Kava is consumed in various ways throughout the Pacific Ocean cultures of Polynesia, Vanuatu, Melanesia and some parts of Micronesia and Australia. Traditionally, it is prepared by either chewing, grinding or pounding the roots of the kava plant. Grinding is done by hand against a cone-shaped block of dead coral; the hand forms a mortar and the coral a pestle. The ground root/bark is combined with only a little water, as the fresh root releases moisture during grinding. Pounding is done in a large stone with a small log. The product is then added to cold water and consumed as quickly as possible.
The extract is an emulsion of kavalactone droplets in starch. The taste is slightly pungent, while the distinctive aroma depends on whether it was prepared from dry or fresh plant, and on the variety. The colour is grey to tan to opaque greenish.
Kava prepared as described above is much more potent than processed kava. Chewing produces the strongest effect because it produces the finest particles. Fresh, undried kava produces a stronger beverage than dry kava. The strength also depends on the species and techniques of cultivation. Many find mixing powdered kava with hot water makes the drink stronger.
In Vanuatu, a strong kava drink is normally followed by a hot meal or tea. The meal traditionally follows some time after the drink so the psychoactives are absorbed into the bloodstream quicker. Traditionally, no flavoring is added.
In Papua New Guinea, the locals in Madang province refer to their kava as waild koniak ("wild cognac" in English).
Fijians commonly share a drink called grog made by pounding sun-dried kava root into a fine powder, straining and mixing it with cold water. Traditionally, grog is drunk from the shorn half-shell of a coconut, called a bilo. Grog is very popular in Fiji, especially among young men, and often brings people together for storytelling and socializing. Drinking grog for a few hours brings a numbing and relaxing effect to the drinker; grog also numbs the tongue and grog drinking typically is followed by a "chaser" or sweet or spicy snack to follow a bilo.
The kava beverage is usually made from kava root powder. The root is dried and then finely ground into powder before being exported. Generally, one tablespoon of powder is added per cup of water, but sometimes as much as a half a cup of powder (eight tablespoons) is added per cup of water to increase potency. The powder is then soaked in water for about 30 minutes to allow the water to completely soak through the powdered fibers. Lecithin is often added to aid in the process of emulsifying the kavalactones with water. The kava powder, water, and lecithin are blended in a blender for several minutes then strained into a straining cloth. Nylon, cheesecloth, and silk screen are common materials for straining. The remaining liquid is squeezed from the pulp and the rest is discarded. As an alternative to the blender method, with the powdered pulp enclosed within the straining material, the pulp is massaged for five to 30 minutes in water, then the liquid is wrung out. As more pressure is applied to the wet powdered pulp while wringing it out, more kavalactones will be released from it. Finally, the pulp resin is discarded and the beverage is enjoyed. Often, coconut water, coconut milk, lemongrass, cocoa, sugar, or soy milk is added to improve flavor.
Kava is chewed by some to relieve symptoms of throat pain, as it produces a "numbing" effect on the tongue and throat. The kava is first chewed in the back of the mouth for five to 10 minutes while swallowing the saliva and kavalactones released from the process. It produces an effect similar to that of Chloraseptic spray (an over-the-counter medicine to alleviate sore throat by numbing it, via pump-spraying it into the mouth).
Kava's active principal ingredients are the kavalactones, of which at least 15 have been identified and are all considered psychoactive. Only six of them produce noticeable effects, and their concentrations in kava plants vary. Different ratios can produce different effects.
Effects of kavalactones include mild sedation, a slight numbing of the gums and mouth, and vivid dreams. Kava has been reported to improve cognitive performance and promote a cheerful mood. Kava has similar effects to benzodiazepine medications, including muscle relaxant, anaesthetic, anticonvulsive and anxiolytic effects. They are thought to result from direct interactions of kavalactones with voltage-gated ion channels. Research currently suggests kavalactones potentiate GABAA activity, but do not alter levels of dopamine and serotonin in the CNS. It is thought to do this via modulating GABA activity via altering the lipid membrane structure and sodium channel function.
Desmethoxyyangonin, one of the six major kavalactones, is a reversible MAO-B inhibitor (Ki 280 nM) and is able to increase dopamine levels in the nucleus accumbens. This finding might correspond to the slightly euphoric action of kava.
Kavain, in both enantiomeric forms, inhibits the reuptake of noradrenalin at the transporter (NAT), but not of serotonin (SERT). An elevated extracellular noradrenalin level in the brain may account for the reported enhancement of attention and focus.
Medical literature sometimes claims kava has a "potential for addiction" because "it produces mild euphoria and relaxation". In a traditional setting, a moderately potent kava drink causes effects within 20–30 minutes that last for about two and a half hours, but can be felt for up to eight hours. Some report longer-term effects up to two days after ingestion, including a feeling of mental clarity, patience, and an ease of acceptance. The effects of kava are most often compared to alcohol, or diazepam.
The sensations, in order of appearance, are slight tongue and lip numbing (the lips and skin surrounding may appear unusually pale), mildly talkative and sociable behavior, clear thinking, calmness, relaxed muscles, and a sense of well-being. As with other drugs that affect the GABA receptors, there can also be paradoxical dysphoria. The numbing of the mouth is caused by the two kavalactones kavain and dihydrokavain, which cause the contraction of the blood vessels in these areas, acting as a local topical anesthetic. These anesthetics can also make one's stomach feel numb. Sometimes, this feeling has been perceived as nausea.
The effects of a kava drink vary widely with the particular selection of kava plant(s) and amount. A potent drink results in a faster onset with a lack of stimulation; the user's eyes become more sensitive, the person soon becomes somnolent and then has deep, dreamless sleep within 30 minutes. Sleep is often restful and pronounced periods of sleepiness correlate to the amount and potency of kava consumed. Kava drinkers are often perceived as having lazy days after consumption of kava the night before, which can be expected as many active kavalactones have half lives of approximately 9 hours. Although heavy doses can cause deep, dreamless sleep, many people reportedly experience lighter sleep and rather vivid dreams after drinking moderate amounts of kava.