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Men's Vitality GuideWhat the evidence actually supports for men's vitality
Three things have randomised evidence behind them and none of them is sold in a bottle: sleep, alcohol and movement.
After that comes a short list of ingredients with real human trials — maca, ashwagandha, arginine — at doses measured in hundreds or thousands of milligrams, and a longer list with traditional use and little else. Knowing which list an ingredient is on is most of what a buyer needs.
A guide to the category rather than to a product, written so it is still useful to somebody who buys nothing.
Start with the three things that are not supplements
This is the unglamorous part and it is also the part with the best evidence, so it goes first rather than in a footnote.
Sleep. Short sleep affects mood, recovery, appetite and interest, and it is the single most common unaddressed factor in men who feel their energy has gone. Nobody sells it, which is roughly why nobody talks about it.
Alcohol. A depressant with a well-described effect on sleep architecture and on the circulatory and hormonal systems the whole aisle claims to support. Reducing it is free and works faster than anything on a shelf.
Movement. Regular activity improves endothelial function, which is the same mechanism the arginine in half these products is sold for. Thirty minutes of walking a day is not a marketing claim; it is the thing the marketing claims are imitating.
If those three are not in order, a supplement is being asked to compensate for them and it will not. If they are in order, a supplement is a small addition at the margin, which is a reasonable thing to want and a reasonable thing to buy.
The ingredients with real human trials
| Ingredient | What was measured | At what daily dose |
|---|---|---|
| Maca | Sexual desire in healthy men, improved from week eight and independent of serum testosterone (Gonzales 2002, Andrologia); subjective sexual well-being in men with mild erectile dysfunction (Zenico 2009, Andrologia) | 1,500–3,000 mg of maca alone |
| Ashwagandha | Perceived stress, anxiety and morning cortisol (Lopresti 2019, randomised trial, 2024 systematic review and meta-analysis, Explore) | 240–600 mg of a standardised extract |
| L-Arginine | Blood pressure and nitric-oxide metabolism (Khalaf 2019, Nutrients, Schwedhelm 2008, Br J Clin Pharmacol) | Gram-scale intakes |
| Green tea catechins | Vascular function and a modest blood-pressure effect (Moore 2009, Br J Nutr, Peng 2014, meta-analysis of 13 trials) | Catechin intakes well above a gummy |
| Caffeine | Alertness, well characterised (FDA consumer update) | 80–100 mg is a cup of coffee |
Every figure in the third column is the dose that research used. None of them is a recommendation, and none describes any particular product.
Two things follow. The first is that the effective doses in this table are large relative to what fits in a gummy or a single capsule, which is the central tension of the whole category. The second is that a product naming one of these ingredients is not thereby delivering the amount the research used, and the only way to know is a panel that prints a number.
The ingredients with tradition and little else
Muira puama, catuaba and several others reach this aisle on long traditional use rather than on modern trials. That is not nothing — a plant taken for generations in a particular way carries real information — but it is a different kind of evidence and it should be labelled as such. NCCIH is the sensible neutral starting point.
Tribulus terrestris deserves its own line because it is the clearest example of marketing outrunning evidence in this category. It has been sold for decades on a testosterone story; a 2025 systematic review, Nutrients of clinical trials in men found the evidence for erectile function mixed and the evidence for raising testosterone weak. An honest label can name it. An honest label cannot imply what it does.
Horny goat weed sits somewhere between the two lists. Its active, icariin, is a weak PDE5 inhibitor with real laboratory characterisation (Shindel 2010, J Sex Med), and it also carries the interaction profile that matters most in this aisle (MedlinePlus). An ingredient worth naming, and worth naming carefully.
What a buyer should actually do with all this
Fix the three free things first, or accept that you have not
Not as a moral point. As a measurement point: if sleep is a mess, you will not be able to tell what the supplement did.
Decide whether you want one ingredient or several
One ingredient at the trial dose is the evidence-led choice. Several at small amounts is the adherence-led choice. Both are defensible and they answer different questions.
Read the panel, not the front of the bottle
The panel is the regulated statement and it is frequently longer than the advertising. The checklist in the companion guide takes about two minutes.
Give it four weeks and write down what changed
Nothing botanical works in a week. Score three things before you start and score them again at the end of week four.
Talk to a prescriber if you take anything
Especially a nitrate, a blood-pressure medicine or a PDE5 inhibitor. This is the one step in the list that is not optional.
Sources for this guide
- Gonzales GF, Cordova A, Vega K, et al. Effect of Lepidium meyenii (MACA) on sexual desire and its absent relationship with serum testosterone levels in adult healthy men. Andrologia. 2002 Dec. Randomized controlled trial. https://pubmed.ncbi.nlm.nih.gov/12472620/
- Zenico T, Cicero AFG, Valmorri L, Mercuriali M, Bercovich E. Subjective effects of Lepidium meyenii (Maca) extract on well-being and sexual performances in patients with mild erectile dysfunction: a randomised, double-blind clinical trial. Andrologia. 2009 Apr. https://pubmed.ncbi.nlm.nih.gov/19260845/
- Shin BC, Lee MS, Yang EJ, Lim HS, Ernst E. Maca (L. meyenii) for improving sexual function: a systematic review. BMC Complementary and Alternative Medicine. 2010 Aug 6. https://pubmed.ncbi.nlm.nih.gov/20691074/
- Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: a randomized, double-blind, placebo-controlled study. Medicine (Baltimore). 2019 Sep. https://pubmed.ncbi.nlm.nih.gov/31517876/
- Effects of Ashwagandha (Withania somnifera) on stress and anxiety: a systematic review and meta-analysis. Explore (New York). 2024 Nov-Dec. https://pubmed.ncbi.nlm.nih.gov/39348746/
- National Institutes of Health, Office of Dietary Supplements. Ashwagandha: is it helpful for stress, anxiety, or sleep? Fact sheet for health professionals. https://ods.od.nih.gov/factsheets/Ashwagandha-HealthProfessional/
- Schwedhelm E, Maas R, Freese R, et al. Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism. British Journal of Clinical Pharmacology. 2008. https://pmc.ncbi.nlm.nih.gov/articles/PMC2291275/
- Khalaf D, Kruger M, Wehland M, Infanger M, Grimm D. The effects of oral l-arginine and l-citrulline supplementation on blood pressure. Nutrients. 2019. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6683098/
- MedlinePlus, U.S. National Library of Medicine. L-arginine. https://medlineplus.gov/druginfo/natural/875.html
- Moore RJ, Jackson KG, Minihane AM. Green tea (Camellia sinensis) catechins and vascular function. British Journal of Nutrition. 2009 Dec. Review. https://pubmed.ncbi.nlm.nih.gov/19751534/
- Peng X, Zhou R, Wang B, Yu X, Yang X, Liu K, Mi M. Effect of green tea consumption on blood pressure: a meta-analysis of 13 randomized controlled trials. Scientific Reports. 2014. https://www.nature.com/articles/srep06251
- National Center for Complementary and Integrative Health. Green tea. https://www.nccih.nih.gov/health/green-tea
- U.S. Food and Drug Administration. Spilling the beans: how much caffeine is too much? https://www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much
- Effects of Tribulus (Tribulus terrestris L.) supplementation on erectile dysfunction and testosterone levels in men: a systematic review of clinical trials. Nutrients. 2025 Apr 6. https://pubmed.ncbi.nlm.nih.gov/40219032/
- Shindel AW, Xin ZC, Lin G, et al. Erectogenic and neurotrophic effects of icariin, a purified extract of horny goat weed (Epimedium spp.) in vitro and in vivo. Journal of Sexual Medicine. 2010. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1743-6109.2009.01699.x
- MedlinePlus, U.S. National Library of Medicine. Epimedium (horny goat weed). https://medlineplus.gov/druginfo/natural/699.html
- National Institutes of Health, Office of Dietary Supplements. Dietary supplements for exercise and athletic performance. Fact sheet for health professionals. https://ods.od.nih.gov/factsheets/ExerciseAndAthleticPerformance-HealthProfessional/
- National Center for Complementary and Integrative Health. Dietary and herbal supplements. https://www.nccih.nih.gov/health/dietary-and-herbal-supplements
