Fertility supplements for men: What they are, how they work, and why to take them

As sperm counts around the world plummet for as of yet unknown reasons and research indicates that male fertility issues account for 40-50% of infertility cases, many men who are struggling to conceive may wonder if they can do something to improve their chances. And, of course, the world of supplements stands at the ready, offering blends specifically advertised to boost male fertility. But do these products work?

Are there any supplements that you can take to boost your fertility?

There are some widely available nutrients have been investigated scientifically for their potential to boost male fertility, including one more associated with female sexual health than male fertility.

These include:

• Fish oil/Omega-3s
• Folic acid — much more associated with women, especially in relation to fertility
• Zinc
• Antioxidants

These nutrients can come from your diet, but it is also possible to supplement your intake, too.

Do male fertility supplements work?

Inverse spoke with Charles Muller, the director of the Male Fertility Lab at the University of Washington. He has been studying sperm and fertilization for decades. When asked about male fertility supplements, he did have a story to tell.

He had two patients, one from India and one from China, who came to the Fertility Lab for assessment after struggling to conceive. Both had a condition called cryptozoospermia, wherein their semen had incredibly low sperm counts. This condition makes the possibility of fertilization very low.

Both men were treated with medicinal formulas in their home countries for several months, and upon returning to the lab, their sperm counts were high.

"Now, the question is, is that just sort of a random event? Or did these herbal supplements really help them?" Muller wonders.

He says that while there are studies of the types of male fertility supplements commonly touted in the United States, "randomized, placebo controlled clinical trials basically don't exist in this area." These kinds of trials are the 'gold standard' for sussing out whether any medication or intervention is truly effective.

He also says male fertility studies are complicated by the fact semen samples are extremely variable across populations, and even when taken from the same individual.

To really establish whether a supplement is capable of positively changing semen quality on the population level, a researcher would have to establish a "normal range" for each evaluated semen parameter for each individual in the study.

"There's a blood-testes barrier"

Even if, theoretically, you have a condition that could benefit from supplementation, the compounds in the supplements may not be able to get where they need to go, Muller says.

"It's possible those things don't have any effect whatsoever, because they're just getting thrown out by the digestive system, or second, it's possible they're never making their way into the testes," Muller says.

"Bioavailability in the testes is very limited, because very little can get into the testes. There's a blood-testes barrier."

These issues notwithstanding, Muller says: "I don't knock people doing initial trials. I do them too, because you might find out if it is worth looking into further."

What are the best male fertility supplements, according to science?

The results from the existing studies are mixed. Here is a synopsis of some of the research:

· Fish oil for men:

A recent study of young, Danish military recruits found that Omega-3 supplementation improved sperm health. Inverse previously reported that 98 of 1,679 men evaluated in the study took fish oil as a supplement and they had higher sperm count, semen volume, and testicle size than those who did not.

Muller says that, while this study is promising, it was "uncontrolled in terms of amount of omega-3 and patient selection" — two major limitations to taking the results at face value. The study authors highlight this issues, too, saying "these findings need confirmation in well-designed randomized clinical trials among unselected men."

Ultimately, the jury is still out on fish oil supplements for men's fertility, but these preliminary results are promising.

· Folic acid for male fertility:

Folic acid is often billed as an essential supplement for female fertility and sexual health, but what about male fertility?

A meta-analysis of seven studies found sperm concentrations were higher in men who took folate supplements than those who ingested a placebo. How well sperm swam and whether they were the optimal shape and size were not shown to be correlated with folate supplementation.

The study authors concluded: “these results should be interpreted with caution due to the important heterogeneity of the studies included in this meta-analysis. Further trials are still needed to confirm the current findings.”

Inverse also recently covered a large male fertility study which followed 2,300 male partners from couples planning to undergo infertility treatment. The men were divided in half and one group of 1,150 took 30 milligrams of elemental zinc and 5 milligrams of folic acid daily, while the other group took a placebo. After 6 months, both groups had similar birth rates. The researchers concluded, "these findings do not support the use of folic acid and zinc supplementation by male partners for the treatment of infertility."

· Zinc for men:

Both studies above involve zinc supplementation along with folic acid. Zinc is one of the most popular ingredients in dietary supplements for male fertility, according to a 2020 paper in the journal Nutrients. Overall, it appears to be in some 70 percent of the tested supplements.

Some scientists argue zinc is an essential nutrient for safeguarding male fertility and reproductive health. But as the 2020 paper above argues, the standards for testing how well any one supplement are lacking. And for zinc, the lack of standards can be worrying.

As the authors write in the Nutrients review: "We were surprised to point out that all RCTs and meta-analyses on zinc for male infertility relied on doses always exceeding the UL."

In other words, many of the tests for zinc supplementation they looked at had doses of zinc which were above the upper recommended intake. Too much zinc can have adverse side affects, they write, sounding a note of caution over this supplement's supposed benefits.

· Antioxidants:

Antioxidants benefit the body by neutralizing free radicals — metabolic waste products which can wreak havoc on cellular health if not properly disposed of. Free radicals can kill sperm and they can also result in the fragmentation of sperm DNA, which could potentially lead to the loss of a pregnancy or even childhood cancer, according to Muller.

Because of this, antioxidant supplementation has and is being investigated as a way to boost sperm health. One 2016 meta-analysis of four clinical trials found a combination of antioxidant supplements including vitamin C, vitamin E, and CoQ10, "can effectively improve semen parameters in infertile men."

A clinical study in which participants took a daily antioxidant formulation comprised of vitamin C, vitamin E, selenium, l-carnitine, zinc, folic acid, and lycopene for three to six months found otherwise, however. This study found no benefits for sperm DNA integrity or other semen parameters.

Additionally, some researchers express concern excess antioxidant use could damage fertility through a different process than the damage caused by free radicals. Because of this potential, the researchers write, "we feel that there is a need for more elaborate research to establish the clear benefits and risks involved in antioxidant therapy for male infertility."

How do you know you need male fertility supplements?

The science is still out on whether these supplements work.

But according to the Mayo Clinic, infertility is a common problem, affecting one in seven couples. They define infertility as the inability to conceive after a year or more of frequent, unprotected sex.

According to the Mayo Clinic, the following factors are crucial for fertilization to be successful:

• Your sperm must be healthy
• There needs to be enough of them: Low sperm count decreases the probability of fertilization
• They need to be effectively transported out of your body: There are a series of delicate tubes and organs involved in the creation, maintenance, and transport of sperm and semen
• They must be able to move: Sperm motility is a major issue. If they are not moving correctly, they may not be able to travel to the egg cell

These attributes of successful fertilization can be disrupted by factors such as:

• Infection
• Retrograde ejaculation (semen enters the bladder during orgasm instead of exiting the body)
• Auto-immunity conditions
• Previous surgeries
• Undescended testicles
• Hormone imbalances
• Cancer
• Chromosomal abnormalities (such as possessing an extra X chromosome)
• Medications including: SSRI’s, channel blockers, and certain antibiotics
• Physiological abnormalities in the reproductive tract that prevent the transport of semen or sperm
• Celiac disease
• Varicocele (swelling of veins in the testicle)
• Cystic fibrosis or possessing one of the of the genes that causes cystic fibrosis

While many of these issues can be medically addressed, there are causes of male infertility, such as missing parts of the reproductive tract, that are hard to imagine being effectively treated with supplements.

Can you get the nutrients in male fertility supplements from your diet?

Whether or not they work as supplements, omega-3s, folic acid, zinc, and many antioxidants can come from dietary sources.

Additionally, a recent study found correlations between diet and sperm count, and established a kind of diet hierarchy.

Listed from highest to lowest correlated sperm counts, the investigated diets were:

· “Prudent” diet: The researchers described this as a “generally healthy” diet, consisting of fruits, vegetables, fish, and chicken. This bears a lot of similarity to the Mediterranean diet, the benefits of which Inverse has reported on before.

· Vegetarian-like diet: Limited meat and plenty of vegetables, eggs, and dairy.

· Open-sandwich diet: Traditional Danish diet including cold cuts, whole grains, and dairy.

· Western diet: Lots of red meat, fried food, and sugary drinks, and deserts.

Feiby Nassan, a co-author on the study and researcher at the Harvard T.H. Chan School of Public Health, previously told Inverse that “because following a generally-healthy diet pattern is a modifiable behavior, our results suggest the possibility of using dietary intervention as a possible approach to improve sperm quality of men in reproductive age.”

Muller agrees diet is an important factor in sperm health and questions about diet are included on the UW Male Fertility Lab intake form. Specifically, Muller’s team looks out for diets low in omega-3s or high in nitrates.

Ultimately, following a Mediterranean diet may be the best recipe for male fertility health, these data suggest. For more information on the diet's scientific backing, take a look at these four mental and physical health benefits.

How long do male fertility supplements take to work?

This is a difficult question to answer given the dearth of reliable studies showing they work at all.

However, the Cleveland Clinic website quotes Cleveland Clinic urologist and male fertility specialist, Neel Parekh, as saying that, for men with male oxidative stress infertility (MOSI), which is a condition where there are more free radicals than antioxidants in the semen, "taking supplemental antioxidants for three months or longer can improve sperm parameters. If a patient doesn’t have MOSI, however, taking antioxidants may do more harm than good.”

He also clarifies that this is only the case for men who don't have other contributing infertility issues.

Muller says it takes about three months for a stem cell to develop into a sperm cell, and so a supplement study should be at least that long.

Some of the studies have found positive effects of supplementation featured trial periods ranging from 8 to 26 weeks.

Can male fertility supplements hurt your fertility?

Counterintuitively, testosterone supplementation can reduce sperm count.

According to Muller, while testosterone is necessary for the production of sperm, increasing blood testosterone levels through supplementation (or steroid use) can drive sperm production down because of a negative feedback loop involving the hypothalamus in the brain.

When the hypothalamus detects increased testosterone levels in the blood, it down regulates the production of other important hormones called LH and FSH. When the testes start getting less LH, they reduce their own testosterone production. This is significant because healthy testosterone levels in the testes should be ten times what they are in the blood stream.

“If the testes itself is not making testosterone, it's going to have the same level as in the blood, which is a 10th of what it needs to stimulate sperm production,” Muller says.

Other lifestyle factors known to potentially reduce fertility are:

· Frequent hot tub/sauna use

· Marijuana use

· Diet low in omega-3s

· Exposure to industrial or environmental toxins at work or in the home including: plasticizers, xylene, toluene

The Inverse analysis — While there is reason to believe that certain kinds of supplementation or traditional herbal formulas could be helpful, that certainly doesn’t mean that anything advertised as boosting male fertility is efficacious or safe.

Fertility can be impacted by myriad factors such as overall health, habits, and environmental stressors which may need to be resolved. If you’re having trouble conceiving, a first step is to get to a specialist and get some analysis done before you start popping pills.