The Ashwagandha Stress Study (Lopresti 2019) Explained: Dose, Extract and What It Means

What the Lopresti 2019 ashwagandha study tested

Lopresti and colleagues asked whether a standardised Withania somnifera root extract could ease anxiety and stress in healthy adults, and whether it changed the hormones linked to the stress response.^[1] The trial measured two kinds of outcome: rating scales for how participants felt, and blood levels of cortisol, DHEA-S and testosterone.^[1] That makes it useful to formulators, because it shows where the evidence is strong and where it is weak.

Many brands quote this paper on packs and in sales decks, often with the wrong extract or dose attached. This article sets out what the trial actually tested and what it found. It also shows how later meta-analyses read the same question. It is a review of published research for product developers, not medical advice. For the wider market picture, see FRL’s overview of adaptogenic herbs in stress-support supplement brands.

Study design: who took part, which extract and what dose

Randomised, double-blind, placebo-controlled

The trial ran for 60 days and enrolled 60 healthy adults aged 18–65 (37 men and 23 women) at two centres in India, in Bhopal and Pune.^[1] Participants were randomised to the extract or to a placebo of roasted rice powder in identical capsules, and neither participants nor investigators knew who took which.^[1] The abstract describes participants as having “self-reported high stress”. The entry criterion, however, was a Hamilton Anxiety Rating Scale (HAM-A) score of 6–17, and the authors describe the group as mildly stressed.^[1] The trial did not study people with a diagnosed anxiety disorder.

The extract and dose: Shoden, not KSM-66

Participants took one 240 mg capsule of Shoden once daily after dinner.^[1] Shoden is a root extract made with 70:30 ethanol:water and standardised by HPLC to not less than 35% withanolide glycosides, which is about 84 mg of withanolide glycosides per capsule.^[1] The authors note that 240 mg is lower than the 600 mg dose used in most earlier ashwagandha trials.^[1]

This is the most common error in how the paper is quoted. It is not a KSM-66 study. KSM-66 is a different branded root extract with its own specification and its own trials. A result from one extract cannot be moved to another.

Who funded it

Arjuna Natural Ltd, which makes Shoden, funded the trial and manufactured the capsules. The principal investigators declared no competing interests. The lead author reported past funding from the same company for unrelated studies.^[1] Industry funding is common in botanical trials and does not invalidate a result. It should still be stated whenever the trial is used to support a product.

What the study found

All 60 participants completed the trial, and no adverse events were reported.^[1] Compared with placebo, the extract group had a significantly greater fall in HAM-A anxiety scores (P = .040). The difference in the Depression, Anxiety and Stress Scale (DASS-21) was not significant (P = .096).^[1] Morning cortisol fell by 23% in the extract group against a 0.5% rise with placebo (P < .001 between groups), and DHEA-S also fell more with the extract (P = .004).^[1]

The careful reading is a clear hormonal signal, a modest anxiety-scale signal and no significant effect on the broader stress questionnaire. That does not support a simple “reduces stress” headline. Within-group changes also need care: HAM-A fell by 41% with the extract, but it also fell by 24% with placebo.^[1]

Table 1. Main outcomes of the 2019 trial (extract vs placebo, 60 days)

Source: Lopresti et al. (2019).^[1]

Strengths and limitations

The strengths are a placebo control, double blinding, a named and specified extract, a single fixed dose and full completion.^[1] The authors list the limitations themselves:^[1]

• a small sample of mildly stressed, healthy adults, not a clinical population;
• one dose, one extract and one country (India);
• 60 days of intake, with no follow-up after stopping;
• too few participants to link hormone changes to symptom changes;
• diet, occupation and economic conditions were not examined.

The authors call for larger studies in different populations, over longer periods.^[1] For a brand, the trial is one data point for one extract. It does not establish ashwagandha as a category.

How the trial compares with later meta-analyses

Two recent meta-analyses pool several trials, and they show why the outcome must be named as well as the extract. A 2024 review of 9 randomised trials (558 participants) found lower Perceived Stress Scale (PSS) scores (mean difference −4.72), lower HAM-A anxiety (−2.19) and lower serum cortisol (−2.58) with ashwagandha than with placebo.^[3] A 2025 review pooled 7 trials reporting cortisol and 6 reporting PSS (488 participants in total). It confirmed lower cortisol (−1.16 µg/dL, P < 0.001) but found no significant effect on perceived stress (P = 0.40).^[2]

Table 2. Pooled analyses compared

Both reviews pool different extracts, doses and durations, so neither can say which extract works best. The 2025 review included only trials using at least 250 mg a day,^[2] so a 240 mg trial like Lopresti’s would not meet its dose criterion. Across both reviews, the cortisol evidence is more consistent than the perceived-stress evidence. In the 2024 review, four trials reported mild to moderate adverse events, and the authors say long-term safety needs more study.^[3]

Safety signals and regulatory context

A clean 60-day trial does not settle long-term safety, and regulators have become more cautious since 2019.

• Germany: in September 2024 the German Federal Institute for Risk Assessment (BfR) advised that children, pregnant and breastfeeding women and people with liver disease should not take ashwagandha supplements. It cited case reports of liver damage, including acute liver failure, and said the data do not allow a safe intake level to be set.^[6]
• India: a 2023 multi-centre case series from India described 8 patients with liver injury linked to single-ingredient ashwagandha products. Three patients with pre-existing chronic liver disease developed acute-on-chronic liver failure and died.^[7] A case series shows an association; it does not establish how often harm occurs.
• Denmark: trade press reported in 2023 that Danish authorities had acted against ashwagandha in food supplements after a 2020 Technical University of Denmark risk assessment, which concluded that a safe intake could not be set. Industry groups dispute that assessment.^[8]

India’s food regulator has also acted on plant part. On 16 April 2026, FSSAI issued an advisory that ashwagandha leaves may not be used in food products in crude, extract or any other form, and that only the roots and root extracts listed in Schedule IV of the 2016 nutraceutical regulations are permitted.^[5] The Ministry of Ayush issued a root-only directive the day before, which trade press reports also asks for the plant part to be declared on the label.^[9] On 12 May 2026, the Karnataka High Court reportedly stayed both directives for the eight companies that challenged them. The stay applied only to those petitioners, and a further hearing was listed for 8 June 2026.^[10] Check the current status of the case before you rely on either position. For the regulatory detail, see FRL’s guide to FSSAI nutraceutical regulations and its explainer on AYUSH licence vs the FSSAI nutraceutical route. FRL’s Ayurvedic nutraceutical toxicity and safety guide covers contaminants and herb–drug interactions.

What it means for herbal product formulators

Treat a trial as a specification

In herbal product development, a trial is a specification, not a slogan. In this trial, the extract (Shoden root extract, at least 35% withanolide glycosides), the dose (240 mg once daily), the duration (60 days) and the outcomes (HAM-A and morning cortisol) belong together.^[1] If your extract, dose or format differs, this trial is not your evidence, and you need data for your own material.

Match the marker to the evidence

The European Medicines Agency’s quality guideline for herbal medicinal products distinguishes three types of preparation. Standardised preparations are adjusted to constituents with known therapeutic activity. Quantified preparations are adjusted to active markers within a set range. All other preparations are defined by their production process and specification.^[4] The guideline covers medicines, not foods, but its terms are useful for specifications. A withanolide assay gives you a measurable target. Confirm that your assay method and marker match those of the extract in the evidence you cite, because withanolide figures from different methods are not directly comparable.

Specify root, and keep the paperwork

Specify root on the purchase specification and the certificate of analysis, and record extraction solvent and ratio. Keep a supplier declaration that no leaf is present. Our worked example of a 240 mg ashwagandha root-extract capsule shows how these choices turn into a development file.

Formulator’s note. Whenever you cite a trial, write the extract name, daily dose and duration beside it. Match the outcome scale (HAM-A, DASS-21, PSS or cortisol) to the wording you plan to use. Never transfer a result from one extract to another.

Conclusion

The 2019 trial is a useful anchor, but it supports one extract at one dose over 60 days. Its clearest effects were on morning cortisol and clinician-rated anxiety, not on a general stress score. Read it alongside the later meta-analyses and the safety and regulatory signals above. Name the extract, and keep any wording within what your own evidence and the applicable regulations allow. Answers to common development questions are in FRL’s herbal product development Q&A.

For brands & formulators

Food Research Lab’s herbal formulation team helps brands choose an extract, set the dose and build the specification around the evidence they plan to cite. We compare supplier specifications (plant part, solvent, marker and assay method) with the trial material, then design the format and stability plan. Our regulatory and scientific research team checks your intended wording against the evidence and the FSSAI or AYUSH route that applies. See our wider herbal product development work.

Talk to a formulation expert about your ashwagandha product or contact our team.

In this series

• Herbal product development process: the pillar guide: seven stages from claim to launch.
• AYUSH licence vs FSSAI: which regulatory route a herbal product takes in India.
• Standardised extract, HPLC and DNA testing: how to prove identity and strength.
• The ashwagandha stress study (Lopresti 2019) explained (this page): You are here.
• Ashwagandha capsule development: a worked example: one product from brief to stability-ready specification.
• Private-label herbal supplements in India: stock formulas versus your own.
• Herbal product development in India: 10 questions: short answers on extracts, testing, stability and regulation.
• Herbal formulation development service: work with our team on your product.

1. Lopresti, A. L., Smith, S. J., Malvi, H., & Kodgule, R. (2019). An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: A randomized, double-blind, placebo-controlled study. Medicine, 98(37), e17186. https://doi.org/10.1097/MD.0000000000017186 (open access: PMC6750292) (cited for design, participants, extract specification, dose, outcomes and P values, adverse events, funding and limitations).
2. Albalawi, A. A. (2025). Dual impact of ashwagandha: Significant cortisol reduction but no effects on perceived stress. A systematic review and meta-analysis. Nutrition and Health, 31(4), 1395–1408. https://doi.org/10.1177/02601060251363647 (cited for pooled cortisol and perceived-stress results, trial and participant numbers, and the ≥250 mg/day inclusion criterion).
3. Arumugam, V., Vijayakumar, V., Balakrishnan, A., Bhandari, R. B., Boopalan, D., Ponnurangam, R., Sankaralingam Thirupathy, V., & Kuppusamy, M. (2024). Effects of ashwagandha (Withania somnifera) on stress and anxiety: A systematic review and meta-analysis. EXPLORE, 20(6), 103062. https://doi.org/10.1016/j.explore.2024.103062 (cited for pooled PSS, HAM-A and cortisol results and the adverse-event and long-term safety statements).
4. European Medicines Agency, Committee on Herbal Medicinal Products. (2022). Guideline on quality of herbal medicinal products/traditional herbal medicinal products (EMA/HMPC/CHMP/CVMP/201116/2005 Rev. 3). https://www.ema.europa.eu/en/documents/scientific-guideline/final-guideline-quality-herbal-medicinal-productstraditional-herbal-medicinal-products-revision-3_en.pdf (cited for the definitions of standardised and quantified herbal preparations).
5. Food Safety and Standards Authority of India. (2026, April 16). Advisory regarding non-use of Ashwagandha (Withania somnifera) leaves in crude or extract or any other form in food products (F. No. RCD-15001/11/2021-Regulatory-FSSAI). https://fssai.gov.in/upload/advisories/2026/04/69e0d84fcac2fAdvisory%20on%20non%20use%20of%20ashwagandha%20leaves%20in%20crude%20or%20extract%20or%20any%20other%20form%20in%20food%20products-%20reg.pdf (cited for the leaf prohibition and the roots-only position under Schedule IV of the 2016 regulations).
6. German Federal Institute for Risk Assessment (BfR). (2024, September 10). Ashwagandha: Food supplements with potential health risks (Communication 39/2024). https://www.bfr.bund.de/cm/349/ashwagandha-food-supplements-with-potential-health-risks.pdf (cited for the advice to at-risk groups, liver-damage case reports and the lack of a safe intake level).
7. Philips, C. A., Valsan, A., Theruvath, A. H., Ravindran, R., Oommen, T. T., Rajesh, S., Bishnu, S., & Augustine, P. (2023). Ashwagandha-induced liver injury: A case series from India and literature review. Hepatology Communications, 7(10), e0270. https://doi.org/10.1097/HC9.0000000000000270 (cited for the 8 single-ingredient liver-injury cases and 3 deaths in patients with chronic liver disease).
8. Hancocks, N. (2023, May 18). Growing concerns over safety of ashwagandha in EU member states. NutraIngredients. https://www.nutraingredients.com/Article/2023/05/17/Growing-concerns-over-safety-of-ashwagandha-in-EU-member-states (trade press; cited for Danish action on ashwagandha supplements and the 2020 DTU risk assessment).
9. Sherman, A. (2026, April 28). India bans ashwagandha leaf use in any form, industry reacts. NutraIngredients. https://www.nutraingredients.com/Article/2026/04/28/india-bans-ashwagandha-leaf-use-in-any-form-industry-reacts (trade press; cited for the Ministry of Ayush root-only and plant-part labelling directive).
10. Jha, S. (2026, May 20). Karnataka HC temporarily stays FSSAI ban on ashwagandha leaves. The South First. https://thesouthfirst.com/health/karnataka-hc-temporarily-stays-fssai-ban-on-ashwagandha-leaves/ (news report; cited for the 12 May 2026 interim stay, its scope and the 8 June hearing date).