Ashwagandha (Withania somnifera) is one of the most heavily studied adaptogens on the market, and NOW Foods' version of it is one of the most widely sold on Amazon — which makes it a reasonable one to hold up against the actual clinical research, rather than the marketing language that usually surrounds it. This entry stays in one lane deliberately: what the cortisol, stress, and sleep-quality studies measured, and how this specific capsule's dose and standardization compares to what was actually tested.
Each vegetarian capsule contains 450 mg of Ashwagandha (Withania somnifera) root and leaf extract, standardized to a minimum of 2.5% total withanolides — roughly 11 mg of withanolides per capsule. The only other ingredients are hypromellose (the vegetable capsule shell), rice flour, and vegetable-source stearic acid; the formula is free of dairy, egg, gluten, soy, tree nuts, and gelatin. The label's suggested use is 1 capsule two to three times daily, which works out to about 900–1,350 mg of extract (roughly 22–34 mg of withanolides) a day if taken as directed — not a single fixed "one-a-day" dose. It's sold in 90-, 180-, and 240-capsule bottles.
Active ingredient: Ashwagandha root & leaf extract, standardized to min. 2.5% total withanolides — 450 mg per capsule.
Suggested use: 1 capsule, 2–3 times daily (per label).
Other ingredients: Hypromellose (cellulose capsule), rice flour, vegetable-source stearic acid.
Label claims: Non-GMO, Kosher, Vegan, Halal; free of dairy, egg, gluten, soy, and tree nuts.
Manufacturing: Produced in an NPA A-rated GMP-certified facility.
The most-cited trial here is Chandrasekhar et al. (2012, Indian Journal of Psychological Medicine): a randomized, double-blind, placebo-controlled study of 64 adults with chronic, self-reported stress. Participants took either a high-concentration, full-spectrum ashwagandha root extract at 300 mg twice daily (600 mg/day total) or a placebo, for 60 days. The ashwagandha group showed a significantly greater drop in stress-scale scores than placebo, and morning serum cortisol dropped by a statistically significant margin (p = 0.0006) compared with the placebo group. No serious adverse effects were reported in either arm.
In this one 60-day trial, a specific concentrated ashwagandha root extract measurably lowered both stress-scale scores and morning cortisol compared with placebo — in adults who described themselves as chronically stressed, not a general population, and not as treatment for a diagnosed condition.
Langade et al. (2019, Cureus) ran a 10-week randomized, double-blind, placebo-controlled trial using 600 mg/day of a standardized root extract (5% withanolides) in adults, including a subgroup formally diagnosed with a clinical sleep difficulty. Compared with placebo, the ashwagandha group showed statistically significant improvement (p < 0.002) in sleep-onset time, sleep efficiency, and total Pittsburgh Sleep Quality Index score — with the size of the improvement larger in the diagnosed-sleep-difficulty subgroup than in the healthy-sleeper group.
Neither trial above tested this NOW Foods product. Both used other standardized ashwagandha root extracts, at specific doses, and neither extract was described as a root-and-leaf blend like NOW's. Withanolide percentage, extraction method, and root-versus-leaf sourcing all affect what's actually in a capsule, so two labels that both say "ashwagandha extract, standardized" aren't automatically the same ingredient at the same strength. NOW's capsule is standardized to a comparable withanolide percentage (2.5%) and its labeled dose range (900–1,350 mg/day across 2–3 capsules) sits in a similar ballpark to the 600 mg/day used in both trials — but it is not the specific patented extract used in either published study, and no clinical trial has tested this exact product.
NOW Foods manufactures this product in its own NPA A-rated GMP-certified facilities, which covers the manufacturing process, lab testing methods, and formulation records. The finished product carries Non-GMO, Kosher, Vegan, and Halal claims on the label. That's a real, verifiable manufacturing-quality bar — but it's a facility- and process-level certification, not a clinical-efficacy certification, and it isn't the same thing as a third-party banned-substance screening (like NSF Certified for Sport) or a compound-specific identity-and-purity seal (like USP Verified). This product doesn't carry either of those, and buyers who specifically need one shouldn't assume it's included.
Ashwagandha can influence thyroid hormone levels, so the label directs anyone with a thyroid condition, or anyone taking thyroid medication, to talk to a physician first. The label also advises against use during pregnancy or while nursing, and flags that people with liver conditions or gastrointestinal sensitivity should check with a doctor before starting it, since mild digestive upset has been reported. None of this replaces an actual conversation with a healthcare provider — especially for anyone already taking a prescription medication.
The strongest research on ashwagandha and stress/cortisol, and on ashwagandha and sleep quality, is genuinely encouraging for specific standardized extracts used at specific doses over a defined number of weeks — not for a single capsule, and not overnight. NOW's version is a legitimately GMP-manufactured, clearly labeled, comparably standardized extract at a reasonable price point, but it isn't the exact extract used in the trials above. Anyone trying it for stress or sleep support should follow the label's own dosing guidance, expect to give it several weeks, and check with a doctor first if pregnant, nursing, on thyroid medication, or managing an existing health condition.
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This entry is not medical advice and is not intended to diagnose, treat, cure, or prevent any disease, including any diagnosed anxiety or sleep disorder. Ashwagandha may interact with thyroid, sedative, or immunosuppressant medications — talk to a healthcare provider before starting it, especially if pregnant, nursing, or managing an existing condition. This page contains an Amazon affiliate link; see our Disclosure page for how that works. These statements have not been evaluated by the Food and Drug Administration.
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.
Langade D, Kanchi S, Salve J, Debnath K, Ambegaokar D. "Efficacy and Safety of Ashwagandha (Withania somnifera) Root Extract in Insomnia and Anxiety: A Double-blind, Randomized, Placebo-controlled Study." Cureus, 2019.
NOW Foods — product label, Supplement Facts panel, and manufacturer specifications for Ashwagandha 450 mg Veg Capsules (accessed 2026-09).