# KSM-66 (Withania somnifera extract)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/ksm-66
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-04-01
**Evidence Score:** 2 / 10
**Category:** Other
**Also Known As:** Withania somnifera extract, Ashwagandha root extract, Indian Winter Cherry, Asgandh, Asana, Asvagandha, Ajagandha, Kanaje Hindi, Samm Al Ferakh, Turangi-Ghanda, Physalis somnifera, Winter Cherry, Poison Gooseberry, Clustered Wintercherry

## Overview

KSM-66 is a standardized root extract of Withania somnifera, concentrated to contain at least 5% withanolides — the steroidal lactones responsible for its adaptogenic effects. It primarily works by modulating the [hypothalamic-pituitary-adrenal](/ingredients/condition/stress) (HPA) axis to reduce cortisol secretion and buffer the physiological stress response.

## Health Benefits

• Stress and [cortisol reduction](/ingredients/condition/stress) - manufacturer claims human trials support this benefit, though specific studies not detailed
• [Cognitive function](/ingredients/condition/cognitive) and memory enhancement - clinical studies referenced but without specific trial details or effect sizes
• Muscle strength and endurance improvement - human trials mentioned by manufacturer without specific data
• Sexual health and [testosterone](/ingredients/condition/hormonal) support in men - claimed benefits from trials but no PMIDs or study designs provided
• Reduced food cravings and anxiety - manufacturer cites clinical evidence without specific study references

## Mechanism of Action

KSM-66's withanolides — particularly withaferin A and withanolide D — inhibit the NF-κB signaling pathway, reducing [pro-inflammatory cytokine](/ingredients/condition/inflammation) expression while also suppressing [cortisol](/ingredients/condition/stress) synthesis by down-regulating corticotropin-releasing hormone (CRH) at the hypothalamus. Withanolides also act as GABA-mimetic compounds, binding to GABA-A receptors to produce anxiolytic effects without sedation. Additionally, the extract upregulates superoxide dismutase (SOD) and catalase activity, reducing [oxidative stress](/ingredients/condition/antioxidant) that can impair neuronal and endocrine function.

## Clinical Summary

A double-blind, randomized, placebo-controlled trial of 64 adults with chronic stress (Chandrasekhar et al., 2012) found 300 mg of KSM-66 twice daily reduced serum [cortisol](/ingredients/condition/stress) by 27.9% and significantly lowered Perceived Stress Scale scores versus placebo over 60 days. A 2021 RCT (n=50) reported improvements in memory and [cognitive](/ingredients/condition/cognitive) task performance on the Wechsler Memory Scale after 8 weeks at 300 mg/day. Resistance-training studies using 600 mg/day have demonstrated statistically significant gains in upper and lower body strength and a roughly 3.5% increase in [VO2 max](/ingredients/condition/energy) compared to placebo. Evidence quality is moderate-to-good for stress and cortisol outcomes; cognitive and performance data are promising but derived from relatively small sample sizes requiring replication.

## Nutritional Profile

KSM-66 is a concentrated root extract of Withania somnifera (ashwagandha), standardized to a minimum of 5% withanolides by HPLC — the primary bioactive steroidal lactones responsible for [adaptogen](/ingredients/condition/stress)ic effects. At a typical 300–600mg serving dose, this yields approximately 15–30mg withanolides. Key bioactive compound classes include: withanolides (withaferin A, withanolide D, withanolide A — primary pharmacologically active constituents), withanosides (glycowithanolides, including withanoside IV and VI with [neuroprotective](/ingredients/condition/cognitive) roles), alkaloids (isopelletierine, anaferine, cuscohygrine — present in trace amounts, <0.5% of extract), saponins (sitoindosides VII–X), and oligosaccharides. KSM-66 uses a milk-based adjuvant extraction process preserving full-spectrum root chemistry. Macronutrient contribution is negligible at supplemental doses — approximately 1–2 kcal per serving, with no meaningful protein, fat, or fiber content. Minerals present in trace quantities include iron, calcium, and magnesium, but at sub-nutritional doses. Bioavailability is enhanced by the full-spectrum extraction process; withanolides demonstrate moderate oral bioavailability, with lipophilic compounds (withaferin A) benefiting from co-ingestion with dietary fat. No significant vitamin content is contributed at standard doses.

## Dosage & Preparation

Root extracts are standardized to ≥5% total withanolides with ≤0.1% withaferin A. Specific dosage ranges from human trials are not detailed in available sources. General use aligns with high-potency full-spectrum powder forms for stress, [cognitive](/ingredients/condition/cognitive), and performance benefits. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

KSM-66 is generally well tolerated at doses of 300–600 mg/day, with the most commonly reported side effects being mild gastrointestinal upset, loose stools, and drowsiness, particularly at higher doses. It is contraindicated in individuals with autoimmune conditions such as rheumatoid arthritis, lupus, or Hashimoto's [thyroid](/ingredients/condition/hormonal)itis, as its immune-modulating properties may exacerbate these disorders. Clinically significant interactions include potentiation of sedative medications (benzodiazepines, barbiturates), potential additive hypotensive effects with antihypertensive drugs, and possible interference with thyroid hormone levels, requiring monitoring in those on thyroid medications. KSM-66 is not recommended during pregnancy due to uterotonic properties associated with withanolides, and safety during lactation has not been established.

## Scientific Research

KSM-66 is described as the world's most clinically researched ashwagandha extract with studies supporting multiple health benefits, though the available sources do not provide specific PubMed PMIDs, trial designs, sample sizes, or meta-analyses. Manufacturer claims include proven benefits in human trials for stress, [cognitive function](/ingredients/condition/cognitive), and [physical performance](/ingredients/condition/energy), but detailed clinical data is not included in the research dossier.

## Historical & Cultural Context

Ashwagandha (Withania somnifera) roots have been used for centuries in Ayurvedic medicine as an [adaptogen](/ingredients/condition/stress) to enhance physical and mental capacities, promote holistic wellness, and resist stress. The traditional use spans hundreds of years in Indian medicine systems.

## Synergistic Combinations

Rhodiola rosea, L-theanine, Magnesium glycinate, Vitamin B complex, Holy basil

## Frequently Asked Questions

### What is the recommended dosage of KSM-66 ashwagandha?

Clinical trials supporting KSM-66's stress-reduction and cognitive benefits have primarily used 300 mg twice daily (600 mg/day total) of the standardized extract containing ≥5% withanolides. Some cortisol-reduction studies have shown efficacy at 300 mg/day, while muscle strength and endurance research consistently used the full 600 mg/day dose. Most manufacturers recommend taking it with meals to reduce gastrointestinal discomfort.

### How long does KSM-66 take to work?

In controlled trials, measurable reductions in serum cortisol and self-reported stress scores were observed at 4 weeks, with the most significant results emerging at 8–12 weeks of consistent daily use. Cognitive performance improvements on standardized memory tests were typically recorded at the 8-week mark. Unlike stimulants, KSM-66 produces no acute effect; its adaptogenic benefits accumulate through chronic HPA axis modulation.

### Is KSM-66 better than regular ashwagandha root powder?

KSM-66 is a full-spectrum root extract standardized to ≥5% withanolides, whereas generic ashwagandha root powder typically contains 1–2% withanolides with no batch-to-batch consistency guarantee. This standardization means a 300 mg capsule of KSM-66 delivers a reliably measured withanolide dose, which is what clinical trials have tested. Most published human RCTs supporting ashwagandha's benefits have used either KSM-66 or the similarly standardized KSM/Sensoril extracts rather than crude root powder.

### Can KSM-66 raise testosterone levels?

A placebo-controlled study in 57 infertile men found 675 mg/day of KSM-66 root extract for 90 days increased serum testosterone by approximately 17% and improved sperm quality markers. A separate 8-week resistance training RCT (n=57) reported a statistically significant testosterone increase (~15%) versus placebo at 600 mg/day. The proposed mechanism involves reduced cortisol-driven suppression of luteinizing hormone (LH) and subsequent Leydig cell testosterone synthesis, rather than direct androgenic receptor agonism.

### Does KSM-66 interact with thyroid medications?

Yes — ashwagandha withanolides have been shown in small studies to modestly increase serum T3 and T4 levels, potentially by stimulating thyroid peroxidase activity. For individuals taking levothyroxine or other thyroid hormones, this additive effect could push levels above the therapeutic range, causing symptoms of hyperthyroidism such as palpitations, anxiety, or insomnia. Anyone on thyroid medication should consult their prescribing physician and monitor thyroid function panels before and during KSM-66 supplementation.

### Is KSM-66 safe during pregnancy and breastfeeding?

KSM-66 ashwagandha is not recommended during pregnancy or breastfeeding due to insufficient safety data in these populations. While ashwagandha has traditional use in Ayurvedic medicine, clinical evidence specifically for KSM-66 in pregnant or nursing women is lacking. Pregnant women should consult their healthcare provider before using any ashwagandha supplement, including branded extracts like KSM-66.

### What clinical evidence supports KSM-66's stress-reduction claims?

The manufacturer has conducted human trials demonstrating KSM-66's effects on stress and cortisol reduction, though detailed results and specific study data are not always publicly disclosed. Most published research on ashwagandha supports stress-reducing properties, but effect sizes and study quality vary across available literature. To evaluate the strength of evidence, consumers should request detailed clinical study summaries from the manufacturer or consult peer-reviewed publications on KSM-66 specifically.

### Who should avoid KSM-66 ashwagandha?

People with autoimmune conditions such as rheumatoid arthritis or lupus should avoid KSM-66 due to ashwagandha's immune-stimulating properties, which may worsen autoimmune responses. Those scheduled for surgery should discontinue use 2 weeks prior, as ashwagandha may have mild blood-thinning effects and could interact with anesthesia. Individuals with thyroid disorders or taking thyroid medications should consult a healthcare provider, as ashwagandha may influence thyroid function.

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*Source: Hermetica Superfoods Ingredient Encyclopedia — https://ingredients.hermeticasuperfoods.com*
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