HPC › Nutrition › Glossary
Ashwagandha (Withania somnifera) is an adaptogenic root extract used in Ayurvedic medicine for its capacity to modulate the hypothalamic-pituitary-adrenal axis, blunting the cortisol stress response. Its primary bioactive compounds, withanolides, bind to glucocorticoid receptors and interact with GABAergic pathways. Clinical trials consistently show reduced morning cortisol in chronically stressed adults taking standardised extracts.
Most clinical evidence is for proprietary standardised extracts such as KSM-66 and Shoden at 240 to 600 mg daily; raw root powder is not equivalent in dose or efficacy.
How it works
Ashwagandha's principal bioactive compounds are withanolides, a class of steroidal lactones concentrated in the root. Withanolides modulate glucocorticoid receptor activity and blunt the hypothalamic-pituitary-adrenal axis response to psychological stressors, reducing downstream cortisol secretion 23. The mechanism resembles that of a dimmer switch on the stress-signalling circuit: rather than blocking cortisol release entirely, withanolides attenuate the amplitude of the HPA response, so morning cortisol readings fall measurably but the axis retains the capacity to mount a stress response when genuine threat demands it.
GABAergic signalling is also implicated. Withanolides and their metabolites show affinity for GABA-A receptors, which may partly explain the anxiolytic effects recorded in randomised controlled trials independently of the cortisol reduction 2. A 2023 systematic review of nine RCTs found that 250 to 600 mg of standardised W. somnifera extract daily for 30 to 112 days produced statistically significant reductions in morning cortisol across adults with elevated baseline stress levels 3. The review noted large heterogeneity in extract formulations and standardisation levels, meaning the specific extract used matters more than a simple milligram figure.
Beyond cortisol, Lopresti et al. observed that HPA axis attenuation in men was accompanied by increased testosterone production, suggesting withanolides may also modulate the hypothalamic-pituitary-gonadal axis 2. This finding remains preliminary, confined to a single RCT in men with elevated stress, but it is mechanistically coherent: chronic cortisol elevation suppresses gonadotropin-releasing hormone, so reducing cortisol load can permit testosterone recovery without any direct androgenic effect.
Example
A professional experiencing sustained high workload, disrupted sleep, and elevated morning anxiety consults a clinician about stress management options. The clinician recommends a 60-day trial of standardised ashwagandha extract at 300 mg twice daily. By week eight, the individual's morning cortisol has fallen and self-reported anxiety scores have improved, the outcome consistent with the dose and duration used in published randomised trials.
The scenario illustrates that standardised extract at a clinically tested dose and duration, not raw powder taken ad hoc, is what the evidence actually supports.
Why it matters
The HPA axis sits upstream of nearly every physiological stress response: elevated cortisol suppresses testosterone, impairs working memory consolidation during sleep, promotes visceral fat accumulation, and raises cardiovascular inflammatory markers. For anyone whose performance depends on sustained cognitive output, hormonal balance, or recovery capacity, chronically elevated cortisol is not a background condition to manage later. A supplement with replicated, statistically significant evidence of cortisol reduction at doses below 600 mg daily is a meaningful lever in the stress-management toolkit, particularly when behavioural interventions alone prove insufficient 13.
The safety picture is not uniformly reassuring. A case series identified confirmed cases of ashwagandha-induced hepatotoxicity, including fatalities in patients with pre-existing chronic liver disease; cholestatic hepatitis was the most common presentation, typically appearing after four to eight weeks of use 4. The incidence appears rare relative to the scale of consumption, but rare does not mean negligible when the endpoint includes liver failure. Anyone with pre-existing hepatic disease, elevated liver enzymes, or co-administering hepatotoxic drugs should avoid supplementation until clearer safety data exist.
What is ashwagandha and what is it used for?+
Ashwagandha (Withania somnifera) is an adaptogenic root from Ayurvedic medicine used primarily to reduce chronic stress and anxiety. Clinical trials show it lowers morning cortisol concentrations and self-reported stress scores in adults with elevated baseline stress, at standardised extract doses of 240 to 600 mg daily {{cite:10.3390/nu15245015}}{{cite:10.4103/0253-7176.106022}}.
Does ashwagandha actually lower cortisol?+
Yes, within a specific context. A double-blind RCT (n=64, 60 days) recorded a 27.9% reduction in serum cortisol versus placebo in chronically stressed adults taking 300 mg of standardised extract twice daily {{cite:10.4103/0253-7176.106022}}. A 2023 systematic review of nine RCTs replicated the direction of effect across different extract formulations {{cite:10.3390/nu15245015}}.
Is ashwagandha safe? What are the side effects?+
For most adults at studied doses, tolerability is good. A case series documented rare but serious hepatotoxicity, including fatalities in patients with pre-existing liver disease; cholestatic hepatitis was the most common presentation {{cite:10.1097/hc9.0000000000000270}}. Anyone with liver disease, elevated liver enzymes, or concurrent use of hepatotoxic drugs should avoid it until clearer safety data exist.
What dose of ashwagandha is effective for stress?+
Clinical evidence supports 240 to 600 mg daily of a standardised root extract for 60 to 112 days {{cite:10.1097/md.0000000000017186}}{{cite:10.3390/nu15245015}}. The effective dose varies by formulation: 240 mg per day of Shoden and 600 mg per day of KSM-66 both show significant cortisol reduction in published trials. Raw root powder lacks equivalent dosing data.
