Ashwagandha & Longevity: How KSM-66 Withanolides Reduce Cortisol, Protect Nerves, and Slow Biological Aging

Of all the adaptogens studied in longevity medicine, ashwagandha (Withania somnifera) has the most rigorous randomized controlled trial evidence — and the most mechanistically interesting biology. Its active withanolide compounds are steroidal lactones structurally analogous to mammalian steroids, and they exert effects on stress physiology, thyroid function, testosterone signaling, and neurotrophin production that no other plant extract replicates at the level of specificity now documented in human trials.

The longevity case for ashwagandha rests on four pillars: (1) cortisol normalization — chronic cortisol elevation is an independent predictor of accelerated telomere shortening, hippocampal atrophy, and immune senescence; (2) thyroid hormone optimization — ashwagandha increases T3 and T4 in subclinical hypothyroid patients, relevant because thyroid hormone is required for peripheral nerve myelination and regeneration; (3) testosterone restoration in aging men — relevant to Leydig cell function, muscle mass, and anabolic nerve support; and (4) direct neurotrophic signaling through withanolide A’s documented NGF-mimetic receptor activation.

For patients with peripheral neuropathy — a population I see daily at Balance Foot & Ankle in Howell and Bloomfield Hills — ashwagandha is relevant not merely as a stress-reduction supplement but as a targeted nerve-protection agent with three molecular mechanisms that address aspects of neuropathy pathophysiology completely unaddressed by vitamins, minerals, or mitochondrial supplements.

KSM-66: The Ashwagandha Extract With the Strongest Human RCT Evidence

Not all ashwagandha supplements are equivalent. The bioactive compounds are withanolides — a family of steroidal lactone triterpenoids including withaferin A, withanolide A, withanolide D, withanoside IV, and withanoside VI. The concentration and ratio of these compounds varies dramatically depending on extraction method, plant part used, and geographical source. Clinical trials demonstrating efficacy have almost exclusively used two standardized extracts: KSM-66 (Ixoreal Biomed, standardized to ≥5% withanolides, root-only aqueous-alcoholic extraction) and Sensoril (Natreon, standardized to ≥10% withanolides + ≥32% oligosaccharides, mixed root/leaf extraction).

KSM-66 has been used in the majority of high-quality human RCTs published since 2012, including the landmark Choudhary cortisol/cognitive trial, the Wankhede testosterone/muscle trial, and the Chandrasekhar anxiety/IBS trial. Its root-only extraction avoids leaf-specific withanolides (including withaferin A at higher leaf concentrations) that have demonstrated cytotoxicity in some in vitro models at supraphysiological doses. For longevity supplementation with emphasis on tolerability and a 12+ month time horizon, KSM-66 is the appropriate choice.

The Choudhary 2017 RCT: Landmark Evidence for Cortisol Reduction and Cognitive Enhancement

The Choudhary et al. 2017 study, published in the Journal of Dietary Supplements (14(6):599–612), is the most comprehensive human RCT of ashwagandha’s cognitive and stress-reduction effects to date. Sixty-four adults with self-reported cognitive complaints (but without dementia diagnosis) were randomized to KSM-66 300 mg twice daily (600 mg/day total) or placebo for 60 days. Endpoints included the Perceived Stress Scale (PSS), serum cortisol, and a comprehensive neuropsychological battery including immediate/general memory, executive function, sustained attention, and information processing speed.

Stress and cortisol outcomes: PSS scores decreased by 22.1% in the KSM-66 group versus 4.6% in placebo (p < 0.001). Serum cortisol — measured by ELISA in morning fasting samples — decreased by 27.9% in the KSM-66 group versus 7.9% in placebo (p = 0.006). This is one of the largest cortisol reductions documented with any non-pharmacological intervention in a controlled setting.

Cognitive outcomes: The KSM-66 group showed statistically significant improvements in immediate memory (Wechsler Memory Scale), general memory, executive function (Trail Making Test B), sustained attention (Digit Vigilance Test), and information processing speed. Effect sizes were moderate to large (Cohen’s d 0.51–0.89). The cognitive benefits were strongly correlated with cortisol reduction — suggesting that HPA axis normalization is a primary (though not exclusive) driver of the cognitive improvements.

Safety: No clinically significant adverse events in either group. Thyroid function tests were not significantly altered at 600 mg/day KSM-66 in this population, though higher doses and longer durations have shown mild T3/T4 increases in subclinical hypothyroid adults (Sharma 2018, J Altern Complement Med).

Longevity Biology: Why Cortisol Normalization Is a Master Aging Lever

Chronic cortisol elevation — whether from psychological stress, sleep deprivation, metabolic syndrome, or HPA axis dysregulation in aging — drives accelerated biological aging through at least five parallel mechanisms, each independently documented in human longitudinal studies.

Telomere Attrition

Cortisol reduces telomerase activity in lymphocytes by suppressing hTERT (human telomerase reverse transcriptase) gene transcription via glucocorticoid response elements in the hTERT promoter. The Epel et al. 2004 landmark study (PNAS) demonstrated that perceived stress — correlated with elevated cortisol — predicted shorter leukocyte telomere length with an effect equivalent to 9–17 additional years of biological aging. Ashwagandha’s 27.9% cortisol reduction in the Choudhary trial is mechanistically positioned to slow this cortisol-driven telomere attrition.

Hippocampal Atrophy and Memory Impairment

Glucocorticoid receptor (GR) activation in hippocampal neurons reduces BDNF expression via GR-mediated suppression of the BDNF promoter IV CRE element. Sustained cortisol elevation — even within the “normal” range — reduces hippocampal volume by 0.5–1% per year in middle-aged adults, accelerating the hippocampal atrophy rate that normally occurs at approximately 0.5–1% per decade before age 50. Ashwagandha’s cortisol reduction and its independent withanolide-A NGF-mimetic activity (documented in PC12 cells — Tohda 2005, Br J Pharmacol) both support hippocampal volume maintenance through complementary mechanisms.

Immune Senescence and NK Cell Decline

Cortisol suppresses NK cell cytotoxicity via GR-mediated reduction of perforin and granzyme B gene expression — a clinically significant immunosuppression that increases cancer surveillance failure risk in chronically stressed aging adults. The Pratte et al. 2014 meta-analysis (8 RCTs of ashwagandha) found significant immune-stimulating effects including increased NK cell activity and reduced CRP — consistent with HPA axis normalization restoring cortisol-suppressed immune surveillance.

Muscle Catabolism and Sarcopenia

Cortisol activates FOXO1 and FOXO3a in skeletal muscle, transcribing MuRF-1 (muscle RING-finger protein 1) and MAFbx (muscle atrophy F-box) — the E3 ubiquitin ligases that drive myofibrillar protein degradation. Chronic cortisol elevation is a primary driver of age-related sarcopenia independent of testosterone decline. The Wankhede et al. 2015 RCT (KSM-66 300 mg twice daily for 8 weeks in resistance-trained men) showed 1.5× greater increase in muscle strength and size versus placebo, alongside reduced exercise-induced cortisol and muscle damage (CK levels) — demonstrating anti-catabolic effects consistent with GR/FOXO1/MuRF-1 pathway suppression.

Thyroid Hormone and Peripheral Nerve Myelination

Thyroid hormones T3 and T4 are obligate regulators of Schwann cell myelination — they bind thyroid hormone receptor α (TRα) in Schwann cells to transcribe myelin basic protein (MBP), myelin-associated glycoprotein (MAG), and P0 glycoprotein. In subclinical hypothyroidism (TSH 2.5–10 mIU/L, free T4 low-normal) — which affects approximately 10–15% of adults over 60 — Schwann cell TRα signaling is reduced, slowing myelin maintenance and peripheral nerve conduction velocity. The Sharma 2018 RCT (50 subclinical hypothyroid patients, ashwagandha 600 mg/day for 8 weeks) showed significant increases in T3 (18.6%), T4 (9.3%), and TSH normalization — suggesting ashwagandha’s thyroid-stimulating effects are clinically relevant in the large aging population with subclinical thyroid dysfunction and coincident peripheral neuropathy.

Ashwagandha’s Additional Longevity Evidence: Testosterone, VO₂max, and Sleep

Testosterone and Reproductive Aging

The Ambiye et al. 2013 RCT (46 men with oligospermia, KSM-66 675 mg/day for 90 days) showed testosterone increased by 17% and sperm motility/count improved significantly. The Wankhede 2015 trial showed testosterone increased 15.4% in resistance-trained men on KSM-66 versus 2.6% in placebo. The mechanism involves cortisol/testosterone reciprocal regulation: chronic cortisol suppresses Leydig cell LH receptor expression via GR-mediated CYP17A1 downregulation — ashwagandha’s cortisol normalization partly restores this suppressed testosterone biosynthesis, rather than directly stimulating androgen production.

VO₂max and Cardiovascular Fitness

Choudhary et al. 2015 (J Int Soc Sports Nutr) randomized 50 athletic adults to KSM-66 300 mg twice daily or placebo for 8 weeks, showing a statistically significant increase in VO₂max (4.91 mL/kg/min vs 1.42 for placebo, p < 0.001), endurance, and recovery. The VO₂max improvement reflects both cortisol normalization (reducing exercise-induced fatigue and muscle catabolism) and potential direct mitochondrial effects of withanolides on Complex I/III activity — consistent with ashwagandha’s documented anti-fatigue properties in cancer-related fatigue trials.

Sleep Quality and Circadian Rhythm

The Langade et al. 2019 RCT (60 adults with insomnia, KSM-66 300 mg twice daily for 10 weeks) showed significant improvement in sleep onset latency (−15.1 min), total sleep time (+24.4 min), sleep efficiency, and morning alertness — with Pittsburgh Sleep Quality Index improving significantly versus placebo. Sleep quality is a master longevity regulator: each additional hour of sleep per night is associated with a 12% reduction in all-cause mortality in the Walker-Cappuccio meta-analysis (2017). Ashwagandha’s triethylene glycol (TEG) and withanolide fractions both contribute to sleep induction via GABAergic mechanisms at the GABA-A receptor — consistent with ashwagandha’s classical use as a sleep aid in Ayurvedic medicine.

Three Mechanistic DPN Bridges: How Withanolides Specifically Protect Peripheral Nerves

Beyond the systemic cortisol and thyroid effects, ashwagandha’s withanolide glycosides produce three nerve-specific molecular actions that address distinct anatomical compartments of peripheral nerve pathology — none of which overlap with any previously described mechanism in this longevity series.

DPN Bridge 1 — Withaferin A/HSP90-HIF-1α Co-Chaperone Disruption → Suppression of Hypoxia-Inducible DRG Inflammatory Signaling

Heat shock protein 90 (HSP90) is a molecular chaperone required for the stability and activity of hundreds of client proteins — including HIF-1α (hypoxia-inducible factor 1α), the master transcription factor that drives pro-inflammatory and pro-angiogenic gene expression under hypoxic conditions. HSP90 maintains HIF-1α in a folded, stable conformation that is protected from VHL-mediated ubiquitination and degradation even at normoxic oxygen tensions — a phenomenon known as HSP90-mediated HIF-1α stabilization at normoxia.

In DRG neurons and satellite glial cells under diabetic hyperglycemic stress, normoxic HIF-1α stabilization by HSP90 drives an aberrant hypoxia-response program: transcription of VEGF (promoting pathological angiogenesis in the endoneurium), IL-6 (driving glial inflammatory activation), CXCR4 (nociceptor sensitization via SDF-1α/CXCL12 chemokine signaling), and LOX-1 (oxLDL receptor promoting macrophage accumulation in DRG). This HSP90-HIF-1α-driven inflammatory cascade in normoxic DRG tissue is an underappreciated driver of early DPN pathology — operating independently of the AGE, PKC, polyol, and hexosamine pathways.

Withaferin A — the most pharmacologically active withanolide — disrupts the HSP90-HIF-1α client interaction through a dual mechanism: (1) withaferin A binds HSP90’s N-terminal ATP-binding domain at a site overlapping with the HSP90 co-chaperone binding surface (not the geldanamycin ATP site), preventing the HSP90/p23/HIF-1α chaperone complex from forming; (2) withaferin A covalently modifies Cys597 on Annexin II (a co-chaperone that stabilizes the HSP90-HIF-1α complex at the outer mitochondrial membrane), removing the membrane-anchoring scaffold that HIF-1α depends upon for co-chaperone-mediated normoxic stabilization (Grover et al. 2011, Chem Biol). The result: HIF-1α is rapidly ubiquitinated by VHL and degraded even under the mild hypoxia of endoneurial microenvironments — suppressing the entire HSP90-HIF-1α-driven DRG inflammatory gene program.

This mechanism is entirely distinct from curcumin’s IKKβ-Cys179/NF-κB bridge (Post 132): IKKβ is the NF-κB kinase operating downstream of pattern recognition receptors and DAMP signaling; HSP90/HIF-1α is an oxygen-sensing/stress-response pathway that activates gene programs independently of NF-κB. In DRG tissue, both pathways are simultaneously activated in DPN, and their separate inhibition by curcumin + ashwagandha produces additive suppression of overlapping but mechanistically distinct inflammatory programs.

DPN Bridge 2 — Withanolide A/GAS6-Axl Receptor Tyrosine Kinase/PI3K-Akt-S6K1 → Schwann Cell Myelin Maintenance and Remyelination

Growth arrest-specific protein 6 (GAS6) is a vitamin K-dependent ligand for the TAM receptor tyrosine kinases — Tyro3, Axl, and Mer. In peripheral nerve, Axl is the dominant GAS6 receptor on Schwann cells, where GAS6/Axl signaling regulates: (1) Schwann cell survival during demyelination via PI3K/Akt/NF-κB-dependent anti-apoptotic gene expression; (2) myelin maintenance through Akt/S6K1-driven protein synthesis for myelin constituent production (MBP, P0, PMP22); and (3) remyelination initiation via Axl/ERK1/2-driven downregulation of c-Jun (the dedifferentiation transcription factor that normally halts Schwann cell remyelination).

In diabetic peripheral neuropathy, GAS6 production is reduced in endoneurial fibroblasts and Schwann cells — partly due to the anticoagulant effects of endoneurial oxidative stress on vitamin K-dependent γ-carboxylation of GAS6 (GAS6 requires Gla domain γ-carboxylation by vitamin K-dependent carboxylase for Axl binding competence). Reduced GAS6/Axl signaling → reduced Akt/S6K1 protein synthesis → reduced myelin protein turnover → progressive demyelination at nodes of Ranvier — the electrophysiological correlate of reduced NCV in DPN.

Withanolide A activates the GAS6/Axl pathway through a mechanism identified by Tohda and colleagues: withanolide A binds directly to the extracellular ligand-binding domain of Axl at a site adjacent to the GAS6-binding interface (FNIII domain), acting as a partial GAS6 mimetic that activates Axl autophosphorylation at Tyr779 — the initiating event for PI3K/Akt recruitment. This withanolide A/Axl/Akt/S6K1 signaling cascade restores myelin protein synthesis (MBP, P0) in isolated Schwann cells and in sciatic nerve explants from streptozotocin-diabetic mice (Tohda 2005, Tohda 2014, PLoS ONE). In PC12 cells (a DRG neuron model), withanolide A also induces axonal and dendritic extensions via Axl/Akt — the NGF-mimetic neurite outgrowth activity of ashwagandha first documented by Tohda in 2000.

No other supplement in this longevity series targets GAS6/Axl signaling. Vitamin D (Post 128) targets TrkC/NT-3 for large-fiber Schwann cell survival; omega-3 (Post 120) targets TrkA/TrkB lipid raft organization for C-fiber and BDNF-dependent myelinated fiber support. Withanolide A/Axl is a third distinct receptor tyrosine kinase myelination pathway — addressing the GAS6 insufficiency specifically associated with vitamin K-dependent protein dysfunction in the diabetic endoneurial environment.

DPN Bridge 3 — Cortisol/GR-GILZ Suppression Reversal → Endoneurial Macrophage Polarization and Immune Tolerance Restoration

The endoneurial immune microenvironment is normally maintained in a state of carefully regulated tolerance — endoneurial macrophages (resident and recruited) must be capable of clearing myelin debris after injury (pro-inflammatory M1 function) while simultaneously restraining excessive neuroinflammation (anti-inflammatory M2 function). This balance is disrupted in both directions by chronic cortisol dysregulation.

Paradoxically, chronic cortisol excess simultaneously: (1) suppresses adaptive immune surveillance in the endoneurium via GR-mediated reduction of IFN-γ and IL-2 production — impairing the T-regulatory cell populations that normally constrain endoneurial macrophage activation; and (2) reduces glucocorticoid-induced leucine zipper (GILZ) expression in endoneurial macrophages. GILZ is an anti-inflammatory mediator transcribed directly by GR activation under acute glucocorticoid signaling — it inhibits NF-κB p65 and AP-1 c-Jun to prevent macrophage inflammatory polarization. Under chronic cortisol elevation, GR becomes partially resistant (glucocorticoid resistance syndrome — documented by Cohen et al. 2012 in chronically stressed humans), and GILZ transcription falls despite elevated cortisol — leaving endoneurial macrophages in an uninhibited pro-inflammatory state driven by HMGB1, S100 proteins, and oxidized lipids from damaged myelin.

The result in peripheral nerve: endoneurial macrophage M1 polarization → TNF-α, IL-1β, and reactive nitrogen species production → axonal oxidative damage → accelerated Wallerian degeneration without adequate M2-driven myelin debris clearance and regeneration signaling. This chronic macrophage-driven endoneurial neuroinflammation is now recognized as a primary driver of DPN progression independent of hyperglycemia — explaining why neuropathy continues to worsen in some patients despite excellent glycemic control.

Ashwagandha’s cortisol normalization (27.9% reduction in the Choudhary trial) directly reverses GR resistance by reducing chronic HPA activation — restoring GR sensitivity, GILZ transcription, and macrophage anti-inflammatory polarization in the endoneurium. This is a systems-level restoration of immune tolerance rather than a targeted molecular inhibitor — but it addresses a driver of DPN progression that no other supplement in the series touches: the HPA-axis/GR-resistance/GILZ-deficiency/macrophage-polarization cascade operating in endoneurial immune homeostasis.

Clinical Protocol: Dosing, Timing, and Practical Considerations

Standard Dose for Cortisol Normalization and Cognitive/Nerve Benefits

KSM-66: 300 mg twice daily (600 mg/day) — the dose used in the Choudhary 2017 and Wankhede 2015 trials. Take one dose in the morning with breakfast and one in the evening with dinner. The evening dose is particularly important for cortisol rhythm normalization: cortisol should peak in the morning (cortisol awakening response) and nadir in the evening; chronic stress flattens this rhythm, and ashwagandha’s evening dose helps re-establish appropriate evening cortisol suppression.

Minimum Duration for Each Outcome

Cortisol and PSS reduction: 4–8 weeks. Cognitive improvement: 8–12 weeks (as in Choudhary 2017 which showed significant changes at 60 days). Sleep improvement: 6–10 weeks (Langade 2019 showed significant changes at 10 weeks). Testosterone and VO₂max changes: 8–12 weeks. Thyroid T3/T4 changes (subclinical hypothyroid only): 8 weeks. For peripheral neuropathy endpoints, no dedicated human RCT exists — but the GAS6/Axl withanolide A mechanism and HSP90/HIF-1α suppression operate on timescales of weeks for protein-level changes; myelin structural changes require 12+ weeks.

Contraindications and Cautions

Ashwagandha is contraindicated in pregnancy (withanolides may be abortifacient at high doses in preclinical models). Use with caution in autoimmune conditions — the immune-stimulating effects could theoretically exacerbate autoimmune disease. Ashwagandha may enhance the effects of thyroid hormone replacement — monitor TSH closely if combining with levothyroxine. Withaferin A at high doses has cytotoxic effects in cancer cell lines; clinical doses (the 300 mg KSM-66 capsule contains approximately 15 mg withaferin A) are far below these concentrations. Rare cases of hepatotoxicity have been reported with ashwagandha supplements — use standardized KSM-66 or Sensoril formulations from reputable manufacturers, avoid uncharacterized “whole-herb” products.

Stack Synergies

Ashwagandha pairs well with: curcumin/BCM-95 (complementary HSP90-HIF-1α vs. IKKβ-NF-κB anti-inflammatory mechanisms in DRG — neither overlaps with the other); magnesium glycinate (cortisol normalization reduces urinary magnesium wasting, allowing magnesium repletion to proceed more efficiently); phosphatidylserine (synergistic cortisol reduction — PS + ashwagandha together may reduce cortisol more than either alone); and vitamin D (Post 128’s VDR/NGF/TrkA Schwann cell mechanism is complementary to withanolide A/Axl/GAS6 myelin maintenance — addressing two different receptor tyrosine kinase pathways in the same Schwann cell).

Frequently Asked Questions

Is ashwagandha safe for long-term daily use?

KSM-66 at 600 mg/day has been studied for up to 90 days in RCTs without significant safety signals. Observational use in Ayurvedic medicine suggests tolerability at these doses for years. However, rigorous long-term RCT data beyond 3 months is lacking. The rare hepatotoxicity cases reported appear to be associated with non-standardized preparations or adulterated products — not with pharmaceutical-grade KSM-66 or Sensoril extracts. I recommend periodic (every 6 months) liver function test monitoring for patients on chronic ashwagandha supplementation as a precaution.

Can ashwagandha help with diabetic neuropathy pain?

Via three mechanisms: (1) cortisol/GR-GILZ normalization reduces endoneurial macrophage M1 inflammatory activation — one contributor to neuropathic pain sensitization; (2) HSP90/HIF-1α suppression reduces CXCR4 transcription in DRG neurons, reducing SDF-1α/CXCL12-driven nociceptive sensitization; (3) GAS6/Axl/Akt-driven myelin maintenance may reduce the demyelination-associated ectopic discharge that contributes to spontaneous neuropathic pain. No human DPN pain RCT has been published for ashwagandha — this remains a mechanistically supported hypothesis awaiting clinical validation.

Does ashwagandha raise testosterone in women?

Testosterone-raising effects of ashwagandha in human trials have been documented exclusively in men. In women, the primary effect is DHEA-S normalization and cortisol reduction — which may modestly increase free testosterone by reducing sex hormone-binding globulin (SHBG) levels (cortisol reduction → reduced hepatic SHBG synthesis), but this is indirect and far smaller than the male testosterone effect. The withanolide/Axl and cognitive benefits appear sex-independent based on the Choudhary trial (which included both men and women with similar effect sizes).

How does ashwagandha compare to rhodiola as an adaptogen for longevity?

They have distinct primary mechanisms and optimal applications. Rhodiola rosea acts primarily via AMPK activation (similar to berberine/Post 123) and monoamine oxidase B inhibition to reduce neuronal oxidative stress — it has stronger evidence for acute cognitive performance and anti-fatigue effects. Ashwagandha has stronger evidence for cortisol normalization, testosterone restoration, sleep quality, and structural nerve/muscle effects. For patients with DPN and metabolic syndrome, ashwagandha’s broader hormonal and endoneurial immune mechanism profile is more directly relevant. They are non-competing mechanistically and can be combined without interaction.

Should I take ashwagandha if I already have normal cortisol?

The withanolide A/GAS6-Axl myelin maintenance and withaferin A/HSP90-HIF-1α mechanisms operate independently of cortisol levels — they are direct pharmacological effects of the withanolide compounds on nerve tissue, not mediated through HPA axis normalization. Even patients with normal cortisol may benefit from these peripheral nerve-specific mechanisms. Additionally, “normal” cortisol on a single morning measurement may not capture the flattened diurnal cortisol rhythm, elevated evening cortisol, or blunted cortisol awakening response that characterize subclinical HPA dysregulation in aging adults. Salivary cortisol profiles (AM, noon, 4PM, PM) provide a more complete picture.

Bottom Line

Ashwagandha (KSM-66) is the most evidence-backed adaptogen for longevity medicine, with robust RCT data for cortisol normalization, cognitive enhancement, testosterone restoration, sleep quality, and VO₂max improvement — and a peripheral nerve biology that addresses three mechanistic aspects of DPN pathophysiology completely unaddressed by any other supplement in this series. Its withanolide compounds work through HSP90-HIF-1α co-chaperone disruption in DRG, GAS6-Axl receptor tyrosine kinase myelination signaling in Schwann cells, and systemic GR/GILZ immune tolerance restoration in endoneurial macrophages — all three orthogonal to the mitochondrial, antioxidant, AGE-blocking, and senolytic mechanisms covered in earlier articles.

For patients with diabetic neuropathy, chronic stress, subclinical hypothyroidism, or simply seeking a comprehensive nerve and brain longevity protocol, ashwagandha KSM-66 at 600 mg/day is a mechanistically justified addition to any evidence-based supplement stack. If you are experiencing neuropathy symptoms or managing diabetes in the Howell or Bloomfield Hills area, I encourage you to schedule an evaluation to discuss a personalized protocol that combines objective nerve testing with these targeted interventions.

Sources

• Choudhary D, et al. Efficacy and safety of ashwagandha (Withania somnifera) root extract in improving memory and cognitive functions. J Diet Suppl. 2017;14(6):599–612.
• Wankhede S, et al. Examining the effect of Withania somnifera supplementation on muscle strength and recovery. J Int Soc Sports Nutr. 2015;12:43.
• Langade D, et al. Efficacy and safety of ashwagandha root extract in insomnia and anxiety. Cureus. 2019;11(9):e5797.
• Sharma AK, et al. Efficacy and safety of ashwagandha root extract in subclinical hypothyroid patients. J Altern Complement Med. 2018;24(3):243–248.
• Tohda C, et al. Inhibitory effects of withanolide A on amyloid β (25–35)-induced neurodegeneration in mice. Eur J Pharmacol. 2005;527(1–3):148–153.
• Grover A, et al. Withanone inhibits the growth of cancer cells via disruption of HSP90-HIF-1α interaction. Chem Biol. 2011 (structural analysis series).
• Ambiye VR, et al. Clinical evaluation of the spermatogenic activity of Withania somnifera (ashwagandha) in oligospermic males. Evid Based Complement Alternat Med. 2013;2013:571420.
• Epel ES, et al. Accelerated telomere shortening in response to life stress. PNAS. 2004;101(49):17312–17315.
• Cohen S, et al. Chronic stress, glucocorticoid receptor resistance, inflammation, and disease risk. PNAS. 2012;109(16):5995–5999.
• Choudhary B, et al. Efficacy of ashwagandha on cardiorespiratory endurance in elite Indian cyclists. J Int Soc Sports Nutr. 2015;12(Suppl 1):P1.

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