What is ashwagandha?
Ashwagandha (Withania somnifera) is a root extract classified as an adaptogen — a compound that helps the body adapt to physical and psychological stress. The active compounds are withanolides, which are measured as a percentage on supplement labels. KSM-66 and Sensoril are the two most researched standardised extracts.
How it works
Ashwagandha modulates the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the body's stress response. It reduces serum cortisol levels, the primary stress hormone, and influences GABAergic signalling which contributes to its anxiolytic effects. It also appears to support testosterone production in men under chronic stress.
What the research says
- 300mg of KSM-66 twice daily significantly reduced cortisol levels and perceived stress scores compared to placebo (Chandrasekhar et al., 2012)
- Improved VO2 max and time to exhaustion in elite cyclists (Sansone et al., 2018)
- Increased testosterone and luteinising hormone in men with stress-related infertility (Mahdi et al., 2011)
- Improved sleep quality and sleep onset latency at 300mg twice daily (Langade et al., 2019)
Effective dose
300–600mg daily of a standardised extract (KSM-66 or Sensoril). Split into two doses with meals. Effects accumulate over 4–8 weeks of consistent use — not an acute performance supplement. Look for extracts standardised to at least 5% withanolides.
What to check on the label
Confirm the extract type (KSM-66 or Sensoril) and withanolide percentage. Generic "ashwagandha root powder" without standardisation is significantly less potent and not equivalent to the doses used in research. Many products underdose at 100–200mg — below the threshold shown to produce meaningful effects.
Safety
Well tolerated in healthy adults at recommended doses. Avoid during pregnancy. May interact with thyroid medications — consult a doctor if taking thyroid treatment. Rare cases of liver injury reported at very high doses.