The Effect of L-Carnitine on Improving Sperm Quality in Infertile Men
One of the major issues in medical science is infertility and reduced fertility. This article explores the effect of L-carnitine in improving sperm quality in infertile men.
Definition of Infertility Infertility refers to the inability to achieve pregnancy after one year of regular unprotected intercourse.
Overview of the Infertile Population Infertility is observed in 10% to 15% of people and constitutes a significant aspect of clinical medicine for many doctors. In 40% of infertility cases, male infertility is a key factor, and since sperm production disorders are the leading cause of male infertility, correcting these disorders is critical to helping couples achieve pregnancy.
Male Fertility Evaluation The chosen method for evaluating male fertility is sperm analysis, which should be conducted using at least two samples with a minimum gap of four weeks. Unfortunately, the cause of infertility in most men remains unknown, which is simply a reflection of the very limited understanding of the mechanisms governing testicular function and spermatozoa production. Other methods like IVF, ZIFT, and ICSI have allowed for fertilization and addressed many infertility problems, but the cost of these treatments is high.
Drug Treatments for Infertility Drug treatments are more affordable and available to a broader range of couples. Some oral treatments improve sperm count and motility. Drugs like L-carnitine, arginine, zinc, and various antioxidants such as selenium, Vitamin B12, Coenzyme Q10, glutathione, Vitamin E, and Vitamin C are known to be effective in improving sperm quality. L-carnitine is a derivative of the amino acids lysine and methionine and is found in meat and dairy products. It was first isolated from beef in 1905.
How Free L-Carnitine Works Free L-carnitine is essential for the beta-oxidation of long-chain fatty acids in mitochondria. Fatty acids must first be activated (attached to coenzyme A) before entering mitochondria. Once inside the mitochondria, beta-oxidation and adenosine triphosphate (ATP) production begin. L-carnitine also helps protect DNA and cell membranes from damage caused by free oxygen radicals. The highest concentration of carnitine in the human body is found in the epididymis, where its concentration is 2000 times higher than in blood. Several studies have shown a reduction in carnitine levels in the semen of infertile men.
Study Methodology Variables: In this study, variables were recorded in a form completed for each participant, including age, duration of infertility, semen volume, sperm concentration (count per milliliter), total motility (percentage of motile sperm), forward motility, percentage of sperm with normal morphology, and side effects such as nausea, vomiting, abdominal discomfort, and diarrhea.
Study Entry Criteria Based on WHO criteria, an abnormal spermogram was defined as follows in at least two samples taken four weeks apart:
- Sperm count less than 20 million per milliliter
- Total sperm motility less than 50%
- Forward sperm motility less than 25%
- Normal sperm morphology less than 30%
- Normal levels of gonadotropins, testosterone, and prolactin
Study Exclusion Criteria
- Underlying conditions like varicocele grades 3 and 4, testicular atrophy, ejaculation disorders
- Any medication use in the past two months
- Patients with azoospermia, endocrine or anatomical disorders, or infections
- Patients eligible for ICSI due to severe spermogram disorders and other infertility factors
Sample Size The sample size was set at 30 participants based on previous studies.
Placebo Characteristics The placebo was identical to the carnitine in terms of color, smell, taste, and appearance. Carnitine itself has no significant side effects, but previous studies have noted the possibility of side effects like nausea, vomiting, abdominal discomfort, and diarrhea. Patients were fully informed about these potential side effects.
Patient Grouping and Treatment Procedure Patients were randomly divided into two groups, A and B. Grouping and drug or placebo administration were done by one of the nurses, and other team members were unaware. Group A received L-carnitine tablets at a daily dose of 2 grams, while group B received the placebo. Treatment continued for two months, followed by a two-month break. After the break, the treatment was switched, and the groups continued for another two months. For each patient, a spermogram sample was taken before entering the study and at the end of every two-month period, making a total of four spermogram samples.
Male Reproductive Function Over the past decade, there has been significant progress in understanding male reproductive function and the importance of male factors in infertility.
Treatable Disorders by Medication Many infertile men have treatable disorders that can be addressed with proper diagnosis and drug treatment, leading to natural fertilization. The current study found that carnitine had a positive effect on improving abnormal sperm analysis parameters, especially in sperm motility and forward motility.
Study Results (2003 Cross-over Method) A similar study in 2003 used a cross-over method and involved 86 patients with spermogram disorders. This study found that carnitine had a positive effect on sperm count and motility, especially in patients with more severe disorders. The study concluded that in cases with more severe spermatozoa production disorders and mitochondrial metabolism defects, increasing intracellular carnitine levels is beneficial. However, no significant change was observed in sperm morphology.
Study Findings The study showed that L-carnitine treatment did not cause a significant increase in carnitine levels in semen, as carnitine acts intracellularly, and its concentration is already high in the epididymis. A minor increase in carnitine in the semen might not be statistically significant, but biologically it could have a significant impact.
Comparison Between Two Groups Comparison of the two groups showed that those receiving the drug (who initially received placebo) experienced an increase in sperm count and motility, which was statistically significant.
Conclusion of Current Study The current study showed that the most noticeable effect of carnitine was on sperm motility, likely due to its known mechanisms in energy production and antioxidant activity. This effect was particularly clear during the drug withdrawal period, where a decrease in motility was evident. In the group that initially received carnitine, a decrease in sperm count and motility was observed during the placebo period.
Spermatogenesis Cycle Since the spermatogenesis cycle lasts 74 days, a two-month break was sufficient to clear the effects of the drug and placebo and allow for re-evaluation of the spermogram. The mechanism of carnitine’s effect is not fully understood, but it might relate to its impact on epididymal conditions, reducing gamete phagocytosis and increasing sperm count. Further studies are needed to explore its role in the spermatogenesis process.
Conclusion L-carnitine has a beneficial effect in increasing sperm count and motility, especially forward motility, in patients with unexplained spermogram abnormalities. However, further studies with a larger sample size and varying motility levels are needed.
References: Amiri I, Mahmodi R, Babalhavaeji H, Sheikh N, Najafi R. Effects of Carnitine on Sperm Parameters of Infertile Males with Idiopathic Asthenospermia. Armaghan J 2008; 12(4):65-7