Benefits
Testosterone support in middle-aged men
In a 90-day placebo-controlled trial in healthy men aged 45 to 55, PrimaVie® at 250 mg twice a day raised total testosterone, free testosterone and DHEAS more than placebo, while LH and FSH stayed steady. The maker supplied the extract, and no independent group has repeated the result, so treat it as one encouraging trial.
Sperm count and motility
In a small study without a placebo group, 28 men with low sperm counts finished 90 days of processed shilajit at 100 mg twice a day. Their total sperm count rose about 61%, and motility, normal sperm and testosterone also improved against their own starting values. Without a comparison group, these changes cannot be pinned on shilajit.
Muscle strength retention after fatiguing exercise
In an 8-week trial funded by Natreon, 63 recreationally active young men took PrimaVie® at 250 or 500 mg a day or placebo. Among the stronger half of the men, 500 mg a day led to a smaller drop in leg strength after a fatigue test, and among the men with the highest starting levels it lowered hydroxyproline, a collagen breakdown marker. The 250 mg dose did not differ from placebo.
Mechanism of action
Testosterone rise with steady LH and FSH
In the testosterone trial, LH and FSH, the pituitary hormones that signal the testes, stayed steady while testosterone rose. That pattern hints at an effect at the level of the testes, but the trial did not measure how this happens.
Lower oxidative stress markers in semen
In the sperm study, malondialdehyde, a marker of oxidative damage, fell by about 19% in semen, and shilajit compounds were detected in semen samples. This fits an antioxidant role, but the study had no placebo group.
Collagen and connective tissue signals
In the 8-week strength trial, 500 mg a day lowered blood hydroxyproline in the half of the men with the highest starting levels, which the authors read as less collagen breakdown. A separate biopsy study of an 8-week course found more activity in muscle genes tied to the extracellular matrix, the scaffold around muscle fibers.
Clinical trials
Randomized, double-blind, placebo-controlled trial; purified shilajit 250 mg twice a day for 90 days (Pandit et al. 2016, Andrologia)
Healthy men aged 45 to 55; trade press reports 75 men enrolled and PrimaVie® supplied by Natreon
Total testosterone, free testosterone and DHEAS rose significantly more than with placebo, and LH and FSH stayed steady. The abstract does not give the size of the changes. One trial, not yet repeated by an independent group.
Single-group study without a placebo; processed shilajit 100 mg twice a day for 90 days (Biswas et al. 2010, Andrologia)
35 men with sperm counts below 20 million per mL enrolled; 28 completed
Against their own starting values, total sperm count rose 61.4%, motility 12.4% to 17.4%, normal sperm 18.9% and serum testosterone 23.5%, while semen malondialdehyde fell 18.7%. Liver and kidney tests did not change. With no control group, the changes cannot be attributed to shilajit with confidence.
Randomized, placebo-controlled trial; 250 mg or 500 mg a day or placebo for 8 weeks (Keller et al. 2019, J Int Soc Sports Nutr)
63 recreationally active men, average age 21, 21 per group
In the stronger half of the men, the 500 mg group lost less strength after the fatigue test (8.9% drop) than the 250 mg (17.0%) and placebo (16.0%) groups. In the half with the highest starting hydroxyproline, 500 mg lowered this collagen breakdown marker. The 250 mg dose did not differ from placebo, the benefits appeared only in these split analyses, and Natreon funded the study.