💗Sexual Health

An 8-week double-blind trial in 76 men with mild erectile dysfunction found that 300mg ashwagandha root extract twice daily significantly improved IIEF scores across all domains including erectile function, desire, and satisfaction compared to placebo.

A 32-week double-blind RCT in 238 infertile men found EPA+DHA supplementation (1.84 g/day) significantly increased sperm count and concentration compared to placebo. Applies only to men with pre-existing oligoasthenoteratospermia.

A 12-week RCT in 160 men with ED and dyslipidemia found oral niacin up to 1,500 mg/day significantly improved IIEF-Q3 and Q4 scores versus placebo; effect was significant in moderate-to-severe ED subgroup. Generalizability is limited to men with concurrent dyslipidemia.

A 6-month double-blind RCT in 175 infertile men found Proxeed Plus (containing L-carnitine and L-acetylcarnitine among other ingredients) significantly improved sperm motility and vitality. Because the product was a multi-ingredient formula, the effect cannot be attributed to L-carnitine alone, lowering confidence in the isolated attribution.

A 2025 meta-analysis of nine randomized trials in 781 infertile men found CoQ10 supplementation significantly improved sperm concentration, motility, and seminal volume, with the largest gains in trials lasting more than three months.

A 12-week trial in 57 healthy men found maca improved self-reported sexual desire without changing testosterone levels, though the study measured sexual desire, not physical stamina.

A 1998 double-blind trial in 69 men with low sperm motility found selenium significantly improved motility (p=0.023) versus placebo; 11% of selenium-treated men achieved paternity against 0% of placebo, though only 56% of treated men responded.

A small 4-week RCT (n=30) found magnesium supplementation increased free and total testosterone in both athletes and sedentary men; however, the exercise-training co-intervention in the athlete groups makes it impossible to isolate magnesium's contribution.

A pooling of three small randomized trials found alpha-lipoic acid improved sperm motility, concentration, and shape compared to other treatments in infertile men, though the evidence base is small and comparator arms varied across trials.

A small single-blind crossover trial (n=24 men with mild ED) found that L-citrulline 1.5 g/day improved erection hardness in 50% of participants vs 8% on placebo; single-blind design and tiny sample limit confidence.

A 2-month double-blind trial in 68 infertile men found that 2.5ml of Nigella sativa oil twice daily significantly improved sperm count, motility, and morphology compared to placebo; this is a single small trial from one center.

A 2021 meta-analysis of only 3 small RCTs (431 infertile men total) found NAC significantly improved sperm concentration and other semen parameters; testosterone and other hormones were not changed. Low quality because few trials underlie the pooled estimate.

A 6-month double-blind RCT in 45 men with age-related testosterone decline found Tongkat Ali improved IIEF-5 erectile function scores and total testosterone, with the largest gain in the group that also exercised; the authors noted the absence of a standalone supplement-only arm as a limitation.

A 26-week double-blind RCT found folic acid plus zinc increased sperm concentration in subfertile men; testosterone was not affected, and the combination design means it is impossible to attribute the sperm effect to zinc alone.

The large FAZST trial (n=2370) found that folic acid supplementation combined with zinc did not improve semen quality on any measured parameter or live birth rate; important caveat is that folic acid was never tested alone, so its independent effect on sperm is unknown.

A 4-month double-blind RCT in 66 middle-aged men found resveratrol did not change total testosterone, free testosterone, or DHT at either tested dose, despite lowering upstream androgen precursors.

A 124-person double-blind RCT found that 400 IU Vitamin E daily for 8 weeks produced no significant improvement in any measured sperm parameter or IVF outcome compared to placebo in infertile men.

A 12-week double-blind trial in 45 resistance-trained men found that 5g/day creatine monohydrate did not significantly change testosterone or dihydrotestosterone compared to placebo.

A 2026 meta-analysis of 27 RCTs found that Vitamin D supplementation produces no statistically clear or reproducible effect on total testosterone or any other androgen bioavailability marker; GRADE certainty was rated low for testosterone and very low for free testosterone.

A small 7-week trial in 19 male bodybuilders found that 2.5mg boron daily had no significant effect on plasma testosterone; the study was underpowered and in a healthy athletic population, making it hard to generalise.