The finding could help men coping with fertility issues -- specifically, those men whose sperm don't move very well.
Revving Up Sperm Movement
For a sperm to fertilize an egg, the sperm must be mobile and swim to the woman's egg. But sperm that don't move very well aren't as likely to succeed. Their chances of reaching the egg to start a pregnancy are diminished.
Carnitine supplements might help spur those sperm into motion, say the researchers, who included the University of Padova's Andrea Garolla, PhD.
Carnitine is available over the counter. But, like all supplements, it's not regulated by the government, and patients should tell their doctors if they are taking it.
The study was small; only 30 men participated. Their average age was 34. All had sought help for fertility problems. The men were diagnosed with decreased sperm motility.
For three months, the men took a placebo. Then they took 2 grams of L-carnitine supplements orally every day for three months. After that, the men didn't take anything for another three months.
Semen samples were taken four times: at the study's start, after taking the placebo for three months, after taking carnitine for three months, and three months after treatment ended.
Sperm motility improved while the men took the carnitine supplements. The placebo didn't help at all.
The benefit's extent varied depending on the men's condition. The key may lie in their mitochondria, the main power source for cells.
Some participants' sperm had mitochondria that weren't working properly. Their sperm motility improved with carnitine, but their results didn't match those with normal mitochondria.
The improvement was temporary. Three months after treatment ended, sperm motility was still a bit better than before the study, but not by much. The men whose sperm motility improved the most with the carnitine supplements had the sharpest drop in sperm motility after the treatment ended.
The study appeared in the February issue of Fertility and Sterility.
Meat, poultry, fish, and dairy products are the richest sources of L-carnitine. Tempeh, wheat, and avocados contain some L-carnitine, while fruits, vegetables, and grains contain little. It is primarily made in the liver and kidneys and plays an important role in energy production by mitochondria.