The kava-lactones, sometimes referred to as kava-pyrones, are the most important active constituents in kava extracts. High-quality kava rhizome contains 5.5–8.3% kava-lactones.¹ Medicinal extracts used in Europe contain 30–70% kava-lactones. Kava-lactones are thought to have anti-anxiety, mild analgesic (pain-relieving), muscle-relaxing, and anticonvulsant effects.^{2, 3} Some researchers speculate that kava may directly influence the limbic system, the ancient part of the brain associated with emotions and other brain activities.⁴ Kava is a unique anti-anxiety alternative because it does not seem to impair reaction time or alertness when used in the amounts recommended below.⁵

Kava has been extensively studied as a treatment for anxiety.⁶ The amount often used in clinical trials is 100 mg of an extract (standardized to 70% kava-lactones) three times per day. Double-blind trials, including one that lasted six months, have shown that kava effectively reduces symptoms of anxiety in people with mild to moderate anxiety.^{7, 8} One trial found that kava also reduced symptoms of anxiety in menopausal women,⁹ and in another study kava enhanced the anti-anxiety effect of hormone replacement therapy.¹⁰ One trial found kava to be just as effective as benzodiazepines (a common class of drugs prescribed for anxiety) in treating mild anxiety over the course of six weeks.¹¹