RCTJadad 5/5RandomizedDouble-BlindPlacebo-Controlled

Zenroot Ashwagandha: A Low-Dose, High-Absorption Formula Cuts Stress, Anxiety, and Sleep Trouble in 12 Weeks

Advances in TherapyAugust 28, 2025Vol. 42 (10)

Summary

If you've shopped for an ashwagandha supplement lately, you've probably noticed doses ranging from 120 mg to 600 mg and withanolide percentages from 1.5% to 35%, with little guidance on what actually matters. A new randomized, double-blind, placebo-controlled trial published in Advances in Therapy (2025) tested a specific formulation — Zenroot™ (ZEN), just 125 mg/day standardized to 1.5% total withanolides (~1.88 mg) — against a matching placebo in 90 adults (ages 18–55) with mild-to-moderate, non-chronic stress (stress lasting under three months, screened using the Perceived Stress Scale).

Over 12 weeks (84 days), researchers tracked stress (PSS), anxiety (Beck Anxiety Inventory), mood (Profile of Mood States), sleep quality (Pittsburgh Sleep Quality Index), and objective physiological markers — skin conductance response, heart-rate variability (HRV), serum cortisol, and salivary alpha-amylase.

The headline results: by day 84, the ZEN group's perceived stress score dropped by 7.4 points versus a slight increase (+0.8) in the placebo group — a statistically significant gap (p<0.05). Every single ZEN participant (100%) hit the threshold researchers consider a "minimum clinically important difference" (MCID), versus just 13% on placebo. Anxiety scores fell by 8.3 points on ZEN versus a 2.3-point rise on placebo (91% hit MCID). Mood disturbance dropped by 54 points versus a 16-point worsening on placebo. Sleep quality (PSQI) improved meaningfully too. Objective stress markers told a similar story early on: skin conductance and HRV (a marker of parasympathetic "rest-and-digest" activity) improved significantly by day 14 — faster than most subjective symptoms changed.

Notably, serum cortisol and salivary alpha-amylase — blood/saliva stress hormone markers — did NOT differ significantly between groups. The likely explanation: participants started with normal cortisol levels, so there was little room to move ("floor effect"). This mirrors a broader pattern in the ashwagandha literature — a 2025 systematic review and meta-analysis (Bachour et al., PMC12242034) of 15 RCTs found ashwagandha reliably lowers cortisol but effects on subjective "perceived stress" are less consistent across studies, essentially the opposite pattern seen here. That divergence is worth remembering: different ashwagandha extracts, doses, and populations produce different result profiles, so no single trial should be read as "ashwagandha's effect," full stop.

What makes ZEN interesting isn't the extract's potency on paper — 1.5% withanolides is low compared to popular 5–35% branded extracts — but a companion bioavailability study (also in Advances in Therapy, 2025) reporting that 125 mg of ZEN achieved higher plasma withanolide concentrations than 500–600 mg doses of two commercial competitors with 5–10% withanolide content. If replicated, this suggests formulation and absorption technology can matter as much as raw withanolide percentage on a label.

What This Means For You

If you're stress-prone but not clinically diagnosed with an anxiety disorder, this trial suggests a low-dose (125 mg/day), well-absorbed ashwagandha formulation taken once daily after breakfast for at least 4 weeks — with fuller benefits by 8–12 weeks — may meaningfully ease everyday stress, mood dips, and sleep quality. Don't expect overnight results: day-14 changes were mostly limited to objective physiological markers (skin conductance, HRV), while subjective stress/anxiety/mood improvements versus placebo emerged around week 4 and grew through week 12.

When shopping for ashwagandha, this study reinforces two label-reading habits: (1) check for standardization to total withanolides via HPLC (ideally referencing the USP's seven-peak method, as this study did) rather than trusting vague "extract" claims, and (2) recognize that milligram dose and withanolide percentage alone don't guarantee effect — absorption/bioavailability technology can let a lower-dose product outperform a higher-dose one, per the companion pharmacokinetic study on this exact ingredient. That said, this is evidence for one branded formulation (Zenroot™), not a blanket case that "less is more" for every ashwagandha product on shelves.

Who might benefit most: adults with mild-to-moderate, situational (not chronic, not clinically severe) stress and sleep complaints — the population actually studied. People with elevated baseline cortisol or chronic/severe stress weren't well represented, so it's unclear the same effect size would hold for them; the authors explicitly call for that population to be studied next.

Caution: this is not a substitute for treatment of diagnosed anxiety or depression — people on anxiolytics, antidepressants, antipsychotics, or sleep medications were excluded from the trial, so no data exists on interactions with those drugs. Athletes/fitness enthusiasts should note this trial didn't test performance or muscle-related outcomes (unlike some other ashwagandha studies) — its relevance here is stress/recovery/sleep, not strength gains.

Important Considerations

This trial has real strengths — it's randomized, double-blind, placebo-controlled, prospectively registered (CTRI/2024/03/063786), with zero dropouts and a Jadad quality score of 5/5 — but several limitations temper the takeaway. First, it was conducted at a single center in India with 90 adults ages 18–55 with mild-to-moderate, non-chronic (under 3 months) stress; results may not generalize to chronic stress, older adults, or clinically diagnosed anxiety/mood disorders. Second, the "objective" biomarkers most people associate with stress — cortisol and alpha-amylase — showed no significant treatment effect, likely because participants' baseline levels were already normal; this is an important asterisk given how heavily cortisol reduction is marketed for ashwagandha products generally. Third, several secondary outcomes (HRV, skin conductance) lost statistical significance at later timepoints or showed inconsistent within- vs. between-group patterns — the authors themselves note some "significant" between-group differences (e.g., HRV-SDNN, salivary amylase at day 56) weren't attributable to a real drug effect once within-group changes were checked. Fourth, the study was funded/product supplied by the ingredient manufacturer (OmniActive Health Technologies), a common but relevant conflict-of-interest consideration for supplement trials. Finally, this is one study of one specific branded formulation — it cannot be generalized to "ashwagandha" as a category, since dose, extraction method, and withanolide profile vary enormously between commercial products, and a 2025 meta-analysis of 15 other ashwagandha RCTs found a different balance of effects (reliable cortisol reduction, less consistent perceived-stress benefit). Anyone with an existing anxiety/mood disorder, on psychiatric medication, pregnant, or breastfeeding should consult a healthcare provider before starting any ashwagandha supplement.

Terms Explained

Ashwagandha (Withania somnifera)A traditional Ayurvedic herb classified as an 'adaptogen,' believed to help the body adapt to and recover from stress.

WithanolidesThe steroidal lactone compounds in ashwagandha root thought to drive most of its stress-reducing and other pharmacological effects; total withanolide % on a label indicates concentration, not necessarily potency.

AdaptogenA category of herbal substances claimed to help the body resist and recover from physical or psychological stress by supporting normal physiological function.

Perceived Stress Scale (PSS)A 10-item questionnaire (0–40 points) measuring how stressful a person perceives their life to be; lower scores mean less perceived stress.

Minimum Clinically Important Difference (MCID)The smallest change in a score that a person would consider meaningful in daily life, used to judge whether a statistically significant result is also practically significant.

Heart Rate Variability (HRV)The variation in time between heartbeats; higher HRV generally reflects better stress resilience and more parasympathetic ('rest and digest') nervous system activity.

Skin Conductance Response (SCR)A measure of sweat-gland activity on the skin that rises with sympathetic ('fight or flight') nervous system arousal, used as an objective stress indicator.

Salivary alpha-amylase (sAA)An enzyme in saliva that rises with sympathetic nervous system activation, sometimes used alongside cortisol as a biomarker of acute stress.

BioavailabilityThe proportion and rate at which a supplement's active compounds are absorbed into the bloodstream and available to act in the body — higher bioavailability can let a lower dose work as well as, or better than, a higher one.

Double-blind, placebo-controlled trialA study design where neither participants nor researchers know who received the real treatment versus an inactive look-alike, reducing bias in reported results.

Technical Study Details

Study Design

Duration12 weeks

RegistrationClinical Trials Registry of India (CTRI): CTRI/2024/03/063786

Total Score

JADAD Quality Assessment

/ 5

評価詳細

Randomization

2 / 2

Is the study described as randomized?

Yes+1

Rationale: The article repeatedly and explicitly describes the study as "randomized" in the abstract, methods (study design), and results sections, including details about the randomization schedule generation, confirming randomization was mentioned.

Is the method of randomization described and appropriate?

Yes+1

Rationale: The article explicitly describes the randomization method: an independent, non-study-affiliated expert generated the randomization schedule using SAS statistical software (version 9.4) to ensure treatment balance. Computer-generated randomization is a recognized appropriate method under the Jadad scale, and using an independent expert (rather than study personnel) further supports allocation integrity. This is not an inappropriate method like alternation, date of birth, or hospital number.</rationale> </invoke>

Blinding

2 / 2

Is the study described as double-blind?

Yes+1

Rationale: The article explicitly and repeatedly describes the study design as "double-blind" both in the Abstract and in the Methods (Study Design and Procedures) section, satisfying the Jadad criterion for Q3.

Is the method of blinding described and appropriate?

Yes+1

Rationale: The article explicitly describes the blinding method: both the active (ZEN) and placebo products were formulated as capsules of the same fill weight (~280 mg) and identical scarlet red color, explicitly stated "to maintain blinding." This describes an appropriate double-blinding technique using an identical-appearing placebo capsule matched in color and weight to the active treatment, satisfying the criteria for a "yes" answer.</rationale> </invoke>

Dropouts/Withdrawals

1 / 1

Is there a description of dropouts and withdrawals?

Yes+1

Rationale: The article explicitly accounts for subject flow from screening through completion: 95 screened, 4 screen failures, 1 lost to follow-up prior to randomization, and then all 90 randomized subjects (45 ZEN, 45 placebo) completed the study with zero withdrawals/dropouts after randomization. It further specifies that no subjects discontinued treatment due to adverse events. This is also depicted in a CONSORT flow diagram (Fig. 1) explicitly labeled as showing "withdrawals." Since the number of withdrawals (zero) is clearly stated for each treatment group, this satisfies the Jadad criterion for describing withdrawals/dropouts.</rationale> </invoke>

Study Population

Sample Size90

Age Range18-55 years

ConditionNon-chronic mild to moderate perceived stress

Inclusion Criteria

Stressed male or female adults aged 18-55 years (inclusive)
BMI 18.5-29.9 kg/m2 (inclusive)
Mild to moderate stress: PSS score >=7 or <=26, of less than 3 months duration
Willingness to maintain regular eating patterns and activity level
Willingness to refrain from stress/anxiety/mood medications or supplements during the study
Willingness to abstain from alcohol 24 h before testing days
Willingness to abstain from caffeine 12 h before test days
Willingness to abstain from strenuous physical activity 12 h before test days
Agreement to maintain weight stability during trial
Willing to provide written informed consent and complete the study

Interventions

Zenroot (ZEN)

Treatment

Dose125 mg Ashwagandha powder (1.5% total withanolides, ~1.88 mg total withanolides) in a ~280 mg capsule

FrequencyOnce daily

Duration84 days

RouteOral

Placebo

Control

Dose~280 mg microcrystalline cellulose capsule

FrequencyOnce daily

Duration84 days

RouteOral

Outcomes

Outcome	Type	Effect	p-value
Perceived Stress Scale (PSS) score	Primary	-	p < 0.05Significant
Mindfield eSense Skin Response (Skin Conductance Rate)	Secondary	-	p < 0.05Significant
Heart Rate Variability - RMSSD	Secondary	-	p < 0.05Significant
Heart Rate Variability - SDNN	Secondary	-	p < 0.05Significant
Beck Anxiety Inventory (BAI) score	Secondary	-	p < 0.05Significant
Profile of Mood States (POMS) - Total Mood Disturbance	Secondary	-	p < 0.05Significant
Pittsburgh Sleep Quality Index (PSQI) - Global score	Secondary	-	p < 0.05Significant
Serum cortisol level	Secondary	-	-
Salivary alpha-amylase (sAA)	Secondary	-	-Significant

Safety

Serious AEs0

Dropout Rate0.0%

33.3% of ZEN group and 20% of placebo group experienced at least one AE. All AEs were mild except two (one moderate pyrexia in placebo, one moderate cough/cold in ZEN). All AEs were unrelated to study products, none led to discontinuation, and all resolved. No clinically significant abnormalities in hematology, renal, or hepatic function at study end.

Conclusion

ZEN (Zenroot Ashwagandha formulation with 1.5% total withanolides) at 125 mg/day for 84 days significantly reduced perceived stress (PSS) and anxiety (BAI) scores, improved mood (POMS) and sleep quality (PSQI), and improved objective stress markers (skin conductance response and HRV parameters, particularly at day 14) compared to placebo in adults with non-chronic mild to moderate stress. No significant between-group differences were seen in serum cortisol or salivary alpha-amylase. ZEN was safe and well tolerated with no treatment-related adverse events.

Limitations

Study population limited to non-chronic, mild-to-moderate stress subjects with stress duration less than 3 months, limiting generalizability to chronically stressed individuals
All subjects had serum cortisol levels within normal range at baseline, which may explain the lack of significant treatment effect on serum cortisol and salivary alpha-amylase
Diurnal variation and other factors (diet, exercise, sleep schedules) could influence cortisol levels despite standardized morning sample collection times
Authors note future studies should recruit subjects with above-normal cortisol/sAA levels and chronic stress, and use larger sample sizes