Viasil Reviews: The natural performance enhancer for you?

Nearly a third of men experience erectile dysfunction at some point.¹ It can feel embarrassing in the heat of the moment, but there’s nothing to be ashamed of. And if you’re a man over 70 or take SSRIs for depression, the odds are even higher that you’ll develop symptoms like low libido or difficulty maintaining an erection. The good news is that there’s plenty of help out there. And many of those potential remedies don’t require a prescription, like Viasil, a nutritional supplement geared toward helping men address their sexual dysfunction.

Viasil tablets might be worth trying if you’re looking for a non-prescription way to address sexual performance issues without taking ED medications like Viagra. The product uses relatively potent extracts of ingredients that have performed well in a handful of small-scale research studies. The 100-day money-back guarantee gives you enough time to see if the product will work without risking too much money. However, you might want to pass on the scientifically unproven Instant Erection Gel.

For this review of Viasil, our team pored over more than 200 scientific research studies looking into male sexual dysfunction and the various interventions — both prescription and non-prescription — available to men. We then distilled those hundreds of hours of research into this review.

Additionally, like all health-related content on this website, this review was thoroughly vetted by one or more members of our Medical Review Board for accuracy. We’ll keep an eye on Viasil and the broader men’s health landscape as time goes on in order to keep this review and the rest of our critical men’s wellness information current.

Over the past two decades, Innerbody Research has helped tens of millions of readers make more informed decisions about living healthier lifestyles.

Viasil falls into a class of men’s sexual wellness supplements that we have extensive experience researching and reviewing for our readers. When we set out to apply our expertise to a given supplement in this particular niche, we take a few central criteria into account: effectiveness, safety, cost, and privacy. There are certainly other considerations besides these, but we consider these parameters to be the most important for the average man considering Viasil or one of its competitors.

Effectiveness is the biggest factor in our overall rating. It’s not that the other criteria don’t matter, but if a supplement doesn’t work, you’re not going to take it. Other issues cease to be important once you’ve moved on to a different product. In a close second behind effectiveness is safety. This is especially true in the men’s sexual wellness space, as no man wants to put his genitalia on the line, especially if the odds of success are low.

We also look into cost and privacy, specifically comparing Viasil’s price structure and privacy policies with those of its competitors. Given its specific combination of ingredients, Viasil has the potential to help some men who are looking for a non-prescription way to ameliorate certain problems in the bedroom, but it doesn’t offer the best value for its class. Its price point is on par with products like Semenax or Male Extra, but most of its ingredients appear in smaller doses. For example, Viasil relies primarily on a 700mg combination of pomegranate and sweet orange extracts, whereas Male extra delivers a 500mg dose of pomegranate extract in addition to large quantities of other ingredients, like zinc and L-arginine, for the same price.

Effectiveness

Rating: 6/10

Without a statistically significant study available looking at Viasil’s specific combination of ingredients, our measure of its potential efficacy has to come from elsewhere. Specifically, we examined the available research regarding all of its main ingredients, looking at things like the doses used in any studies that found efficacy and examining study methods, margins of error, and potential bias or conflicts of interest.

Central to Viasil’s formula is a combination of pomegranate and sweet orange extracts made by the BioActor pharmaceutical company and going by the brand name Actiful. The combination was developed with older patients in mind as a potential source of increased energy. A white paper on the product points to a handful of studies linking its ingredients with improved physical performance in active, trained subjects, as well as improved blood flow in overweight subjects.² The latter effect may be attributed to a particular citrus polyphenol that can stimulate the production of nitric oxide, at least according to a 2011 study.³

However, this study looked at a 500mg daily dose of the concentrated polyphenol derived from sweet orange, while the entire dose of Actiful in Viasil is 700mg and contains far more than just that one polyphenol. This isn’t to say it wouldn’t be effective at this dosage, but we would require studies conducted at the doses provided — and ideally in combination with Viasil’s other ingredients — to draw firmer conclusions.

Viasil’s other ingredients appear mostly as reasonably potent extracts that bring what look like small amounts closer to what the product’s competitors provide. But those doses are still on the low side. Compare Viasil’s 400mg (20mg of a 20:1 extract) to Performer 8’s 6,000mg of ginseng, and the difference is clear. The weakest dose, however, is the ingredient with the most promising research behind it. Viasil only provides you with 1.5mg of zinc picolinate. Other companies deliver 30-50mg of zinc (Male Extra: 45mg; Max Performer: 24mg) as part of ingredient lists that are more comprehensive.

Safety

Rating: 7/10

Viasil’s safety profile isn’t bad, primarily because it doesn’t use particularly high doses of any one ingredient. The company banks on the combination of ingredients working to provide results without clearly identifiable safety risks. But that doesn’t mean those risks aren’t there. In fact, just as a lack of research into Viasil’s specific combination of ingredients makes it difficult to ascertain its ultimate effectiveness, that research deficit obscures any potential claims of safety.

When we look at the individual components, we see ingredients that are mostly safe for most people. Studies looking into each have occasionally found recurrent adverse effects or a threat of contraindication with particular medications. For example, research into icariin — the beneficial component in horny goat weed extract — reveals a high potential for interactions with various drugs with as-yet-unknown consequences.⁴ And considering the compound’s ability to act like a PDE-5 inhibitor,⁵ there may be additional dangers to those with blood pressure issues.⁶

Less severe side effects are also not uncommon, including digestive discomfort, breathing problems, headache, and heart palpitations. These effects are not unique to Viasil; most male enhancement products have relatively similar safety profiles, offset only by moderate ingredient variety and dosage differences.

The best thing you can do before adding Viasil or any male enhancement product to your regimen would be to talk to your doctor and review all of your options.

Cost

Rating: 6/10

When we evaluate a product like Viasil’s cost, we take a little more than just the price tag into account, considering things like potential bulk or subscription savings, shipping costs, and any money-back guarantee available. Viasil doesn’t have a subscription platform, so the only way you can save money is by buying in bulk. A one-month supply of Viasil costs $60, but that cost per month comes down to $36 if you buy a five-month supply.

Here’s a look at how Viasil’s pricing compares with its top competitors:

As you can see, Viasil’s one-month supply price falls right in the middle of the market. The three-month supply is on the low end, however, which is a good thing. That three-month supply is a great place to start for most men, mainly because it can take up to three months for any effects to set in and because Viasil’s 100-day money-back guarantee lets you get to that three-month mark and still get most of your money back.

At its highest bulk tier, Viasil’s per-month price is a bit higher than competitors like Max Performer and Semenax and only $3 less than our top pick among male enhancement pills, Performer 8.

Privacy

Rating: 6/10

Companies like Viasil tend to have relatively similar privacy practices and policies. Most utilize cookies and web beacons to track the way you use their websites, what led you to the site, and where you go when you leave. This isn’t anything earth-shattering, but it’s interesting that Viasil is one of the few sites that does not offer any way to opt out of this process.

Some companies have phone numbers you can call or email addresses you can use to opt out of information gathering and sale. Others make it even easier by letting you click a button or two and be done with it. But all Viasil has is some advice on deleting cookies from your browser after you leave the site. This is pretty underwhelming as privacy policies go.

To protect your real-world privacy, Viasil abides by the same measures all serious male enhancement pill manufacturers use. The package you receive in the mail has no identifying marks or logos anywhere on it, and the return address on the shipping label also won’t give away what’s inside. We always appreciate this level of discretion, but it is par for the course.

Viasil is a men’s sexual wellness supplement produced by Health Nutrition Ltd. in the U.K. It contains a small list of botanical ingredients in addition to a minuscule dose of zinc and is taken in tablet form. In theory, Viasil tablets help men deal with issues in the bedroom by promoting better blood flow through increased nitric oxide production.

There’s also evidence that Viasil’s inclusion of sweet orange extract could help combat erectile issues caused by aging or SSRIs. A citrus sinensis animal study gave rats a 50 mg/kg extract of orange peels to reduce ED symptoms induced by SSRIs (Paxil in this case).⁸ There was a significant decrease in sexual behavior but some improvement in ED symptoms among the Paxil-treated rats. The dose discrepancy here makes it very difficult to draw firm conclusions beyond the fact that the extract appeared to cause some changes in sexual health and behavior. In practice, effects will vary pretty widely from man to man, especially considering factors like age, diet, and potential underlying conditions contributing to sexual dysfunction.

Viasil also produces an Instant Erection Gel, which is a form of topical L-arginine that the company claims can instigate vasodilation locally in the penis. We haven’t found much evidence to back up that claim, but we’ll get into that more deeply in a bit.

To get a better sense of how Viasil may or may not work for you, let’s take a closer look at its ingredients, their dosages, and how those ingredients perform in clinical studies.

Who could benefit from Viasil, and who probably won't

Based on the ingredients in Viasil, we believe older men stand the best chance of experiencing positive effects. Actiful was designed with people over 60 in mind and is the bulk of the active ingredient contained in the tablets.

If you’re experiencing a lower libido due to SSRIs, Viasil might be worth a look, as well, given a small but promising amount of research into several of its ingredients’ ability to address the adverse effects of antidepressants.

And remember that most of the studies cited utilized participants with sexual dysfunction. So if you’re someone with a healthy sexual function looking for a little boost, Viasil might not be much help for you.

Viasil’s Instant Erection Gel isn’t available for direct purchase. Instead, it’s included for free as part of a bundle with orders of two months or more. The company promises stronger erections in just 10-15 seconds when used in combination with Viasil tablets.

Unfortunately, a lack of clinical evidence and no data about efficacy or long-term safety make this a tough product to recommend.

Here’s a look at the gel’s ingredients:

• L-Arginine: the main active ingredient, a naturally occurring amino acid that encourages healthy blood flow and increased nitric oxide production when taken orally
• Water and Glycerine: the base of the gel
• Polysorbate 20: emulsifier safely used in beauty products to modify texture
• Sodium Hydroxide: a pH-balancer used in soaps and cosmetics (can cause skin irritation and allergic reactions)
• Carbomer: safe emulsifier and stabilizer
• Phenoxyethanol: a preservative to stop bacterial growth, safely used in cosmetics
• Imidazolidinyl Urea: a derivative of formaldehyde, safe in low doses (under 0.5% of total product mass), but linked to skin irritation and other side effects in about 1% of people, according to this imidazolidinyl review¹⁸

Who could benefit from Viasil Instant Erection Gel, and who probably won't

According to this clinical study of an alprostadil-based cream, topical gels have often been used to treat ED successfully.¹⁹ Nearly 33% of participants responded well to this topical testosterone cream, too.²⁰ But there are no studies about the effects of L-arginine as a topical for treating ED. There are also no studies about the long-term side effects and safety concerns of topicals for ED.

Considering that any topical you put on your skin is directly absorbed into the area, we recommend some caution to protect your sensitive parts. And we encourage you to talk to a doctor before trying it.

There’s a pretty good chance that Viasil is going to be safe for most men, especially men who aren’t on any other prescription medications and those who don’t have any history of cardiovascular risk or disease. The difficulty in assessing the product’s overall safety profile comes from the same place that impacts any real assertion about its efficacy: lack of research.

Some small-scale studies in humans and animals show relatively low occurrence of adverse reactions at doses higher than those used in Viasil, but the study populations are often too small to be convincing. Additionally, those studies almost always look at individual ingredients isolated from other influences. There is no study looking at the specific set of ingredients and doses used in Viasil.

What we gather from available research suggests that the ingredients in Viasil are associated with the following potential side effects:

• Low blood pressure
• Upper respiratory infection
• Diarrhea
• Nausea
• Vomiting
• Insomnia
• Nervousness
• Heart palpitations
• Headache

The greatest danger that ingredients in Viasil present is an interaction with blood pressure medications.²¹ Several ingredients in Viasil are intended to improve blood flow to the penis, but that often means widening blood vessels generally, which can lower blood pressure. If you’re already taking medication to control your blood pressure, this can complicate its efficacy and potentially threaten your life.

We don’t think that doses of Viasil’s individual ingredients are strong enough to be a cause for serious concern, but their interactions with one another are a mystery and will remain so until dedicated research is performed. In the meantime, the best thing you can do before taking Viasil or any male enhancement supplement would be to speak with your doctor.

A one-month supply of Viasil costs $59.99. Ordering more earns you free boxes and the bonus gel add-on, as outlined below.

Viasil used to offer a higher tier that was an eight-month supply complemented by four free boxes for a total of 12 months. This would have brought the best price per month down even lower than the $36 at which it currently sits, but the company has done away with this option. Most other male enhancement products offer a one-, three-, and five- or six-month supply option, with only a few extending out to a year, so the fact that Viasil no longer offers the year’s worth doesn't make it an outlier.

However, almost every male enhancement product we regard as potentially worth trying has come to offer free shipping on all ordering tiers. With Viasil, you only get free shipping on bulk orders; one-month supply orders incur an $8 shipping fee. There’s a good chance that Viasil might someday do away with this shipping fee since many of the most popular male enhancement pills used to use the same model with free shipping available only for bulk orders. They’ve since adapted, perhaps due to a realization that the shipping charge was scaring off potential one-month customers at a greater rate than it was driving purchases up the tier structure.

100-day money-back guarantee

One of the things that makes Viasil a fair value is the way the company has structured its money-back guarantee. It gives you three months to try the product and decide if it’s right for you. If not, you can get a full refund minus any shipping charges you may incur. Some similar products offer shorter guarantees or only refund you for unopened products, but Viasil gives you a refund for all the boxes you order, regardless of their status. It still isn’t the best guarantee among male enhancement pills (that title belongs to Performer 8’s lifetime guarantee), but it’s better than most.

Given how important sexual health is to most men, there seems to have always been a focus on medications and interventions that can maximize a man’s virility. And with ED being such a common ailment among men, it’s no surprise that there are so many pills, tools, and techniques out there claiming to rescue men from the brink of sexual misery.

Knowing where to start can be a challenge. We’ve covered this task for a handful of product categories in great detail, including guides to male enhancement pills, penis pumps, and online prescription services for ED and premature ejaculation. If a stranger contacted us and asked us to make as simple a recommendation as possible with no context and little nuance, we’d likely direct them towards prescription treatment first, especially considering the superior amount of research and real-world experience associated with them. Viasil likely wouldn’t end up getting included in that recommendation.

So, let’s take a look at some viable alternatives to Viasil if you want to take in the full breadth of your options before making a decision.

Male enhancement pills

We’ll start with male enhancement pills, the category to which Viasil belongs. Viasil is in the higher price range of similar supplements for ED and sexual wellness. You can find comparable products starting at about $40, with some topping $70 per bottle.

Many male enhancement pills contain similar ingredients as those seen in Viasil, but they often boast larger doses. Some of the ingredients you don’t see in Viasil have a fair bit of positive research behind them as well, like the ashwagandha in our top pick among male enhancement pills, Performer 8.

If you want to get a sense of the greater male enhancement pill landscape, check out our comprehensive guide. Here are a few highlights:

• Performer 8 is our best overall pick, thanks to generous doses of zinc²⁴ and ashwagandha to help boost testosterone.²⁵ It also comes with a lifetime guarantee.
• Extenze is our top budget pick if cost is your one and only concern. However, several athletic organizations ban DHEA, one of its main ingredients.²⁶
• Semenax is our top male enhancement pill recommendation for men looking to bolster their fertility.

As an umbrella category, male enhancement pills also encompass volume pills, which put their focus on fertility and semen volume, and testosterone boosters, which have less to do with blood flow to the penis and more to do with stimulating testosterone production in the testes.

Prescription ED medication

Many of the men looking into male enhancement pills are dealing with some form of ED, even if it’s relatively mild. There’s no shame here, as ED affects roughly a third of all men and a solid 25% under the age of 40.²⁷ ²⁸ With numbers like that, it’s no wonder the pharmaceutical industry poured so much money into the research and development of drugs like Viagra and Cialis.

But those aren’t the only drugs available to treat ED, and there are generic forms of many ED medications that have brought their prices down significantly in recent years. The ED medications you’ll find from our preferred sources include:

• Viagra
• Cialis
• Stendra
• Sildenafil (generic for Viagra)
• Tadalafil (generic for Cialis)
• Vardenafil (generic for Levitra and Staxyn)
• Apomorphine

Add to that the relatively young revolution in telehealth, and you find an environment in which you can get a prescription for ED medications without ever leaving the house and have it shipped to your door directly.

There are some shady companies out there offering poorly made generic copies of popular ED medications, and we advise you to avoid such companies at all costs. In our research, we’ve uncovered a handful of great sources for ED medications, especially for men without insurance or those who want to enjoy as much privacy as possible in obtaining their drugs.

Here’s a quick look at our favorite online providers for ED medication.

Penis pumps

Penis pumps aren’t something we would typically recommend to a man who’s just begun to experience ED issues and doesn’t know where to turn. But if you genuinely want to avoid prescription drugs and don’t like your odds with less-tested supplements, pumps might be a good option. They’re also a common starting point for men who have lost size or function in the penis after a radical prostatectomy.

That last point doesn’t mean that penis pumps can make your penis larger. Men who undergo radical prostatectomies sometimes have their penises recede into their bodies somewhat.³⁰ It’s a disconcerting phenomenon, but studies into penis pump efficacy have shown a tendency for the therapy to return such men’s penises to normal size and function.

The trouble with penis pumps compared to supplements or prescriptions is the inconvenience. It takes time for a pump to create an erection by pulling blood into the penis. The process can be quite uncomfortable, and while some models let you use water to increase the comfort level, that means you have to use them in the shower or risk making a significant mess.

Still, penis pumps serve a particular niche, and they serve it well. Our complete guide gets into the nuances of a handful of models, but the most commonly recommended brand throughout our piece is Bathmate. Bathmate pumps can be used with or without water, and they boast some of the best build quality around.

1. Gerbild, H., Larsen, C. M., Graugaard, C., & Josefsson, K. A. (2018). Physical activity to improve erectile function: A systematic review of intervention studies. Sexual Medicine, 6(2), 75-89. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5960035/

2. BioActive B.V. Superfruit Complex for Active Living and Vitality. https://mcusercontent.com/8cb888356799f79b22af266b6/files/c95df64f-064f-a3fe-8c05-876d22a1581f/Actiful_White_Paper_2023_.pdf

3. Rizza, S., Muniyappa, R., Iantorno, M., Chen, H., Pullikotil, P., Senese, N., Tesauro, M., Lauro, D., Cardillo, C., & Quon, M. J. (2011). Citrus polyphenol hesperidin stimulates production of nitric oxide in endothelial cells while improving endothelial function and reducing inflammatory markers in patients with metabolic syndrome. The Journal of Clinical Endocrinology and Metabolism, 96(5), E782. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3085197/

4. Cao, F., He, R., Cao, J., Chen, X., Huang, T., & Liu, Y. (2011). Drug-drug interactions potential of icariin and its intestinal metabolites via inhibition of intestinal UDP-glucuronosyltransferases. Evidence-based Complementary and Alternative Medicine: ECAM, 2012. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3479967/

5. Ning, H., Xin, Z. C., Lin, G., Banie, L., Lue, T. F., & Lin, C. S. (2006). Effects of icariin on phosphodiesterase-5 activity in vitro and cyclic guanosine monophosphate level in cavernous smooth muscle cells. Urology, 68(6), 1350–1354. https://pubmed.ncbi.nlm.nih.gov/17169663/

6. Oliver, J.J., Melville, V.P., & Webb, D.J. (2006, August 28). Effect of regular phosphodiesterase type 5 inhibition in hypertension. Hypertension, 48(4). https://www.ahajournals.org/doi/10.1161/01.HYP.0000239816.13007.c9

7. Forest, C. P., Padma-Nathan, H., & Liker, H. R. (2007). Efficacy and safety of pomegranate juice on improvement of erectile dysfunction in male patients with mild to moderate erectile dysfunction: A randomized, placebo-controlled, double-blind, crossover study. International Journal of Impotence Research, 19(6), 564–567. https://pubmed.ncbi.nlm.nih.gov/17568759/

8. Ademosun, A. O., Adebayo, A. A., & Oboh, G. (2019). Orange peels modulate antioxidant markers and key enzymes relevant to erection in the penile tissue of paroxetine-treated rats. Andrologia, 51(9), e13371. https://pubmed.ncbi.nlm.nih.gov/31347717/

9. Sovia, E., Harjono, R.S., Nurjatin, R.J., Amsara, W.D., & Rohmah, A.S. (2021, July 24). Effect of sweet orange and pomegranate peel extract combination on in vivo antidiabetic and wound healing activity. Atlantis Press. https://www.atlantis-press.com/proceedings/asmc-21/125959087

10. Prasad, A. S., Mantzoros, C. S., Beck, F. W., Hess, J. W., & Brewer, G. J. (1996). Zinc status and serum testosterone levels of healthy adults. Nutrition, 12(5), 344–348. https://pubmed.ncbi.nlm.nih.gov/8875519/

11. Zhang, Z. B., & Yang, Q. T. (2006). The testosterone mimetic properties of icariin. Asian Journal of Andrology, 8(5), 601–605. https://pubmed.ncbi.nlm.nih.gov/16751992/

12. Shindel, A. W., Xin, C., Lin, G., Fandel, T. M., Huang, C., Banie, L., Breyer, B. N., Garcia, M. M., Lin, S., & Lue, T. F. (2010). Erectogenic and neurotrophic effects of Icariin, a purified extract of horny goat weed (Epimedium spp.) in vitro and in vivo. The Journal of Sexual Medicine, 7(4 Pt 1), 1518. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3551978/

13. Kamenov, Z., Fileva, S., Kalinov, K., & Jannini, E. A. (2017). Evaluation of the efficacy and safety of Tribulus terrestris in male sexual dysfunction: A prospective, randomized, double-blind, placebo-controlled clinical trial. Maturitas, 99, 20–26. https://pubmed.ncbi.nlm.nih.gov/28364864/

14. Santos, C. A., Jr, Reis, L. O., Destro-Saade, R., Luiza-Reis, A., & Fregonesi, A. (2014). Tribulus terrestris versus placebo in the treatment of erectile dysfunction: A prospective, randomized, double blind study. Actas Urologicas Espanolas, 38(4), 244–248. https://pubmed.ncbi.nlm.nih.gov/24630840

15. Jang, J., Lee, M. S., Shin, C., Lee, C., & Ernst, E. (2008). Red ginseng for treating erectile dysfunction: A systematic review. British Journal of Clinical Pharmacology, 66(4), 444-450. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2561113/

16. Qi, W., Wang, Z., Du, J., Zhang, Y., Calway, T., & Yuan, S. (2011). Metabolism of Ginseng and its Interactions with Drugs. Current Drug Metabolism, 12(9), 818. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291795/

17. Cohen, A. J., & Bartlik, B. (1998). Ginkgo biloba for antidepressant-induced sexual dysfunction. Journal of Sex & Marital Therapy, 24(2), 139–143. https://pubmed.ncbi.nlm.nih.gov/9611693/

18. National Cancer Institute. (2003, September). Imidazolidinyl urea. https://ntp.niehs.nih.gov/ntp/htdocs/chem_background/exsumpdf/imidazolidinylurea_508.pdf

19. Anaissie, J., & Hellstrom, W. J. (2015). Clinical use of alprostadil topical cream in patients with erectile dysfunction: A review. Research and Reports in Urology, 8, 123-131. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4977016/

20. Schultheiss, D., Hiltl, D. M., Meschi, M. R., Machtens, S. A., Truss, M. C., Stief, C. G., & Jonas, U. (2000). Pilot study of the transdermal application of testosterone gel to the penile skin for the treatment of hypogonadotropic men with erectile dysfunction. World Journal of Urology, 18(6), 431–435. https://pubmed.ncbi.nlm.nih.gov/11204264/

21. Shawish, M. I., & Wright, J. M. (2018). Effect of phosphodiesterase 5 inhibitors on blood pressure. The Cochrane Database of Systematic Reviews, 2019(12). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6914385/

22. Andersson, E. (2018). PDE5 inhibitors – pharmacology and clinical applications 20 years after sildenafil discovery. British Journal of Pharmacology, 175(13), 2554-2565. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6003652/

23. Ueda P., Mercer C.H., Ghaznavi C., & Herbenick D. (2020). Trends in frequency of sexual activity and number of sexual partners Among Adults Aged 18 to 44 Years in the US, 2000-2018. JAMA Network Open, 3(6), 203833. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2767066

24. Hunt, C.D., Johnson, P.E., Herbel, J., & Mullen, L.K. (1992). Effects of dietary zinc depletion on seminal volume and zinc loss, serum testosterone concentrations, and sperm morphology in young men. The American Journal of Clinical Nutrition, 56(1), 148–157. https://academic.oup.com/ajcn/article-abstract/56/1/148/4715610Lopresti, A. L., Drummond, P. D., & Smith, S. J. (2019). A randomized, double-blind, placebo-controlled, crossover study examining the hormonal and vitality effects of ashwagandha (Withania somnifera) in aging, overweight males. American Journal of Men's Health, 13(2). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6438434/

25. U.S. Anti-Doping Agency. (2021, May 14). What Should Athletes Know about DHEA? https://www.usada.org/spirit-of-sport/athletes-know-about-dhea/

26. Gerbild, H., Larsen, C. M., Graugaard, C., & Josefsson, K. A. (2018). Physical activity to improve erectile function: A systematic review of intervention studies. Sexual Medicine, 6(2), 75-89. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5960035/

27. Capogrosso, P., Colicchia, M., Ventimiglia, E., Castagna, G., Clementi, M.C., Suardi, N., Castiglione, F., Briganti, A., Cantiello, F., Damiano, R., Montorsi, F., & Salonia, A. (2013, July 1). One patient out of four with newly diagnosed erectile dysfunction is a young man—Worrisome picture from the everyday clinical practice. The Journal of Sexual Medicine, 10(7), 1833-1841. https://www.jsm.jsexmed.org/article/S1743-6095(15)30428-8/fulltext

28. Munk, N. E., Knudsen, J. S., Comerma-Steffensen, S., & Simonsen, U. (2019). Systematic review of oral combination therapy for erectile dysfunction when phosphodiesterase type 5 inhibitor monotherapy fails. Sexual Medicine Reviews, 7(3), 430–441. https://pubmed.ncbi.nlm.nih.gov/30711478/

29. Lin, H., & Wang, R. (2013). The science of vacuum erectile device in penile rehabilitation after radical prostatectomy. Translational Andrology and Urology, 2(1), 61-66. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4708600/