Ashwagandha
Withania somnifera (KSM-66/Sensoril)
Ashwagandha (Withania somnifera) is an adaptogenic herb used in Ayurvedic medicine for thousands of years, standardized in modern supplements to withanolide content (KSM-66 to ≥5% withanolides from root; Sensoril to ≥10% withanolides from root and leaf). It is primarily used to reduce cortisol and perceived stress, improve sleep quality, support testosterone levels in men, and enhance physical endurance and recovery. Clinical trials support its use for anxiety reduction, HPA axis regulation, and modest improvements in strength and body composition.
Mechanism of Action
Ashwagandha's primary bioactive withanolides modulate the hypothalamic-pituitary-adrenal (HPA) axis by attenuating cortisol secretion and reducing the sensitization of stress pathways, with evidence suggesting partial agonism at GABA-A receptors contributing to anxiolytic effects. Withanolides also inhibit NF-κB signaling and reduce pro-inflammatory cytokines (IL-6, TNF-α), while withaferin A has demonstrated inhibition of Hsp90, affecting steroidogenic pathways. Additionally, ashwagandha appears to support luteinizing hormone (LH) signaling and reduce oxidative stress in Leydig cells, which may explain observed increases in testosterone in hypogonadal or stressed males.
Evidence by Health Goal(18 goals)
Dosing Protocols
With meals to minimize gastrointestinal discomfort; evening dosing may enhance sleep benefits
Cycle: 8-12 weeks on, 4 weeks off is commonly recommended, though continuous use up to 6 months has been studied safely
KSM-66 is root-only extract preferred for stress/testosterone applications (600mg/day most studied dose); Sensoril uses root+leaf blend at lower doses (125-250mg twice daily). Higher doses of 600mg/day show stronger cortisol-lowering and performance effects. Standardization to withanolide percentage is essential when selecting a product.
Safety & Side Effects
Ashwagandha has a well-established safety profile at standard doses (300-600mg/day) over periods up to 6 months, with most clinical trials reporting minimal adverse events; however, isolated case reports of hepatotoxicity warrant caution with high-dose or prolonged unsupervised use, and it should be avoided during pregnancy, in autoimmune disorders, and in individuals with thyroid disease without medical supervision.
Possible Side Effects
- !Gastrointestinal discomfort including nausea and loose stools, particularly on an empty stomach
- !Drowsiness or excessive sedation, especially at higher doses or with evening use
- !Thyroid hormone elevation (increased T3/T4) - relevant in those with hyperthyroid conditions
- !Rare hepatotoxicity - isolated case reports of liver injury with long-term high-dose use
- !Headache reported in a minority of users during initial use
- !Potential exacerbation of autoimmune conditions due to immunomodulatory activity
- !Nasal congestion or mild allergic reactions in individuals sensitive to Solanaceae family plants
Interactions
- -May potentiate sedative medications (benzodiazepines, barbiturates, zolpidem) - additive CNS depression risk
- -Can lower blood pressure - use caution with antihypertensive drugs (may cause additive hypotension)
- -May enhance thyroid hormone levels - can interfere with thyroid medication dosing (levothyroxine)
- -Immunostimulatory properties may counteract immunosuppressant drugs (cyclosporine, tacrolimus)
- -Additive cortisol-lowering effect when combined with other adaptogens (rhodiola, phosphatidylserine) - monitor for excessive HPA suppression
Cost & Where to Buy
KSM-66 and Sensoril are licensed branded extracts commanding a price premium over generic ashwagandha; generic root powder is cheaper but withanolide content is variable. Monthly cost at 600mg/day KSM-66 typically falls between $20-$35 from reputable brands. Bulk powder options reduce cost significantly.
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