L-carnitine may boost sperm quality and fertility

Male infertility has be linked to a number of different factors.  One issue is a condition known as asthenozoospermia.  This is when sperm lacks motility (motion).

Recently (1) a study in China looked at the effect of the nutritional supplement L-carnitine on men with asthenozoospermia.   A total of 135 men with asthenozoospermia were involved in the study.   68 received 2g of L-carnitine per day as well as vitamin E for three months and 67 received vitamin E only.  All the patients underwent semen analyses before and after the treatment and the pregnancy rates of their wives were recorded. 

Results showed that men taking the L-carnitine had significantly improved sperm motility after 3 months, in addition to this the rate of pregnancy was significantly higher (at 31.1%) in the group taking L-carnitine compared to the group taking vitamin E on it’s own (3.8%).  The authors of the study conclude that “L-carnitine, capable of significantly improving sperm motility and raising the rate of pregnancy, is a safe and effective therapeutic option for asthenozoospermia(1).

This study adds to previous  research that has indicated that L-carnitine supplementation can improve sperm motility (e.g. 2,3,4)

L-carnitine is a ‘dipeptide’, a compound which consists of two amino acids (lysine and methionine), the building blocks that form proteins.  The body can produce L-carnitine on its own, so it is not essential to take it in through the diet.  It is not known exactly why L-carnitine supplementation may be useful in men suffering with asthenozoospermia and further studies will be necessary before treatment with this compound can be widely recommended for the condition.  It may be that L-carnitine may be helpful via acting as an antioxidant in the body or due to it’s role in energy metabolism.  It will be interesting to read further evidence on the subject.  If you decide you would like to try supplementation with L-carnitine it would be wise to visit your medical doctor first.

(1)Wang YX et al.  2010.  [L-carnitine: safe and effective for asthenozoospermia] [Article in Chinese].  Zhonghua Nan Ke Xue.  16(5):420-2.

(2)Balercia G et al.  2005.  Placebo-controlled double-blind randomized trial on the use of L-carnitine, L-acetylcarnitine, or combined L-carnitine and L-acetylcarnitine in men with idiopathic asthenozoospermia. Fertil Steril.  84(3):662-71.

(3)Costa M.  1994.  L-carnitine in idiopathic asthenozoospermia: a multicenter study. Italian Study Group on Carnitine and Male Infertility. Andrologia.  26(3):155-9.

(4)Cheng HJ, Chen T.  2008.  [Clinical efficacy of combined L-carnitine and acetyl-L-carnitine on idiopathic asthenospermia] [Article in Chinese] Zhonghua Nan Ke Xue.  14(2):149-51.

Written by Ani Kowal