Are Male Fertility Supplements Helpful?

If you’re struggling with male infertility, you may have read or heard from friends and acquaintances that fertility supplements can help improve sperm count and boost male fertility. If you’re wondering whether it’s just a hype, this post will help you understand what science says about these supplements.

What Do Most Male Fertility Supplements Contain?

The composition of fertility supplements varies from one manufacturer to another. This post will describe the most common ingredients that these supplements contain.

D-aspartic acid (D-AA): This amino acid regulates testosterone synthesis. It acts on the brain to cause the release of reproductive hormones (such as luteinizing hormone and follicle stimulating hormone) and growth hormone.

Antioxidants: These protect DNA, the hereditary material in humans and almost all other organisms, and cell membranes from destruction by free radicals. Some examples of antioxidants include L-carnitine/acetylcarnitine, vitamin C (also known as ascorbic acid), vitamin E, selenium, and coenzyme Q10 (CoQ10).

Vitamins: These include vitamin 12 (methylcobalamin), folic acid (one of the B vitamins), and vitamin D. These vitamins can be found in many foods and are also helpful supplements in pregnant women.


Minerals: Like vitamins, minerals are also needed for the proper functioning of the body. Some minerals that you’ll find in male fertility supplements include zinc and manganese.  

How Do These Supplements Affect Male Fertility?

D-aspartic acid (D-AA)

This amino acid is not only found in the nervous and endocrine system but also in human seminal plasma and spermatozoa. Men with oligoasthenoteratospermia were shown to have significantly lower levels of D-AA in their seminal plasma and spermatozoa than those with normal sperm count and motility (the level of D-AA was 3.1-fold lower in seminal plasma and 2.16-fold lower in spermatozoa).

Key Takeaway: While laboratory studies suggest a relationship between poor sperm count and motility, further studies should be conducted to determine whether supplementation with D-AA can effectively improve sperm quality and motility.


Carnitines are found in the highest concentrations in the epididymis and spermatozoa. The spermatozoa use energy provided by carnitine and acetylcarnitine during sperm metabolism, thereby positively impacting the process of spermatozoa production. Carnitines protect the sperm and prevent cell membrane destruction due to oxidative stress. In fact, there is evidence that sperm quality and function is enhanced when a man takes carnitine and acetylcarnitine regularly.

Other researchers have found a relationship between low carnitine levels and sperm disorders such as azoospermia (condition where a man’s semen contains no sperm) and asthenospermia (condition characterized by reduced sperm motility). Other evidence suggests that acetylcarnitine may be one of the most beneficial supplements for male infertility.

Some researchers analyzed the data from nine studies on acetylcarnitine and male infertility and concluded that pregnancy rates were improved in infertile men who regularly took this amino acid. Additionally, supplementation with L-carnitine was associated with improved sperm quality and motility and decreased sperm abnormality.

A randomized controlled trial showed that infertile men with oligoasthenoteratozoospermia who received 2 g/day L-carnitine and 1 g/day L-acetyl carnitine (LAC) for six months had improved sperm motility compared with those who received a placebo. 

Key Takeaway: L-carnitine is very effective because it helps sperm cells get the energy needed to help them function properly.

Vitamin C

Conditions such as disease, old age, poor lifestyle habits, or exposition to environmental toxins cause the levels of reactive oxygen species in our bodies to reach deleterious levels.

While reactive oxygen species are normally produced in the bodies of healthy people, their levels are controlled such that they never reach levels considered harmful to the body.

People with high reactive oxygen species levels are at risk of developing chronic diseases. Additionally, it has been reported that very high levels of reactive oxygen species can cause infertility in men.

It is thought that the intake of vitamin C may help counteract some of the damage caused by oxidative reactive species. Additionally, evidence points toward the improvement of semen quality with vitamin C supplementation.

An interventional study reported that infertile men who took oral vitamin C 1,000 mg twice daily for two months had increased sperm motility and sperm count.

The authors observed a 92% increase in sperm motility and > 100% increase in sperm count in the participants. The proportion of deformed sperm cells also decreased by 55% on average.

Similar findings were reported in a study that included 120 healthy men and 120 men who received prophylactic vitamin C at a dose of 1000 mg/day for five consecutive days in a week for three months. 

Key Takeaway: Vitamin C may help improve fertility in infertile men with high levels of reactive oxygen species. However, more research is needed to draw definitive conclusions on the relationship between vitamin C supplementation and male fertility.

Vitamin D

Vitamin D has several important functions. Perhaps the most vital are regulating the absorption of calcium and phosphorus and facilitating normal immune system function.

Besides being essential for bone and teeth growth and development as well as improving our resistance to fight certain diseases, vitamin D may also boost testosterone levels.

One study reported an association between vitamin D levels and testosterone levels in men. In a randomized controlled study conducted on overweight men with vitamin D deficiency, it was reported that supplementation with oral vitamin D 83 μ g daily for one year resulted in a significant increase in testosterone levels.

Key Takeaway: Vitamin D supplementation may increase testosterone levels in men. However, more research should be conducted to confirm this finding.

Zinc and Folate

You probably already know that folate is an essential vitamin that should be taken by women during the preconception period and pregnancy. 

According to a study that included 108 fertile and 103 subfertile men, the administration of oral zinc sulfate 66 mg and oral folic acid 5 mg daily for six months resulted in a 74% improvement in sperm count among men with fertility problems.

Researchers did not find a significant benefit to taking either zinc or folic acid individually—sperm count was only improved when these two were combined.

Key Takeaway: Zinc and folate when taken together can help in the process of spermatogenesis.

Other Antioxidants

Cochrane review on antioxidant intake in male partners of couples (2876 couples in 34 studies) reported significantly higher pregnancy rates and increased live delivery rates among men who received oral antioxidants.

It is thought that excessive reactive oxidative species leading to situations of oxidative can negatively impact the outcome of assisted reproduction. This subsequently leads to decreased fertilization, implantation, and pregnancy rates.

The administration of antioxidants may decrease oxidative stress, which can cause sperm count reduction, asthenospermia (reduced sperm motility), and DNA damage.

Key Takeaway: Oral antioxidant therapy in male partners of couples undergoing assisted reproductive therapy may help improve pregnancy outcomes. However, further well-designed studies are required to determine relevant antioxidants (either singly or in combination) and optimal dosages for men with fertility issues.


Overall, the current evidence suggest that these supplements may improve fertility in men. However, you should be aware that there isn’t always a cure for infertility and simple changes in your lifestyle and diet can improve your fertility.

These changes include decreasing your exposure to chemicals, eating healthy food, exercising regularly, and avoiding tobacco, excessive alcohol consumption, refined foods and those with artificial additives.

Further Reading

Agarwal A, Said TM. Carnitines and male infertility. Reprod Biomed Online. 2004 Apr;8(4):376-84.

Agarwal A, Virk G, Ong C, du Plessis SS. Effect of oxidative stress on male reproduction. World J Mens Health. 2014 Apr;32(1):1-17. Read the article.

Agarwal A, Durairajanayagam D, du Plessis SS. Utility of antioxidants during assisted reproductive techniques: an evidence based review. Reprod Biol Endocrinol. 2014 Nov 24;12:112. Read the article.

Akmal M, Qadri JQ, Al-Waili NS, Thangal S, Haq A, Saloom KY. Improvement in human semen quality after oral supplementation of vitamin C. J Med Food. 2006 Fall;9(3):440-2. Read the article.

D’Aniello G, Ronsini S, Guida F, Spinelli P, D’Aniello A. Occurrence of D-aspartic acid in human seminal plasma and spermatozoa: possible role in reproduction. Fertil Steril. 2005 Nov;84(5):1444-9. Read the article.

Lenzi A, Sgrò P, Salacone P, Paoli D, Gilio B, Lombardo F, Santulli M, Agarwal A, Gandini L. A placebo-controlled double-blind randomized trial of the use of combined l-carnitine and l-acetyl-carnitine treatment in men with asthenozoospermia. Fertil Steril. 2004 Jun;81(6):1578-84. Read the article.

Showell MG, Brown J, Yazdani A, Stankiewicz MT, Hart RJ. Antioxidants for male subfertility. Cochrane Database Syst Rev. 2011 Jan 19;(1):CD007411. Read the article.

Vani K, Kurakula M, Syed R, Alharbi K. Clinical relevance of vitamin C among lead-exposed infertile men. Genet Test Mol Biomarkers. 2012 Sep;16(9):1001-6. Read the article.

Wong WY, Merkus HM, Thomas CM, Menkveld R, Zielhuis GA, Steegers-Theunissen RP. Effects of folic acid and zinc sulfate on male factor subfertility: a double-blind, randomized, placebo-controlled trial. Fertil Steril. 2002 Mar;77(3):491-8. Read the article.

Zhou X, Liu F, Zhai S. Effect of L-carnitine and/or L-acetyl-carnitine in nutrition treatment for male infertility: a systematic review. Asia Pac J Clin Nutr. 2007;16 Suppl 1:383-90. Read the article.


Nick is a research-oriented fanatic, family man, and outdoors enthusiast who loves cars, boats, and fishing. He has a full-time job at a research facility in Cape Town, South Africa, and writes part-time because he feels the need to share his knowledge in terms that are accessible to the general public. Follow Nick on Quora: Protection Status