Does L-Carnitine Improve Male Fertility?

There’s been interest in using L-carnitine and acetyl-L-carnitine to improve male fertility for some time. But do they actually help? Here’s the latest evidence.

Most clinical research shows that taking L-carnitine by mouth, with or without acetyl-L-carnitine, increases sperm count and sperm movement, and improves sperm shape and size in males with infertility from various causes. It’s not clear if taking acetyl-L-carnitine alone has the same effect. While improved sperm count and size might lead to a greater chance of pregnancy in female partners, explain to patients that clinical studies evaluating its effects on pregnancy rates are still limited and unclear. In fact, most research suggests that taking L-carnitine doesn’t improve pregnancy rates, but these studies may be too small and short in duration to properly evaluate its effectiveness.

If patients want to give L-carnitine a try, it’s likely safe for most people, with exceptions such as patients with a history of seizures. It’s usually well-tolerated – some patients might experience gastrointestinal side effects like stomach cramps and nausea. Explain that most clinical studies use doses of L-carnitine 1-3 grams by mouth daily in divided doses for up to 24 weeks, with or without acetyl-L-carnitine 1 gram daily. And always advise patients to look for products certified by a reputable third-party, such as USP or NSF.

Check out our recently updated L-carnitine and acetyl-L-carnitine monographs to learn more.