The bottom line
Human evidence consists of a handful of small randomised trials (testosterone, muscle fatigue, collagen and bone markers, fracture healing), mostly using one patented purified extract and often funded or supplied by its manufacturer; results are encouraging but unreplicated, and a 2023 systematic review graded shilajit only 'possibly effective' for raising testosterone in late-onset hypogonadism. Claims for fatigue, cognition, immunity and antioxidant effects rest mainly on animal and laboratory work, and an independent review concluded that much of the bioactivity of shilajit 'lacks substantial evidence'.
RCTEvidence: limited
Testosterone (healthy middle-aged men)
Randomised, double-blind, placebo-controlled; 96 men aged 45-55 enrolled, 75 completed (38 shilajit, 37 placebo); purified shilajit extract (PrimaVie) 250 mg twice daily vs placebo for 90 days
Total testosterone, free testosterone and DHEA-S at day 90 were significantly higher than placebo (total testosterone about +20% from baseline in the shilajit group); LH was maintained and FSH rose.[10]
Limitations: Single small trial, per-protocol analysis (21 dropouts excluded); groups differed at baseline (placebo baseline total testosterone 5.82 vs 4.84 ng/mL) and placebo values fell over time; analysed with t-tests; funded by the extract manufacturer (Natreon). Not replicated independently.
systematic reviewEvidence: limited
Testosterone (systematic review of 'testosterone boosters')
52 studies on 27 proposed testosterone boosters, outcome total testosterone vs placebo in athletes, late-onset hypogonadism, infertile and healthy men
Most products failed to raise total testosterone; purified shilajit extract (PrimaVie) was graded only 'possibly effective' for men with late-onset hypogonadism.[12]
Limitations: Rating for shilajit rests on very few trials; no pooled meta-analysis.
observationalEvidence: preliminary
Male fertility (oligospermia)
Single-arm, uncontrolled pre-post clinical study; 35 oligospermic men enrolled, 28 completed; processed shilajit 100 mg capsule twice daily for 90 days
Reported increases from baseline in total sperm count (+61.4%), motility, normal forms and serum testosterone (+23.5%), with lower semen malondialdehyde; liver and kidney tests unchanged.[11]
Limitations: No control group, small sample, completers only; improvements could reflect regression to the mean or other factors.
RCTEvidence: limited
Muscle fatigue / strength
63 recreationally active men randomised to 250 mg/day, 500 mg/day PrimaVie shilajit or placebo for 8 weeks (21 per group); isokinetic fatiguing protocol
In the upper-50th-percentile strength subgroup only, 500 mg/day was associated with a smaller fatigue-induced drop in maximal strength (8.9% vs 16.0% placebo) and lower baseline serum hydroxyproline; 250 mg/day did not differ from placebo.[13]
Limitations: Main effect found in post-hoc dichotomised subgroups rather than the whole sample; young men only; surrogate markers.
RCTEvidence: preliminary
Collagen synthesis biomarker
35 recreationally trained men; 500 mg/day or 1000 mg/day shilajit vs placebo for 8 weeks
Serum pro-c1α1 (type 1 collagen synthesis marker) increased significantly in both shilajit groups but not with placebo; more participants exceeded the minimal clinically important difference with 1000 mg (75%) than placebo (30%).[14]
Limitations: Small, short, biomarker outcome only; no clinical endpoint.
RCTEvidence: limited
Bone mineral density (postmenopausal osteopenia)
60 postmenopausal women aged 45-65 with osteopenia randomised to placebo, 250 mg or 500 mg standardised aqueous shilajit extract daily for 48 weeks
Lumbar spine and femoral neck BMD declined on placebo, and the decline was dose-dependently attenuated with shilajit (significant differences at 24 and 48 weeks); bone turnover markers, oxidative stress markers and hsCRP moved favourably.[15]
Limitations: Single-centre, small (about 20 per arm), single trial; no fracture outcomes; not independently replicated.
RCTEvidence: limited
Fracture healing
160 adults aged 18-60 after tibial shaft fracture surgery, three Tehran hospitals; two 500 mg capsules of momiai (shilajit) or placebo for 28 days
Mean time to radiographic union was 129 days with momiai vs 153 days with placebo (p < 0.049); adverse effects did not differ between groups.[16]
Limitations: Borderline significance; radiographic assessment; product characterisation and source differ from Indian purified shilajit.
RCTEvidence: preliminary
Skin microperfusion
Healthy middle-aged women; PrimaVie shilajit 125 mg or 250 mg twice daily vs placebo for 14 weeks; skin biopsies for gene expression
At 250 mg twice daily, skin perfusion improved vs baseline and placebo, and genes linked to endothelial migration, vessel growth and extracellular matrix were induced; no adverse effects reported in 14 weeks.[17]
Limitations: Mechanistic/transcriptomic endpoints; small; product supplied by the manufacturer.
These studies explain possible mechanisms. They do not show the same effect in people.
animalEvidence: preliminary
Chronic fatigue (animal model)
Rats, forced-swim model of chronic fatigue syndrome; standardised processed shilajit 25, 50, 100 mg/kg for 21 days
Shilajit reversed fatigue-like behaviours, modulated HPA-axis markers and preserved mitochondrial enzyme activity and membrane potential.[18]
Limitations: Animal model only; cannot be extrapolated to human fatigue.
in vitroEvidence: preliminary
Immune / complement activity of fulvic acid
Fractionated fulvic-acid extracts of commercial shilajit tested in complement-fixation assays
All fractions showed dose-dependent complement-fixing activity in vitro.[9, 6]
Limitations: Laboratory assay only; a separate review judged the immunomodulatory evidence for shilajit 'unproven' and its in vivo antioxidant studies to use irrelevant doses without positive controls.