Ashwagandha for Energy and Stress: Why Root vs. Leaf Matters for Safety

Ashwagandha for Energy and Stress: Why Root vs. Leaf Matters for Safety

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#Ashwagandha for energy and stress#Ashwagandha liver toxicity#Ashwagandha clinical trials benefits#Ashwagandha side effects safety#Energy

Ashwagandha supplements can be made from the root, the leaf or both. That difference matters if you are considering ashwagandha for energy and stress, because the trials behind the marketing used different plant parts, extracts and doses, and regulators are now looking at whether the plant part affects liver risk. This explainer covers three things: what the clinical evidence shows for stress, cortisol, sleep and fatigue; where that evidence is thin; and which safety signals to weigh before buying a bottle, including liver injury, thyroid effects and drug interactions.

A Shrub Sold as an “Adaptogen”

Ashwagandha is an evergreen shrub found in parts of India, Africa, and the Middle East, and it has been used for over 3,000 years in Ayurvedic medicine. Today it is promoted as an “adaptogen,” a substance used to help the body adapt to stress. Supplements are promoted for stress and anxiety, sleep, male infertility, and athletic performance.

Supplements typically contain root, leaf, or root/leaf extracts, and some use trademarked ingredients such as KSM-66®, Sensoril®, or Shoden®. The extracts contain more than 200 primary and secondary metabolites, and the concentration of withanolides can vary depending on whether the leaf or root part has been used.

Ashwagandha belongs to the Solanaceae family. People eat potato tubers, but the leaves contain much higher levels of natural plant toxins. Different parts of one plant can have different chemistry, so evidence about one part doesn’t automatically apply to another.

What Do Clinical Trials Show for Stress, Sleep and Fatigue?

A 2024 meta-analysis in the journal Explore pooled 9 studies with 558 patients and found Perceived Stress fell by 4.72, Anxiety by 2.19, and serum cortisol by 2.58 compared with placebo (the stress figure is points on the Perceived Stress Scale). The trials used 125–600 mg daily for 30–90 days, with both root-only and root-and-leaf formulations.

StudyParticipantsDurationExtract and doseFinding
Stress meta-analysisNine randomized controlled trials involving 558 patients30–90 daysRoot or root+leaf, 125–600 mgLower stress, anxiety, cortisol
2021 systematic review and meta-analysis of five studies on sleepA total of 372 adults took ashwagandha or placebo for 6 to 12 weeks6–12 weeksKSM-66 250–600 mg; Shoden 120 mgSmall but significant sleep gain
Shoden sleep trial150 adults, 18–656 weeksRoot + leafImproved sleep
Witholytin trial111 overweight adults aged 40–7512 weeksRoot, 200 mg twice dailyLess fatigue, not less stress (industry-linked trial)

The sleep meta-analysis found a small but significant effect on improving sleep, and all the studies were conducted in India. In the Witholytin trial, which bears most directly on the “energy” claim, ashwagandha did not reduce perceived stress, but it did reduce fatigue. For exercise, NCCIH says there isn’t enough evidence to determine if it helps athletic performance.

The caveats matter. NCCIH notes that many studies have had small sample sizes and used a variety of preparations. The NIH Office of Dietary Supplements says the trials were mostly fairly small in size and of short duration, and that most were conducted as part of a traditional medical system. One liver-injury case series concludes that conclusive evidence from rigorous, replicated trials does not exist.

Ashwagandha Liver Toxicity: Rare but Documented

NCCIH describes liver injury as rare, but notes a number of cases that link liver injury to ashwagandha supplements. Reports have been notable in medical literature since 2017. In one U.S. case, a 41-year-old woman took a single-ingredient over-the-counter supplement for 60 days and developed acute liver failure requiring a transplant. In another, a patient increased the recommended dose 2–3 times to alleviate high stress before developing liver injury.

In 2023, a review of hospital records in India reported 8 cases of liver injury with single-ingredient preparations, including 3 patients with fatal outcomes. Five of the 8 patients already had chronic liver disease, and all 3 deaths were in people whose existing liver disease suddenly worsened. Australia’s Therapeutic Goods Administration issued a safety alert in 2024 highlighting that medicines and herbal supplements containing W. somnifera may be associated with liver injury in very rare cases; most of the reported liver injury cases resolved following discontinuation of the product, although some required medical treatment.

Not everyone reads this evidence the same way. India’s Ministry of Ayush published a 2024 dossier that found no evidence of intrinsic liver toxicity in the root. One proposed explanation for the cases points to withanone, a withanolide that carries electrophilic functional groups associated with adverse drug reactions. That idea is still a hypothesis, not a confirmed cause.

Side Effects and Who Should Avoid It

On short-term use, NCCIH says ashwagandha may be safe for up to 3 months. Long-term safety hasn’t been established. Common complaints include drowsiness, stomach upset, diarrhea, and vomiting.

These groups should avoid it or talk to a clinician first:

What the Label Doesn’t Tell You

In the U.S., dietary supplements are not approved by the FDA before they are sold. Manufacturers are responsible for evaluating their own products. KSM-66 claims “self-affirmed GRAS” status, but ashwagandha is not recognized as GRAS by the FDA. GRAS means “generally recognized as safe.” Regulators elsewhere are paying closer attention: the TGA says it is considering evidence on the role of different plant parts in liver injury.

In short, ashwagandha has a measurable but modest effect on stress and sleep over a few weeks. The evidence for extra energy is thinner, and the liver risk is rare but real. Before buying, check whether a product uses root or leaf, keep use short, and talk to a clinician if you take medications or have a liver, thyroid or autoimmune condition.

Sources

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