Abstract Summary
Objective
To determine which form and standardization of ashwagandha is best supported by human evidence for increasing serum testosterone in men, and to summarize contexts, doses, and outcomes across clinical trials.
Context
Ashwagandha is an adaptogenic herb used traditionally for vitality and male reproductive health. Modern trials have tested standardized extracts for stress, strength, and sexual function. Testosterone effects seem most reliable when subjects are stressed, de-trained but starting resistance training, overweight/aging, or subfertile. Extract composition (root-only vs root+leaf), withanolide content, and dose likely influence outcomes.
Methods Used
Approach
-
Identify standardized extracts with published human data on testosterone: KSM-66 (root-only, full-spectrum), Shoden (root/leaf beadlets with high withanolide glycosides), Sensoril (root+leaf), and whole-root powder.
-
Compare populations, doses, durations, and testosterone outcomes.
-
Synthesize which extract/dose has the most consistent, clinically meaningful effect sizes.
Data Collection
Key trials/data points:
KSM-66 (root-only, 600 mg/day) in young men starting resistance training for 8 weeks increased serum testosterone vs placebo and enhanced strength/muscle gains.
KSM-66 or similar root extract (600 mg/day) in adults and healthy men improved sexual health metrics and showed testosterone increases in multiple 8-week RCTs.
Shoden (21 mg/day withanolide glycosides; older overweight men) in a 16-week double-blind, placebo-controlled crossover trial increased DHEA-S (~18%) and testosterone (~15%) at 8 weeks (attenuation later).
Whole-root powder (5 g/day for 3 months) improved testosterone and LH in infertile men.
Safety: Root extract over 8 weeks shown safe in healthy adults.
Researchers' Summary of Findings
Impact on Health
Athletic/strength settings: KSM-66 appears to support higher testosterone alongside strength and hypertrophy gains during novice training cycles.
Stress/age-related vitality: Shoden increased DHEA-S and testosterone in overweight men 40–70, suggesting utility in stress-linked low-normal androgens.
Male fertility: High-dose whole-root powder improved testosterone, LH, and semen parameters in subfertile men.
General health: Benefits are modest and context-dependent; lifestyle (sleep, training, weight) still exerts larger effects on testosterone than any single supplement.
Health Implications
For men aiming to optimize testosterone:
Best-supported choice: Root-only, full-spectrum extract (KSM-66), ~600 mg/day, 8–12 weeks, especially when combined with resistance training or in high-stress contexts.
Alternative with androgen signal: Shoden (delivering ~21 mg withanolide glycosides/day) showed increases in testosterone and DHEA-S in overweight older men by week 8; effects waned later in crossover.
Fertility-focused: Whole-root powder, 5 g/day for ~12 weeks has supportive data in infertile men under medical supervision.
Caveats: Choose third-party tested products; monitor thyroid/med interactions; use alongside sleep, training, and nutrition, which have larger and safer long-term impacts.
Sustainability
Root-only extracts concentrate traditional plant parts used in Ayurveda and may reduce agricultural load per effective dose compared with high-gram whole-root powders. Choose suppliers with transparent sourcing and quality certifications (e.g., USP/NSF) to minimize adulteration and environmental impact.
DOI
10.1186/s12970-015-0104-9.
