Ashwagandha, ranked by what the evidence actually supports.
Ashwagandha is the most-studied adaptogen on Earth — over 30 RCTs and counting. The KSM-66 extract alone has 14+ published trials. But the extract type matters far more than the dose: generic root powder with unstandardised withanolide content has no clinical evidence behind it. This page ranks 10 popular ashwagandha products on extract quality and RCT evidence.
Last updated: August 23, 2026 · Sources: Chandrasekhar 2012, Wankhede 2015, Langade 2019, Bonilla 2021 meta-analysis
At a glance
Best evidence per dollar
NOW Foods Ashwagandha KSM-66
90 caps at 450 mg/cap = $19.95 on iHerb. Same branded KSM-66 extract as the published RCTs at ~40% lower cost than Thorne.
Best practitioner-grade
Thorne Ashwagandha KSM-66 450 mg
NSF Certified for Sport. The exact extract used in Chandrasekhar 2012 + Langade 2019 RCTs. $32 USD on iHerb.
Best for sleep
Pure Encapsulations Sensoril
Root+leaf extract at 10% withanolides. More sedating than KSM-66 per Auddy 2008. Best for sleep-specific goals.
Product comparison
Compare 10 popular ashwagandha products on extract type, withanolide %, dose per capsule, RCT evidence, and price per dose. Evidence 5/5 = multiple published RCTs on this exact branded extract.
Evidence 1/5 = no published RCTs on this SKU, 5/5 = multiple RCTs on the branded extract. "Generic root powder" products have unstandardised withanolide content and the published RCTs DO NOT apply to them — even if the dose looks similar on the label.
Root + leaf extract standardised to 10% withanolides. Made by Natreon (USA/India). Includes leaf alkaloids that make it more sedating than KSM-66. Used in Auddy 2008 (chronic stress) and Salve 2019 (sleep + anxiety). Less evidence for athletic performance than KSM-66.
Best for: sleep-specific goals. More sedating than KSM-66 — better for nighttime use.
High-concentration beadlet form made by Arjuna Natural (India). Smaller evidence base than KSM-66 or Sensoril — primarily sleep + stress RCTs. The higher withanolide % means a lower total dose per serving (60-120 mg/day vs 300-600 for KSM-66). Best if you want minimum pills/capsules.
Best for: people who want fewer pills per dose. Sleep-specific goals.
Dried and powdered root without standardised withanolide content. Marketed as "traditional" or "whole root". Withanolide content varies 3-10x between batches and harvests. The clinical-trial evidence DOES NOT apply to these products — generic products have not been tested at the doses you are taking.
Best for: no one. Cheap, but no demonstrated efficacy.
How much ashwagandha do you actually need?
The dose depends on which extract you choose. KSM-66 RCTs use 300-600 mg/day. Sensoril uses 125-250 mg/day.
Extract
Standard dose
Withanolides
KSM-66
300-600 mg/day
15-30 mg
Sensoril
125-250 mg/day
12-25 mg
Shoden
60-120 mg/day
21-42 mg
Generic root powder
1-3 g/day
Variable
Sources: Chandrasekhar 2012 (KSM-66 at 300 mg BID), Langade 2019 (KSM-66 at 300 mg BID), Auddy 2008 (Sensoril at 125 mg BID). Take with food to enhance absorption.
Top picks by use case
Best evidence per dollar
NOW Foods Ashwagandha KSM-66
90 caps at 450 mg/cap = $19.95 on iHerb. Same branded KSM-66 extract as Thorne at ~40% lower cost. 3-month supply at 1 cap/day.
Best practitioner-grade
Thorne Ashwagandha KSM-66
NSF Certified for Sport. The exact extract used in Chandrasekhar 2012 + Langade 2019. $32 USD on iHerb. Best for athletes and quality-conscious buyers.
Best for sleep
Pure Encapsulations Sensoril
Root+leaf extract at 10% withanolides. More sedating than KSM-66. The form to choose when sleep is your primary goal and stress is secondary.
Best AU mass-market
Blackmores Ashwagandha+
$24.95 at Chemist Warehouse. Reformulated to KSM-66 standardised at 300 mg/day — matches Chandrasekhar 2012 stress protocol. Available at Watsons/Boots TH.
Best athletic performance
NOW Foods KSM-66 (high-dose)
Wankhede 2015 used 600 mg/day KSM-66 for 8 weeks of resistance training. Two 450 mg caps = 900 mg/day slightly above the tested dose. Use 1 cap + 1 150 mg split = 600 mg.
Best budget
Herbs of Gold Ashwagandha
120 caps at 500 mg/cap = $34.95 at Chemist Warehouse. Generic root powder — NOT the same as KSM-66. Reasonable cheap option if you accept lower evidence base.
Side effects & the thyroid caveat
Ashwagandha is generally well-tolerated. Side effects in 5-10% of users (mild GI upset, drowsiness, headache). Two important safety considerations:
Common (expected) side effects
Mild GI upset (especially on empty stomach)
Drowsiness (more common with Sensoril)
Headache (dose-related, usually resolves)
Loose stools in 5-10%
Vivid dreams (rare)
Important contraindications
Hyperthyroidism — ashwagandha raises T3/T4 (Sharma 2018). Avoid if Graves' disease or hyperthyroid phase of Hashimoto's.
Autoimmune conditions — immunomodulating; may worsen lupus, RA
Sedative medications — additive CNS depression
Levothyroxine — may overstimulate thyroid; monitor TSH
Most users notice benefits in 2-4 weeks. The Chandrasekhar 2012 trial measured significant differences at 8 weeks. Athletic performance gains typically appear at 8-12 weeks. Allow at least 8 weeks of consistent use before evaluating.
References & sources
NIH Office of Dietary Supplements — Ashwagandha Fact Sheet. ods.od.nih.gov
Chandrasekhar K, et al. (2012). A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults. Indian Journal of Psychological Medicine 34(3):255-262. PMID: 23439798
Langade D, et al. (2019). Efficacy and Safety of Ashwagandha (Withania somnifera) Root Extract in Sleep and Anxiety Effects. Cureus 11(9):e5797. PMID: 32021735
Wankhede S, et al. (2015). Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial. Journal of the International Society of Sports Nutrition 12:43. PMID: 26609282
Bonilla DA, et al. (2021). Effects of Ashwagandha (Withania somnifera) on Physical Performance: Systematic Review and Bayesian Meta-Analysis. PLOS One 16(4):e0250784.
Lopresti AL, et al. (2019). An investigation into the stress-relieving and pharmacological actions of an ashwagandha extract: A randomized, double-blind, placebo-controlled study. Medicine 98(37):e17186. PMID: 31517876
Sharma AK, et al. (2018). Efficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients. JACM 24(3):243-248. PMID: 28829155
Examine.com — Ashwagandha research review. examine.com
Chemist Warehouse AU, iHerb, Amazon, Swisse AU, Blackmores AU, BioCeuticals AU, Ethical Nutrients, Herbs of Gold, Nature's Own, Thorne, Pure Encapsulations, NOW Foods, Nootropics Depot — product pages and price snapshots cited per row above (date column).
Trusted brands we rate
These 10 brands are featured on every vitfacts.com comparison page. We track them
for ingredient transparency, third-party testing, and Thailand availability.
A heritage naturopathic brand spanning over 90 years, known for rigorous ingredient sourcing and massive pharmacy presence throughout the Asia-Pacific region.
A premium, practitioner-only brand (owned by Blackmores) offering highly concentrated, clinical-strength formulas that are frequently recommended by healthcare professionals.
A high-quality pharmacy brand heavily focused on evidence-based ingredients, widely known for its "Inner Health" probiotic range and highly absorbable magnesium powders.
Born in Australia, this brand formulates therapeutic herbal and nutritional supplements with a strict focus on purity, offering many vegan-friendly options.
One of Australia's longest-running and most accessible vitamin brands, providing a massive, budget-friendly range found in most major supermarkets and pharmacies.
While based in the US, Thorne is heavily imported and highly sought after by functional medicine practitioners globally—including in both Australia and Thailand. It is considered a gold standard due to its strict four-round testing protocol and complete absence of unnecessary fillers or binders.
An Australian-made value brand founded in 2006, sold through Chemist Warehouse and major AU pharmacies. Part of the Nature's Care family (est. 1990), offering a wide mass-market supplement range covering fish oil, vitamins C/D, magnesium, probiotics, zinc, iron, ashwagandha, collagen, and CoQ10.
Why these 10? See the VitFacts editorial policy page (forthcoming) for the criteria — minimum
10 years of documented safety record, public certificate-of-analysis policy, and verifiable
Thailand distribution.
