When a clinician or researcher recommends ashwagandha, a practical question follows: which extract? KSM-66 and Sensoril are branded preparations used in human trials, but they differ in plant parts, extraction specifications, trial doses, and study populations. No randomized head-to-head trial comparing them was identified. The defensible approach is to match the exact preparation to the outcome studied rather than treating every milligram of ashwagandha extract as equivalent.

Manufacturing Origins and Phytochemical Differences

Withania somnifera (L.) Dunal, family Solanaceae, contains steroidal lactones called withanolides, alkaloids, and other constituents. Root and leaf have different chemical profiles, and the clinical activity of a finished extract cannot be assigned confidently to one isolated withanolide. Laboratory findings about compounds such as withaferin A are not, by themselves, proof of the benefits or risks of a human supplement.

KSM-66 is a root-only extract developed by Ixoreal Biomed. The 2012 stress trial describes the tested material as a full-spectrum root extract containing at least 5% withanolides by HPLC and made without alcohol or synthetic solvents.

Sensoril is an aqueous extract made from both roots and leaves. This botanical distinction matters. A 125 mg Sensoril capsule and a 300 mg KSM-66 capsule are not equivalent quantities of the same extract, and commercial percentages may use different analytical definitions. Extract weight alone therefore cannot establish greater potency or “dose efficiency.”

Ayurvedic Pharmacopoeial and Indian Regulatory Context

The Ayurvedic Pharmacopoeia of India identifies Ashvagandha as the dried mature root of Withania somnifera. A 2021 Ministry of Ayush advisory stated that the root is used in classical Ayurveda, Siddha, and Unani formulations and that leaves were not reported for use in the cited classical ASU texts. In April 2026, the Ministry directed Ayush manufacturers to use only Ashwagandha roots and prohibited leaves in Ayush products; FSSAI also clarified that only roots and their extracts are permitted in the food-product categories covered by its advisory. KSM-66’s root-only identity therefore aligns with the current Indian pharmacopoeial and regulatory plant-part standard, whereas Sensoril’s root-and-leaf composition does not. This establishes classical and regulatory alignment, not universal clinical superiority or proof that every root-and-leaf product sold elsewhere is unsafe.

Stress, Cortisol, and Anxiety: Evidence Comparison

KSM-66 was tested in a 60-day randomized, double-blind, placebo-controlled trial in 64 adults with chronic stress. Participants received 300 mg twice daily or placebo. The extract group improved on the Perceived Stress Scale and other questionnaires, and mean serum cortisol fell 27.9% from baseline, compared with 7.9% in the placebo group. Adverse effects were mild and comparable, with no serious events.

A peer-reviewed 2024 randomized trial enrolled 131 chronically stressed adults and included 98 in the final per-protocol analysis. Participants received 125, 250, or 500 mg/day of aqueous Sensoril root-and-leaf extract, or placebo, for eight weeks. All three doses improved perceived stress and Hamilton anxiety and depression scores relative to placebo and lowered plasma cortisol, ACTH, and salivary alpha-amylase at week eight.

Both preparations therefore have short-term stress data, but the trials differed in design, participants, dose arms, assays, and analysis. They cannot be used as a numerical contest. Changes in cortisol and ACTH are compatible with an effect on stress physiology, but the branded human trials do not prove the specific HSP70–glucocorticoid-receptor mechanism.

Sleep Quality Evidence

KSM-66 has a dedicated trial in 80 adults, half with insomnia and half without. Participants received 300 mg twice daily for eight weeks. In the insomnia subgroup, the extract improved sleep quality, sleep-onset latency, mental alertness on rising, and anxiety measures compared with placebo. Participants without insomnia also reported better sleep, but not the same anxiety or morning-alertness benefits.

The often-cited 150-person study was not a KSM-66 trial; it tested 120 mg/day of Shoden, a different root-and-leaf extract, for six weeks. Sensoril has supportive sleep findings in its 2024 stress trial, where sleep was a secondary outcome and PSQI and visual-analogue sleep scores improved at week eight. Between these two brands, KSM-66 has the more directly applicable sleep-specific trial.

Athletic Performance and Muscle Strength

A KSM-66 trial enrolled 57 young men with little resistance-training experience. During eight weeks of training, participants received 300 mg twice daily or placebo. The extract group had greater gains in bench-press and leg-extension strength, selected muscle-size measures and testosterone, a greater reduction in body-fat percentage, and a smaller exercise-related rise in creatine kinase. The findings are promising but come from a small male sample trained under a structured program.

A separate 12-week trial in 50 healthy athletic adults found a greater increase in maximal oxygen uptake with KSM-66 than placebo. Sensoril was tested in the 12-week STAR trial, which randomized 38 recreationally active men to 500 mg/day or placebo during resistance training. Sensoril produced greater gains in squat and bench-press one-repetition maximum and a more favorable android-to-gynoid fat-ratio change. Most other body-composition, recovery, and hemodynamic measures did not differ between groups.

KSM-66 vs. Sensoril: Clinical Evidence Summary

The comparison is outcome-specific. Both extracts have randomized trials, but most studies are small and short, and several involved manufacturer support. Differences between separate trials are not evidence of direct superiority.

Outcome domain KSM-66 evidence Sensoril evidence Evidence-based reading
Stress and cortisol 64-person RCT; 600 mg/day for 60 days 131 enrolled, 98 analyzed; 125–500 mg/day for 8 weeks Both supported; no head-to-head winner
Anxiety symptoms Validated symptom-scale improvements in the stress trial HAM-A improvement across tested doses in the 2024 trial Supportive, not directly comparable
Sleep Dedicated 80-person trial at 600 mg/day for 8 weeks Secondary sleep outcomes in a stress trial KSM-66 has the more direct brand-specific study
Strength and endurance 57-man resistance-training RCT and separate VO2max RCT 38-man STAR resistance-training RCT at 500 mg/day Both have data; KSM-66 covers more distinct endpoints
Cognitive function 50-person pilot RCT in mild cognitive impairment at 600 mg/day No equivalent Sensoril MCI trial cited here No direct brand comparison
Trial dose Often 600 mg/day in the cited trials 125–500 mg/day in the cited trials Milligrams are not potency-equivalent
KSM-66 vs. SENSORIL: VERIFIED DIFFERENCES
KSM-66
Sensoril
Root-only extract
Root-and-leaf aqueous extract
At least 5% withanolides in the cited stress trial
Different proprietary standardization; percentages are not directly comparable
600 mg/day in many cited RCTs
125–500 mg/day in cited RCTs
Plant part aligns with API and current Indian Ayush direction
Leaf inclusion does not align with current Indian root-only direction

No randomized head-to-head trial was identified. Match the exact extract, dose, population, outcome, product quality, and individual safety considerations.

Safety Profile and Practical Choice

Short trials generally describe both extracts as well tolerated, but small RCTs cannot exclude rare harms. The KSM-66 stress trial reported mild adverse effects comparable to placebo and no serious events. The 2024 Sensoril trial reported no serious events; minor complaints occurred across treatment and placebo groups without an obvious pattern. These observations apply only to the tested products, doses, and durations.

NIH’s Office of Dietary Supplements states that ashwagandha appears reasonably well tolerated for about three months, while long-term safety is uncertain. Reported effects include stomach upset, loose stools, nausea, and drowsiness. Rare liver injuries have been reported, but case reports do not establish withaferin A as the specific cause. Ashwagandha may affect thyroid function and interact with thyroid hormone, diabetes medicines, antihypertensives, immunosuppressants, and sedatives. Pregnancy, breastfeeding, liver or thyroid disease, endocrine disorders, autoimmune illness, and concurrent medication require professional review.

The evidence-based conclusion is narrower than the marketing version. KSM-66 offers root-only pharmacopoeial alignment and direct trials for stress, sleep, strength, cardiorespiratory endurance, and mild cognitive impairment. Sensoril has randomized evidence for stress at 125–500 mg/day, secondary sleep outcomes, and a small strength-training trial at 500 mg/day. Neither should be chosen solely because one label lists a higher percentage or lower dose. Consult a qualified Ayurvedic practitioner and a healthcare provider before use, especially during pregnancy or breastfeeding, with liver or thyroid disease, or when taking prescription medicines.

References

  1. NIH Office of Dietary Supplements
  2. 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 (2012), PubMed Central
  3. Mdpi (mdpi.com)
  4. Ministry of AYUSH
  5. Fssai (fssai.gov.in)
  6. Systemic type Epstein-Barr virus-related lymphoproliferative diseases in children and young adults: challenges for pediatric hemato-oncologists and infectious disease specialists (2007), PubMed
  7. Clinical evaluation of the pharmacological impact of ashwagandha root extract on sleep in healthy volunteers and insomnia patients: A double-blind, randomized, parallel-group, placebo-controlled study (2021), PubMed
  8. Global Epidemiology of Ischemic Heart Disease: Results from the Global Burden of Disease Study (2020), PubMed
  9. Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial (2015), PubMed
  10. Efficacy of Ashwagandha (Withania somnifera [L.] Dunal) in improving cardiorespiratory endurance in healthy athletic adults (2015), PubMed
  11. Effects of an Aqueous Extract of Withania somnifera on Strength Training Adaptations and Recovery: The STAR Trial (2018), PubMed
  12. Efficacy and Safety of Ashwagandha (Withania somnifera (L.) Dunal) Root Extract in Improving Memory and Cognitive Functions (2017), PubMed