.5% in the Impryl and placebo groups, respectively. No significant intergroup differences were observed for the secondary endpoints.

Clinical Implications

Based on these results, the investigators did not support the use of Impryl in men seeking fertility treatment. Goodlife Pharma, the former distributor, stopped selling the supplement and now directs customers to other sources, stating that the company is focusing on prescription medications for fertility treatment.

This story was translated from Medscape’s German edition.