What trials show for tongkat ali, ashwagandha, zinc and boron individually on testosterone and SHBG, the doses studies used, safety limits, and why the four have never been tested together.
Rhodiola rosea has randomized-trial evidence for stress-related fatigue and mental performance under pressure. The doses trials used, how it differs from ashwagandha, and safety.
Ashwagandha lowered cortisol and stress scores in placebo-controlled trials; sleep, testosterone and thyroid data are smaller. The trials worth knowing, the doses they used and who should avoid it.
Adaptogens are herbs said to help the body resist stress. Ashwagandha lowered stress and cortisol in a meta-analysis; rhodiola's evidence is thinner. Liver, thyroid, pregnancy and drug cautions.
CBD has one FDA-approved use — Epidiolex, for rare epilepsies — and much thinner evidence for anxiety, pain and sleep. What the trials show, where the law stands, and why drug interactions matter.
Kava beat placebo for anxiety symptoms in a Cochrane review, but the largest 16-week trial was negative. Rare liver injury is tied mostly to solvent extracts, non-root parts and alcohol.
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