Effects of N-acetyl-cysteine supplementation on sperm quality, chromatin integrity and level of oxidative stress in infertile men.

Plain-language summary

This study set out to see whether N-acetyl-cysteine (NAC, an antioxidant supplement, taken here at 600 mg a day) improves sperm quality in infertile men. Fifty infertile men with poor sperm movement and abnormal sperm shape took it for three months at a fertility research center in Qom, Iran, and were compared against their own results from before treatment. Sperm count and movement rose, while abnormal shape, DNA fragmentation (breaks in the genetic material inside sperm, where fewer breaks mean a better chance of conception) and protamine deficiency (too little of the protein that packs a sperm's DNA down tight, which leaves the DNA loosely wound and easier to damage) all fell. Markers of oxidative damage improved and testosterone rose.

Key findings

• Sperm count and motility rose after three months on 600 mg of N-acetyl-cysteine a day.
• Abnormal sperm shape and DNA fragmentation both fell.
• Protamine deficiency fell. Protamines are the proteins that pack a sperm's DNA down tight, and having too little leaves that DNA loosely wound and easier to damage, so less deficiency is the good direction.
• Total antioxidant capacity rose and malondialdehyde, a marker of oxidative damage, fell.
• There was no control group. The men were compared against themselves before treatment.