Shilajit
The verdict
A few small, manufacturer-funded human trials show promising sperm/testosterone effects; as a mineral product its heavy-metal risk is a sourcing/geology issue, not a processing one — third-party heavy-metal testing matters more here than for any other item in this list.
A mineral-rich substance exuded from Himalayan rock strata, widely sold across India as a male vitality/fertility supplement. Mineral, not botanical — its contamination pathway is geological sourcing, not herb processing.
What the evidence shows
A small trial (28 oligospermic men) reported +61% sperm count, improved motility, and reduced oxidative-stress markers over 90 days. A separate double-blind trial (96 healthy men) reported ~20% increases in total and free testosterone.
Both trials used PrimaVie®, a patented shilajit extract owned by Natreon, Inc. — a direct manufacturer conflict of interest that should be disclosed alongside the findings. Sample sizes under 100 in each; no independent, non-industry-funded replication found.
No herb-specific liver-injury case series or LiverTox entry found in this pass — but given the mineral-contamination pathway, third-party heavy-metal testing matters more here than for any other item in this list.
Evidence tier
Contamination risk🔴 Heavy-metal or adulteration risk tied to the product category (sourcing/manufacturing), not the item's own pharmacology.
Sources
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Last reviewed .