Table 1. Review of studies examining the effect of antioxidant therapy on sperm DNA fragmentation.
| Study | Supplements (daily intake) | Study design | n | Duration | SDF testing method | Result |
|---|---|---|---|---|---|---|
| Tunc et al. (16) | Vitamin C (100 mg), E (400 IU), Se (26 ìg), Zn (25 mg), folic acid (0.5 mg) and garlic (1 mg) | Prospective observational study | 50 | 3 months | TUNEL, CMA3 assay | Significant decrease in SDF [−4% (3.1–3.5%)†, P<0.01] and protamine packaging [+ 4.6% (4.4–5.8%)†, P<0.01]. No significant improvement in semen parameters |
| Ménézo et al. (17) | b-carotene (18 mg), vitamins C (400 mg), E (400 mg), Zn (500 µmol) and Se (1 µmol) | Prospective observational study | 58 | 3 months | SCSA | Significant decrease in SDF (−19.1%, P<0.01) |
| Kodama et al. (18) | Vitamins C (200 mg), E (200 mg), glutathione (400 mg) | Prospective observational study for the treatment group | 14 | 2 months | 8-hydroxy-2’-deoxyguanosine | Significant improvement in sperm concentration (+7±1 million/mL, P<0.05). Significant decrease in oxidative DNA damage (−0.4%±0.1%, P<0.05) |
| Omu et al. (19) | Group 1: Zn (400 mg); group 2: Zn (400 mg) + vitamin E (20 mg); group 3: Zn (400 mg) + vitamins E (20 mg) + C (10 mg) | Randomized placebo-controlled study | 45 (treatment—group 1: n=11; group 2: n=12; group 3: n=14); 8 placebo group | 3 months | SCSA | Improvement in SDF measures with treatment*. Significant improvement in sperm motility with the treatment group (group 1: +25%±12%; group 2: +24%±6%; group 3: +25%±9%, P<0.01) |
| Greco et al. (20) | Vitamin C (1,000 mg) + vitamin E (1,000 mg) | Prospective observational study | 29 (patients with high SDF and prior failed ICSI) | 2 months | TUNEL | Significant decrease SDF levels (−15.8%±3.6%, P<0.001). Insignificant effect on semen parameters. Significant improvement in ICSI clinical pregnancy (48.2% versus 6.9%, P<0.05) and implantation (19.6% versus 2.2%, P<0.01) rates compared with the pretreatment ICSI outcomes |
| Greco et al. (21) | Vitamin C (1,000 mg) + vitamin E (1,000 mg) | Randomized placebo-controlled study | 64 men with unexplained infertility and high SDF levels | 2 months | TUNEL | Significant decrease in SDF levels (−13%±0.5%, P<0.01). Insignificant effect on semen parameters |
| Martínez-Soto et al. (22) | Docosahexaenoic acid (DHA) (1,500 mg) | Randomized, double blind, placebo-controlled, parallel-group study | 57 (32 treatment group and 25 placebo group) | 10 weeks | TUNEL | Significant decrease in SDF levels (−17.2%±2.8%, P<0.001) in treatment group vs. (+11.2%±1.9%, P>0.05) in the placebo group. Insignificant effect on semen parameters |
| Fraga et al. (23) | Vitamin C (250 mg) | Prospective observational study | 10 | 15 weeks | 8-hydroxy-2'-deoxyguanosine | Vitamin C depletion/repletion was associated with inverse relationship with seminal vitamin C levels and oxo8dG measures (P<0.01) |
| Abad et al. (24) | L-carnitine (1,500 mg); vitamin C (60 mg); coenzyme Q10 (20 mg); vitamin E (10 mg); zinc (10 mg); vitamin (200 ìg) B9 selenium (50 ìg); vitamin B12 (1 ìg) | Prospective observational study | 20 infertile patients diagnosed with asthenoteratozoospermia | 3 months | SCD measurement done following various periods of sperm storage (0, 2, 6, 8 and 24 h) at 37 °C | Significant decrease in SDF levels (at 0 h: −8.4%±6.7%, P<0.01; at 2 h: −8.07%±5.03%, P<0.01; at 6 h: −8.58%±0.81%, P<0.01; at 8 h: −9.03%±2.79%, P<0.01; at 24 h: −20.95%±8.59%, P<0.01). Significant improvement in DDS (−1.6%±0.9%, P=0.04). Significant improvement in sperm concentration (+0.1±6.47 million/mL, P=0.04), motility (+6.5%±2.8%, P=0.02) and morphology (+1.5%±2.4%, P=0.04) |
| Vani et al. (25) | Vitamin C (1,000 mg) 5 consecutive days in a week | Prospective comparative study | 240 (120 men exposed to lead, and 120 healthy human subjects) | 3 months | Comet | Significant decrease in alkaline-labile sites and mean tail length of the comet when compared to the control group (P<0.01). Significant improvement in all semen parameters (P<0.01) |
| Gual-Frau et al. (26) | L-carnitine (1,500 mg); vitamin C (60 mg); coenzyme Q10 (20 mg); vitamin E (10 mg); zinc (10 mg); vitamin B9 (200 ìg), selenium (50 ìg), vitamin B12 (1 ìg) | Prospective observational study | 20 infertile men with grade 1 varicocele | 3 months | SCD | Significant decrease in SDF levels (−22.1%, P=0.02). 31.3% fewer highly degraded sperm cells (P=0.07), significant increase in sperm concentration (P=0.04) |
| Piomboni et al. (27) | Beta-glucan (20 mg), fermented papaya (50 mg), lactoferrin (97 mg), vitamin C (30 mg), and vitamin E (5 mg) | Prospective observational study | 36 men with leukocytospermia; 15 controls | 3 months | Acridine orange (AO) staining | No significant decrease in SDF. Significant increase in sperm morphology (+12.8%±1.3%, P<0.01) and total progressive motility (+15.8%±1.1%, P<0.01). Significant reduction in leukocyte number (−1.3±0.7 million/mL, P<0.05) |
†, interquartile range; *, no values were provided. SDF, sperm DNA fragmentation; TUNEL, terminal deoxynucleotidyl transferase dUTP nick end labeling; CMA3, chromomycin A3; SCSA, sperm chromatin structure assay; DDS, DNA degraded sperm.