Verdict
Not enough evidence
300 to 600 mg of standardized ashwagandha extract a day lowers cortisol.
1 source: 1 partly
By Arun AgrahriLast reviewed 3 timecoded sources
Short answer
300mg twice daily (600mg total) of a standardized extract is the dose on the record for lowering cortisol. Most standardized-extract studies use 300-600mg/day. Andrew Huberman cycles off after about 30 days and checks bloodwork. Start at 300mg to assess tolerance.
Ashwagandha is worth taking.
The verdict on Ashwagandha overall. 6 sources: 3 positive, 3 partly
positive partly neutral negative Each researcher and each study counts once per claim, however often they come up.
300 to 600 mg of standardized ashwagandha extract a day lowers cortisol.
1 source: 1 partly. Fewer than 3 sources so far.
Researchers say
1 partly
Bryan Johnson, on Bryan Johnson's channel, at 01:47
Partly Video · Opinion
Open the tape at 01:47 →“this is ashwagandha, it helps with anti-anxiety, improved cortisol management, improve sleep, and increase testosterone. 600 milligrams once a day.”
Studies show
No study counted yet.
Bryan Johnson, on Bryan Johnson's channel, at 01:47 Video · partly · Opinion
“this is ashwagandha, it helps with anti-anxiety, improved cortisol management, improve sleep, and increase testosterone. 600 milligrams once a day.”
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The dose on the record is 300mg twice daily, 600mg a day in total, of a standardized extract. Every source that names a number lands in that range, and most clinical studies use 300-600mg/day of a standardized root extract.
Andrew Huberman, on his own show, recommends that dose of a standardized extract to lower cortisol, across 8 videos. He takes it in the evening, paired with apigenin for cortisol. He is also the one source with a cycling rule: come off after about 30 days and check bloodwork.
Peter Attia takes 600mg at night, alongside 2g of glycine and magnesium L-threonate, with no cycling rule. Bryan Johnson takes it once a day in his morning stack. It also turns up as an adaptogen for adrenal support and stress resilience, often paired with rhodiola, magnesium and B vitamins.
No source picks KSM-66 over Sensoril; both count as standardized extracts. A practical protocol: start at 300mg once daily to check tolerance, and move to 300mg twice daily if you need it. Take it in the evening for cortisol and sleep, or in the morning for daytime stress. Cycle off after about a month.
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