Struggling with fertility issues can be devastating for you and your partner, leaving you unsure of where to turn to for help. One option that is growing in popularity is turning to L-carnitine for fertility. L-carnitine is highly favorable for couples who are struggling to conceive.
Fertility studies have usually focused on the female part of fertilization, including ovulation and other factors, but male fertility issues are complex as well. Improving sperm health and motility is essential, as is regulating hormone levels and maintaining an environment that promotes healthy sperm.
Even though your body naturally makes L-carnitine, some people may not make enough of it and may not get the right amount from their diet. That’s when supplements of acetyl l-carnitine for fertility can help. But what can L-carnitine do to improve fertility in men and women?
What Is L-Carnitine?
L-carnitine is a naturally occurring amino acid derivative that plays a critical role in cellular energy production by transporting fatty acids into the mitochondria. It also acts as an antioxidant, protecting cells from oxidative damage. Found in high concentrations in the male reproductive tract, L-carnitine is available through red meat, dairy, and fish, though supplementation may be necessary for those with low levels.
L-carnitine1 is a naturally occurring amino acid derivative that, in the past, has been used for weight loss and to improve brain function. It plays an important role in energy production because it transports fatty acids2 into your cells’ mitochondria. It also helps remove toxins from your cells. This natural antioxidant exists mainly in the seminal fluid of all mammals, though it’s also present in the heart and the brain.
L-carnitine belongs to a class of nutrients called “quasi-vitamins” or “conditionally-essential” nutrients.3 It’s a supplement that can help with athletic performance, speeding up recovery and increasing oxygen supply to your muscles. It can maintain cell membrane stability while at the same time reducing oxidative stress.
L-carnitine also plays a role in brain function, helping to prevent age-related mental decline.4 It impacts heart health, too, improving cardiovascular function.5 L-carnitine helps reduce inflammation and can improve insulin sensitivity.6 Because it helps recover from intense exercise, it’s a popular choice for athletes.
L-carnitine is just one type of carnitine. You can get it from a few sources, depending on your diet. These include:
- Beef
- Cheese
- Ice cream
- Whole milk
- Codfish
- Chicken breast
For people who follow vegetarian or vegan diets, however, getting enough L-carnitine may be more complicated. That is when taking a supplement can be a good option. Even if you eat meat, your body may still not be getting enough of it if you’re not able to produce it as successfully as you should.
The production of L-carnitine7 requires an adequate consumption of the amino acids lysine and methionine, as well as vitamin C. Without these, your natural L-carnitine levels may not be enough.
What Does L-Carnitine Do for Fertility?
L-carnitine supports fertility primarily by improving sperm health, motility, and count in men, and by supporting mitochondrial function and egg quality in women. Research shows that infertile men have significantly lower L-carnitine levels, and supplementation for as little as two to three months can improve sperm parameters. Its antioxidant properties also protect both sperm and egg cells from oxidative damage.
L-carnitine is essential for the function of all of your cells, so having lower levels of it impacts your fertility. That is especially true for men. In the male body, there are high concentrations of carnitine8 in the reproductive tract, which suggests it’s essential for the maturation of sperm protozoa. It’s found in the epididymis, a segment of the spermatic ducts that store, mature, and transport spermatozoa between the testes and the vas deferens.
In a recent study,9 scientists realized that infertile men have significantly lower levels of L-carnitine. In contrast, those who have a high concentration of it in their ejaculate tend to have better testicular function. But what are the L-carnitine fertility benefits?
Improves Sperm Health
One of the most vital things L-carnitine does for male fertility is improve sperm health. L-carnitine for sperm improves health functions because it may protect sperm plasma membranes10 with high levels of unsaturated fatty acid contents. That promotes sperm maturation and enhances sperm fertilizing. It also appears to improve the production of normal-shaped sperm cells.
Abnormally shaped sperm cells11 can easily lead to fertility issues, making it more difficult for the sperm to penetrate the egg. These sperm cells can have deformed heads or even appear with two heads, while others can have multiple tails — all of which make it impossible to reach the egg and penetrate it. The higher the number of abnormal sperm cells, the lower the chances of fertilization, which is why a supplement like L-carnitine is crucial.
To further help in this goal, L-carnitine can even prevent abnormal sperm cells12 from regenerating. That allows room only for the healthiest and most normal cells. L-carnitine also helps reduce cell death as a result of apoptosis,13 which is programmed cell death to eliminate damaged or unwanted cells.
Increases Sperm Motility
L-carnitine also helps with total sperm motility, as well as progressive sperm motility, often in just three months14 after starting to take a supplement. It can do this because it helps produce energy within the sperm’s mitochondria.15 Sperm count can also increase, along with sperm quality.
Most of the spermatozoa that leave the testes are infertile,16 only becoming fertile after undergoing several biochemical processes while they cross the male and female genital tracts. Throughout this journey, motility changes occur, along with chromatin changes. L-carnitine can help as these changes occur, aiding in the creation of more fertile spermatozoa.17
A study18 shows that a treatment of two months involving both L-carnitine and L-acetyl carnitine increased sperm motility. Normal sperm motility is around 60%,19 and L-carnitine helps maintain sperm within this average, which is vital for men with asthenospermia. L-carnitine can do this by helping to increase testosterone production,20 which improves testicular function and leads to a more robust sperm count.
Sperm count is a concern these days as well. Everything from environmental pollutants to some medications can lower sperm count and make conception more difficult. As with everything else that impacts sperm health, oxidative stress is an important factor in sperm count.21
L-carnitine may also improve varicocele,22 another vital benefit that impacts overall sperm health. Varicocele is a condition where the veins in the scrotum swell, elevating testicular temperature and reducing blood flow to the area. Both of these things negatively impact sperm health. L-carnitine supplements can help sperm parameters so there are more viable sperm cells available for fertilization.
Works as an Antioxidant
Another L-carnitine sperm benefit is that it works to decrease oxidative damage.23 Oxidative damage occurs when there is an imbalance between antioxidants and free radicals, also called reactive oxygen species (ROS). Free radicals are very reactive chemicals that form naturally as part of the cellular respiration process in mitochondria. Oxidative stress damages genetic material or damages the cell’s outer wall, made of lipids, leading to cell death.
It can occur anywhere in the body, and it’s a significant problem for people who have fertility issues. Because sperm cells have mitochondria and walls containing high levels of polyunsaturated fat, they are prone to oxidative stress.
L-carnitine may improve sperm chromatin quality24 and strengthen the protamine packaging damaged from free radicals. Oxidative stress causes DNA damage to sperm, which can lead to fertility issues. It also decreases mitochondrial energy, which slows down motility.
L-carnitine also helps increase glial cell-derived neurotrophic factor25 (GDNF), a protein that prompts sperm self-renewal.
How Does L-Carnitine Benefit Male vs. Female Fertility?
For men, L-carnitine at 1,500–3,000 mg/day targets sperm motility, count, and DNA integrity through its antioxidant and mitochondrial support mechanisms. For women, 1,000–2,000 mg/day supports egg quality and mitochondrial energy production in maturing oocytes, which is particularly relevant for women over 35 experiencing age-related fertility decline. Results typically require a minimum of three months of supplementation.
L-carnitine offers benefits for both men and women who are having trouble conceiving. Because it improves egg health, sperm health, and sperm production, adding a supplement may be an option to consider. The exact supplement levels you need will depend on your overall health and any known fertility issues you have, so make sure to consult with your doctor before you start taking L-carnitine to determine the appropriate level for your situation.
| Men | Women | |
|---|---|---|
| Primary benefit | Sperm motility, count, and DNA integrity | Egg quality and mitochondrial energy in maturing eggs |
| Recommended dose | 1,500–3,000 mg/day | 1,000–2,000 mg/day |
| Best form | L-Carnitine + Acetyl-L-Carnitine combination | L-Carnitine Fumarate or L-Carnitine Tartrate |
| Key evidence | Clinical trials show improvements in sperm motility and count | Emerging evidence for egg quality support, especially over 35 |
| Time to results | Minimum 3 months (one sperm cycle) | Minimum 3 months (one egg maturation cycle) |
| Dietary sources | Red meat (highest); poultry; fish; dairy. Vegans have significantly lower baseline levels. | |
L-Carnitine for Male Fertility
L-carnitine fertility benefits for men are significant, targeting the leading causes of infertility: low sperm count, low sperm motility, DNA damage, and sperm health issues. L-carnitine enhances sperm parameters and regulates hormone levels. Perhaps its most important benefit is that it prevents oxidative stress, one of the most significant factors affecting male fertility.26 Oxidative stress impacts everything from sperm motility to the number of viable cells.
L-carnitine sperm volume can improve because it promotes the maturation of spermatozoa, making more sperm cells viable for fertilization. That is why it is a good choice for men with low sperm counts. L-carnitine also strengthens sperm, making it possible to penetrate the cervical mucosa. Most of these benefits are accomplished because of the antioxidant properties of L-carnitine.
L-Carnitine for Female Fertility
As women age, the chances of becoming pregnant decrease27 because of fluctuating hormone levels and the inability of the ovaries to release quality eggs. Mitochondrial function also decreases both in the eggs and in the ovaries. The mitochondria are in charge of generating energy in the form of adenosine triphosphate (ATP).28 Because pregnancy requires a high amount of energy, it needs a lot of ATP, which can be a concern for women approaching their 40s.
The mitochondria in cells depend on carnitine to produce ATP. L-carnitine female fertility benefits include supporting mitochondrial function29 by also getting rid of molecules that can be toxic to mitochondria while at the same time helping to stabilize mitochondrial membranes.
As with male fertility, female fertility can suffer from oxidative stress. Oxidative stress impacts egg quality and can even affect the success of IVF treatment.30 Women who take L-carnitine female fertility supplements increase their chances of having better-quality embryos, higher pregnancy rates, and improved embryo function than those who do not. L-carnitine also appears to help with the improvement of ovulation31 and the health of the endometrium.
How Do You Choose the Right L-Carnitine Supplement?
When selecting an L-carnitine supplement for fertility, consider the form (L-carnitine tartrate for general use, acetyl-L-carnitine for additional benefits), purity (avoid fillers and additives), and dose appropriate for your situation. For male fertility, a combination of L-carnitine and acetyl-L-carnitine is best supported by research. Always consult your doctor before starting supplementation.
Choosing the right L-carnitine supplement is not always straightforward because of the many options available. The type of L-carnitine you need is one of the factors you want to consider because the most common types are L-carnitine tartrate and acetyl-l-carnitine.
L-carnitine tartrate is the most popular because of its comprehensive benefits, from helping with athletic performance to enhancing weight loss and helping with fertility issues. Another factor to consider is the purity and quality of the supplement. It is imperative to make sure you avoid supplements that contain additives, fillers, or low-quality ingredients.
When deciding on the supplement, you also want to read customer reviews since this will give you a sense of what results you can expect. You want to opt for a reputable brand with products that provide overall satisfaction to its customers and that outline all of the ingredients so you know what you’re getting.
You also want to make sure to speak with your doctor about the various options you have so that they can help you make the best possible decision. Something important to remember is that when it comes to supplements, you shouldn’t base your purchasing decision solely on price since cheaper products might not provide the quality ingredients you want.
Boost Fertility with L-Carnitine With FertilitySmart
L-carnitine is a powerful supplement that can impact both male and female fertility. L-carnitine fertility female and male supplements can offer many benefits, including reducing oxidative stress affecting sperm and eggs and helping with sperm motility and health. It gives you the boost that you need to have the best chance at fertilization. What’s even better is that you also enjoy the added health benefits that taking L-carnitine can provide, including inflammation reduction and so much more.
Fertility Smart offers excellent supplements containing L-carnitine for men. Our Conceive for Men supplements contain L-carnitine with the added benefit of amino acids like L-arginine and L-taurine, as well as green tea extract. We only offer products that have been tested and contain only the highest-quality ingredients.
We know how stressful infertility issues can be, and finding the right treatment takes time and effort. With our dedication to providing only the most reliable products, you are in good hands when you turn to Fertility Smart.
We aim to offer compassionate care for every family who embarks on this process. We provide a natural, non-prescriptive approach to balance male and female hormones to facilitate reproductive wellness, fertility, and conception. Read more about our many products to find the one that suits your needs best.
Frequently Asked Questions
How long does it take for L-carnitine to improve fertility?
Most research suggests a minimum of three months of consistent supplementation is needed to see improvements in fertility parameters. This timeframe aligns with the sperm development cycle in men (approximately 74 days) and the egg maturation cycle in women. Some studies have shown improvements in sperm motility after just two months of combined L-carnitine and acetyl-L-carnitine supplementation.
What is the recommended dosage of L-carnitine for fertility?
For male fertility support, clinical studies typically use 1,500–3,000 mg per day, often as a combination of L-carnitine and acetyl-L-carnitine. For female fertility, 1,000–2,000 mg per day is generally recommended. Always consult your healthcare provider for personalised dosage guidance based on your specific situation.
Can vegans get enough L-carnitine for fertility?
Vegans tend to have significantly lower baseline L-carnitine levels because the richest dietary sources are animal products such as red meat, dairy, and fish. While the body can synthesise small amounts from the amino acids lysine and methionine (with adequate vitamin C), supplementation is often recommended for vegans who are trying to conceive.
Is L-carnitine safe to take while trying to conceive?
L-carnitine is generally considered safe at recommended dosages. Side effects are uncommon but may include mild gastrointestinal discomfort in some individuals. However, those with thyroid conditions should exercise caution, and anyone taking fertility medications should consult their doctor before starting L-carnitine supplementation to avoid potential interactions.
What is the difference between L-carnitine and acetyl-L-carnitine?
L-carnitine tartrate is the most common form and is well-studied for general fertility and energy production benefits. Acetyl-L-carnitine (ALCAR) is a form that more easily crosses the blood-brain barrier and may offer additional antioxidant protection. For male fertility, research suggests that a combination of both forms may be more effective than either alone.
Does L-carnitine help with IVF success rates?
Emerging research suggests L-carnitine supplementation may support IVF outcomes by improving egg quality through enhanced mitochondrial function, reducing oxidative stress in both sperm and eggs, and potentially improving embryo quality. Women who supplemented with L-carnitine before IVF showed higher pregnancy rates in some studies, though more research is needed to confirm these findings.
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3, 31 Agarwal, Ashok, et al. “Role of L-Carnitine in Female Infertility.” Reproductive Biology and Endocrinology : RB&E, vol. 16, Jan. 2018, p. 5. PubMed Central, https://doi.org/10.1186/s12958-018-0323-4.
4 Malaguarnera, Mariano, et al. “L-Carnitine Treatment Reduces Severity of Physical and Mental Fatigue and Increases Cognitive Functions in Centenarians: A Randomized and Controlled Clinical Trial2.” The American Journal of Clinical Nutrition, vol. 86, no. 6, Dec. 2007, pp. 1738–44. ScienceDirect, https://doi.org/10.1093/ajcn/86.5.1738.
5 Kaneko, Mai, et al. “L-Carnitine Improved the Cardiac Function via the Effect on Myocardial Fatty Acid Metabolism in a Hemodialysis Patient.” Internal Medicine, vol. 57, no. 24, Dec. 2018, pp. 3593–96. PubMed Central, https://doi.org/10.2169/internalmedicine.1055-18.
6 Ko, Jennifer, et al. “The Glycemic, Cholesterol, and Weight Effects of L-Carnitine in Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.” Diabetes Epidemiology and Management, vol. 10, Apr. 2023, p. 100122. ScienceDirect, https://doi.org/10.1016/j.deman.2022.100122.
7 “L-Carnitine - A Review of Benefits, Side Effects and Dosage.” Healthline, 27 Mar. 2023, https://www.healthline.com/nutrition/l-carnitine.
8, 14 Mongioi, L., et al. “The Role of Carnitine in Male Infertility.” Andrology, vol. 4, no. 5, Sept. 2016, pp. 800–07. DOI.org (Crossref), https://doi.org/10.1111/andr.12191.
9 Sheikh, N., et al. “L-Carnitine Level in Seminal Plasma of Fertile and Infertile Men.” Journal of Research in Health Sciences, vol. 7, no. 1, July 2007, pp. 43–48.
10, 24 Aliabadi, Elham, et al. “Effects of L-Carnitine and L-Acetyl-Carnitine on Testicular Sperm Motility and Chromatin Quality.” Iranian Journal of Reproductive Medicine, vol. 10, no. 2, Mar. 2012, pp. 77–82. PubMed Central, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4163266/.
11 “Abnormal Sperm Morphology? What It Could Mean for You.” Mayo Clinic, https://www.mayoclinic.org/diseases-conditions/male-infertility/expert-answers/sperm-morphology/faq-20057760. Accessed 15 Jan. 2024.
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13 Lee, Yuan-Chii Gladys, et al. “L-Carnitine Reduces Reactive Oxygen Species/Endoplasmic Reticulum Stress and Maintains Mitochondrial Function during Autophagy-Mediated Cell Apoptosis in Perfluorooctanesulfonate-Treated Renal Tubular Cells.” Scientific Reports, vol. 12, no. 1, Mar. 2022, p. 4673. www.nature.com, https://doi.org/10.1038/s41598-022-08771-3.
15, 25 Mateus, Filipa G., et al. “L-Carnitine and Male Fertility: Is Supplementation Beneficial?” Journal of Clinical Medicine, vol. 12, no. 18, Jan. 2023, p. 5796. www.mdpi.com, https://doi.org/10.3390/jcm12185796.
16 Gervasi, Maria Gracia, and Pablo E. Visconti. “Molecular Changes and Signaling Events Occurring in Sperm during Epididymal Maturation.” Andrology, vol. 5, no. 2, Mar. 2017, pp. 204–18. PubMed Central, https://doi.org/10.1111/andr.12320.
18 Lenzi, Andrea, et al. “A Placebo-Controlled Double-Blind Randomized Trial of the Use of Combined l-Carnitine and l-Acetyl-Carnitine Treatment in Men with Asthenozoospermia.” Fertility and Sterility, vol. 81, no. 6, June 2004, pp. 1578–84. PubMed, https://doi.org/10.1016/j.fertnstert.2003.10.034.
19 Leslie, Stephen W., et al. “Male Infertility.” StatPearls, StatPearls Publishing, 2023. PubMed, http://www.ncbi.nlm.nih.gov/books/NBK562258/.
20 Koohpeyma, Farhad, et al. “The Protective Effect of L-Carnitine on Testosterone Synthesis Pathway, and Spermatogenesis in Monosodium Glutamate-Induced Rats.” BMC Complementary Medicine and Therapies, vol. 22, Oct. 2022, p. 269. PubMed Central, https://doi.org/10.1186/s12906-022-03749-0.
21 Alahmar, Ahmed T. “Role of Oxidative Stress in Male Infertility: An Updated Review.” Journal of Human Reproductive Sciences, vol. 12, no. 1, 2019, pp. 4–18. PubMed Central, https://doi.org/10.4103/jhrs.JHRS_150_18.
22 Sofimajidpour, Heshmatollah, et al. “Comparison of the Effects of Varicocelectomy and Oral L-Carnitine on Sperm Parameters in Infertile Men with Varicocele.” Journal of Clinical and Diagnostic Research : JCDR, vol. 10, no. 4, Apr. 2016, pp. PC07-PC10. PubMed Central, .
26 Tremellen, Kelton. “Oxidative stress and male infertility—a clinical perspective.” Human Reproduction Update, vol, 14, no. 3. June 2008, pp. 243–258. Oxford, https://doi.org/10.1093/humupd/dmn004.
27 Female Age-Related Fertility Decline. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2014/03/female-age-related-fertility-decline. Accessed 15 Jan. 2024.
28 Dunn, Jacob, and Michael H. Grider. “Physiology, Adenosine Triphosphate.” StatPearls, StatPearls Publishing, 2023. PubMed, http://www.ncbi.nlm.nih.gov/books/NBK553175/.
30 Al-Saleh, Iman, et al. “Oxidative Stress and DNA Damage Status in Couples Undergoing in Vitro Fertilization Treatment.” Reproduction and Fertility, vol. 2, no. 2, May 2021, pp. 117–39. raf.bioscientifica.com, https://doi.org/10.1530/RAF-20-0062.
Marina Carter
Fertility Health Writer at FertilitySmart
Marina Carter is a specialist health writer with nearly a decade of experience in reproductive health, fertility nutrition, and evidence-based conception support. She has authored over 30 in-depth articles for FertilitySmart, translating peer-reviewed research into clear, practical guidance for individuals and couples on their fertility journey. Read full bio →