Power plant? What new research reveals about kava

Marc Wilson

Psychology writer·New Zealand Listener·

18 May, 2026 06:06 PM4 mins to read

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In Fiji and Tonga, the sun-dried roots are ground, mixed and strained into a tanoa (a wooden bowl) then served in cups made of coconut shells. Photo / Getty Images

I’m in Rarotonga, celebrating our 25th wedding anniversary with our adult children and their partners. The boy is checking in on the rabbit using the online camera. I’m thinking about what to make for lunch. Oh, and what to do today.

We’ve discovered many cultural ceremonies aren’t on during
our visit because there’s a big competition happening. But that doesn’t mean there’s no opportunity to try something different. For example, kava. We hadn’t been here an hour before the lad had sourced some for a, ahem, poolside ceremony of his own.

Kava is derived from the plant piper methysticum, colloquially called kava kava. I didn’t know it’s part of the same family of plants that includes piper nigrum, which you’ll know as the source of the black pepper in our pantry cupboards. Piper methysticum is an evergeen shrub that can grow as high as 7m, with large, heart-shaped leaves that apparently look a lot like our own native kawakawa. Hmm, kava kava, kawakawa (though it’s actually piper excelsum, endemic to New Zealand).

The Pacific cousin is valued for the kavalactones most highly concentrated in the roots. The experience of ingesting kava (“being rooted”) is often described as inducing a profound, calm and grounded relaxation without the mental fogginess or loss of control associated with alcohol.

Since the 1990s, kava has been promoted for a range of uses, including as a treatment for stress and anxiety. It also has relaxant and anticonvulsant effects, and acts as a mild sedative and analgesic. Unlike some of the hype around other “natural” products, a Cochrane review (the gold-standard analysis of findings from previous studies) found kava significantly better than a placebo for managing anxiety in the short term. It’s been proposed as a culturally appropriate component for treatment of post-trauma symptoms, and appears to be as effective as prescribed drug treatments for mild-to-moderate anxiety in the short term, but without the same side effects.

You can prepare kava for use from dried or fresh roots, but you can buy the dry ground product, legally, in stores in many parts of the Pacific. Preparation and rituals vary around the region: in Fiji and Tonga, the sun-dried roots are ground, mixed and strained into a tanoa (a wooden bowl) then served in cups made of coconut shells. In Samoa, the fresh roots are often mashed into a pulp, then mixed in a tanoa and served by the ‘aumanga – young men yet to gain a title – and served to chiefs and guests. This is often highly ritualised and serves to develop and maintain community.

Apparently, the kava tastes quite bitter and peppery on first try, particularly when made from dried powder, and is followed by an earthy aftertaste accompanied by a numbing of the mouth similar to what you get when the dentist sticks you with an anaesthetic.

Though it may not have the side effects of benzodiazepines, it does have side effects, including short-term sedation, headache, dizziness and nausea, and the abovementioned mouth numbness. It can also trigger liver damage.

The evidence for cognitive impairment is somewhat mixed. A recent study by University of Waikato and ESR researchers evaluated the cognitive effects of kava at the start, middle and end of a six-hour faikava session. The session follows a traditional protocol, including talanoa (a Pacific form of discussion), and consumption of fruit, peanuts, chips and sweets (called “chasers”). In a traditional session, participants drink about 31/2 litres of kava.

This study found no negative impacts on cognitive speed or accuracy, perception of time, ability to respond to what’s going on around you, or focus. But keeping track of the order of events was affected, and the authors speculate this would be particularly problematic if users drove home after the ceremony. Don’t kava and drive, then. Or fly, in our case.

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