Treating Male Infertility With L-carnitine & Antioxidants


There has been a lot of research focusing on L-carnitine and its influence on fertility. In particular, men suffering from sub-fertility issues have been shown to improve sperm health by taking L-carnitine supplements.

carnitine increases male fertility A study by Lenzi and colleagues in 2003 confirmed that 2g of L-carnitine each day could bolster sperm concentration and motility1.

The double-blind crossover, placebo-controlled trial involved 100 men between 20 and 40 years of age. For the first two months men were either given a placebo or 2g of L-carnitine each day. This was followed with a two month washout period before the groups swapped treatments.

Results confirmed that daily consumption of 2g of L-carnitine over two months could enhance sperm motility.

Other earlier studies have also found similar results. Vitali and colleagues administered 3g of L-carnitine for three months to men with sub-fertility problems. Sperm motility and count improve in 79% of patients2.

In another study by Costa and associates, the same amount of L-carnitine taken daily was shown to enhance sperm motility by 40% and sperm count by 15%3.

Although sperm quality seems to improve with regular L-carnitine supplementation, there is an exception.

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Research by Garolla and colleagues confirmed than in order for L-carnitine to be effective, phospholipid hydroperoxide glutathione peroxidase levels must be normal4. This is an important enzyme that minimizes oxidative stress, a process which can damage sperm function.

Since antioxidants are the key to reducing oxidative stress, many physicians recommend eating antioxidant-rich food to help improve fertility. One of the most effective antioxidants is vitamin E. In 2010, Wang and associates published their findings on the effects of combining vitamin E supplementation with L-carnitine supplementation5.


Over the three month study period 135 infertile males were split into two groups. Half received vitamin E and 2g L-carnitine daily, while the rest only took vitamin E. Men taking the combination treatment recorded a 59% increase in sperm motility, although morphology and density remained the same. Subsequent conception rates increased for the men who had taken the combination of both L-carnitine and vitamin E.

Men suffering from fertility problems may find that by regularly taking L-carnitine and vitamin E that their fertility improves. For the best results, supplementation should be continuous for at least three months before any noticeable changes in sperm quality are observed.


Related studies:


  1. “Lenzi et al., 2003. Use of carnitine therapy in selected cases of male factor infertility: a double-blind crossover trial. Fertil Steril. 2003 Feb;79 (2):292-300.”
  2. “Vitali et al., Carnitine supplementation in human idiopathic asthenospermia: clinical results. Drugs Exp Clin Res. 1995;21(4):157-9.”
  3. Costa et al., L-carnitine in idiopathic asthenozoospermia: a multicenter study. Italian Study Group on Carnitine and Male Infertility. Andrologia. 1994 May-Jun;26(3):155-9.”
  4. “Garolla et al., Oral carnitine supplementation increases sperm motility in asthenozoospermic men with normal sperm phospholipid hydroperoxide glutathione peroxidase levels. Fertil Steril. 2005 Feb;83(2):355-61.”
  5. “Wang et al., L-carnitine: safe and effective for asthenozoospermia. Zhonghua Nan Ke Xue. 2010 May;16(5):420-2.”