Ashwagandha for Stress and Cortisol: What the Research Shows

Most of the stronger clinical evidence for ashwagandha uses a standardized, concentrated root extract at a specific milligram dose, not the same as raw ashwagandha powder measured in grams. A product listing "ashwagandha" without specifying whether it's a standardized extract (and at what strength) or a raw powder makes it hard to compare against the research doses above. This is exactly the kind of specificity gap our Nagano Lean Body Tonic review flags, its label names ashwagandha inside a proprietary blend without disclosing the form or amount.

Thyroid function: a randomized, placebo-controlled trial in people with subclinical hypothyroidism found 600mg/day of ashwagandha root extract over 8 weeks significantly improved TSH, T3 and T4 levels compared to placebo (Sharma et al., 2018). That's a genuine effect on thyroid hormone levels, not a theoretical caution: anyone on thyroid medication, or with a diagnosed thyroid condition, should talk to their doctor before taking ashwagandha regularly, since a supplement that measurably shifts TSH/T3/T4 can interact with dosing for an existing thyroid prescription. See the NIH ODS ashwagandha fact sheet for the fuller evidence and safety summary.

Sedative and interacting medications: ashwagandha has a mild sedative profile in some studies, which means combining it with other sedatives, sleep medication, or alcohol may have an additive effect. It's also generally advised against during pregnancy, based on traditional use data and a lack of robust human safety trials in pregnancy specifically.

Ashwagandha has real, if modest, RCT-level support for stress and cortisol reduction: a genuine point in its favor as an ingredient category. As with every ingredient in Nagano's proprietary blends, our Nagano review can't confirm the actual dose or extract form used, so the strength of the evidence above is a ceiling on what's plausible, not a guarantee of what the product delivers.