Ashwagandha

Ashwagandha (Withania somnifera) is a shrub used for centuries in traditional Ayurvedic medicine, commonly sold as a standardized root extract. It's marketed as an "adaptogen" — a substance claimed to help the body resist stress — and most modern research has focused on its withanolide compounds and their effects on perceived stress, anxiety, and cortisol, a hormone released during the body's stress response. Unlike magnesium or vitamin D, there's no deficiency state being corrected here — the claimed benefit is a direct pharmacological-style effect on stress physiology.

Meta-analysis level evidence: Akhgarjand C, et al. "Does Ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials," Phytotherapy Research, 2022. Pooling 12 RCTs (1,002 participants), ashwagandha supplementation significantly reduced both anxiety and stress scores versus placebo. A dose–response analysis suggested stress reduction was optimal around 300–600mg/day, while the anxiety signal held across a wider dose range. The authors rated the overall certainty of evidence as low, meaning more high-quality research could still change these estimates.

Read the meta-analysis →

A representative individual trial: Chandrasekhar K, Kapoor J, Anishetty S. "A Prospective, Randomized Double-Blind, Placebo-Controlled Study of Safety and Efficacy of a High-Concentration Full-Spectrum Extract of Ashwagandha Root in Reducing Stress and Anxiety in Adults," Indian Journal of Psychological Medicine, 2012. Using 300mg twice daily of a root extract standardized to ≥5% withanolides for 60 days, the ashwagandha group saw a 44% drop in Perceived Stress Scale scores (versus 5.5% for placebo) and a 27.9% reduction in serum cortisol (versus 7.9% for placebo). This is one of the more frequently cited trials behind the dosing used across the newer meta-analyses.

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Being honest about where this stands: per the NIH Office of Dietary Supplements, several placebo-controlled trials do show reduced perceived stress, anxiety, and cortisol, and some show modestly better sleep — but ashwagandha has only been studied for up to about 3 months at a time, trials vary widely in extract type and dose, and the NIH explicitly notes that long-term safety and efficacy beyond that window "is not known." This is a supplement with more consistent short-term signal than most, but not a settled, decades-deep evidence base like magnesium's deficiency-correction role.

Read the NIH fact sheet →

Trials have used a wide range of preparations — from 240mg to 1,250mg/day of standardized extract, up to 6,000–12,000mg/day of whole root powder in some anxiety trials — which makes a single dosing standard hard to pin down. Most of the stress/cortisol trials, including the one above, used 300mg twice daily (600mg/day total) of a root extract standardized to 5% or more withanolides, taken for 8 weeks or longer. There's no official RDA-style guideline the way there is for magnesium or omega-3, so "typical" here means what trials have actually tested, not an established recommended intake.

Thyroid effects: ashwagandha can measurably raise thyroid hormone levels. Sharma AK, Basu I, Singh S. "Efficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients,"The Journal of Alternative and Complementary Medicine, 2018 — a small trial (n=50) found 300mg twice daily for 8 weeks significantly lowered TSH and raised T3/T4 versus placebo in people with subclinical hypothyroidism. That's the intended effect in that population, but in anyone with normal thyroid function or hyperthyroidism, or anyone on thyroid medication like levothyroxine, it's a real interaction risk that can push thyroid hormone levels too high — this needs monitoring by a doctor, not self-management.

Read the thyroid trial →

Liver injury — rare but real: multiple published case reports describe ashwagandha-linked acute liver injury. Tóth M, Benedek AE, Longerich T, Seitz HK. "Ashwagandha-induced acute liver injury: A case report," Clinical Case Reports, 2023 — a 65-year-old woman developed jaundice about two weeks after starting ashwagandha, with a liver biopsy showing cholestasis and hepatocellular injury; she recovered over several months after stopping the supplement. The NIH's LiverTox database rates ashwagandha as a "likely" cause of clinically apparent liver injury, notes a typical latency of 2–12 weeks, and states that while most cases are mild and self-limited, rare instances of fatal liver injury or the need for emergency liver transplant have been reported, particularly in people with pre-existing liver disease.

Read the case report → ·Read the NIH LiverTox entry →

Pregnancy and breastfeeding: safety hasn't been established in pregnant or breastfeeding women, and Memorial Sloan Kettering's herb-drug interaction database advises this group avoid ashwagandha until more data exists.

Autoimmune conditions: ashwagandha may stimulate immune activity. In autoimmune disorders like lupus or rheumatoid arthritis, where the immune system is already overactive, that stimulation could make things worse rather than better — a reason to check with a doctor first rather than assume an adaptogen is automatically gentle.

Sedatives: ashwagandha has sedative-like properties of its own, so combining it with sedative medications or alcohol may add to drowsiness; some clinicians also recommend stopping it before scheduled surgery for the same reason.

Read MSK's ashwagandha safety overview →