Kava is made from the root and rhizome (underground stem) of a tropical shrub called Piper methysticum, a member of the pepper family. The thick, starchy rootstock is harvested, processed, and mixed with water to create a muddy, earthy-tasting beverage that has been central to Pacific Island cultures for centuries. Only the root is used in traditional preparations, and that distinction matters more than most people realize.
The Plant Itself
Piper methysticum is a leafy shrub that grows across Polynesia, Melanesia, and Micronesia. It thrives in tropical climates and is cultivated specifically for its rootstock, which grows into a dense, knotted mass underground over several years. A mature kava plant is typically harvested after three to five years of growth, when the root system has accumulated enough of the compounds that give the drink its effects.
The plant produces leaves and stems, but these parts are not traditionally consumed and contain a different chemical profile than the root. A compound called pipermethystine, found primarily in the leaves and stem peelings, has been shown to be toxic to liver cells in laboratory studies. The six major active compounds in the root, by contrast, are not mutagenic. This is why traditional Pacific Island preparation has always focused exclusively on the root.
What’s in the Root
The root contains a group of compounds called kavalactones, which are responsible for kava’s calming, mildly euphoric effects. Researchers have isolated 18 different kavalactones from the plant, but six account for most of the activity: kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin. The specific ratio of these six compounds varies between kava varieties, and that ratio shapes the experience.
Not all kava plants are the same. “Noble” varieties have a more balanced distribution of kavalactones, producing a gentler, shorter-lasting effect. “Tudei” (two-day) varieties contain higher concentrations of dihydrokavain and methysticin, making them stronger and longer-lasting but also more likely to cause nausea and grogginess. Most reputable kava sellers stick to noble cultivars.
How Kavalactones Work in the Body
Kavalactones enhance the activity of GABA receptors in the brain. GABA is the nervous system’s main calming signal, and when kavalactones boost its effect, the result is reduced anxiety, mild muscle relaxation, and a sense of well-being. A 2016 study published in PLoS One provided the first direct evidence that kavain, the most abundant kavalactone, physically binds to GABA receptors and amplifies their response. Interestingly, kavain works through a different binding site than common anti-anxiety medications like benzodiazepines, which means it produces relaxation through a related but distinct mechanism.
Traditional Preparation
The traditional method is straightforward. Fresh or dried kava root is ground into a coarse powder, placed in a cloth strainer bag, and submerged in water. The mixture is kneaded by hand for about five minutes, squeezing and wringing the bag repeatedly to draw the kavalactones out of the root fibers and into the water. The result is a cloudy, brownish liquid with a peppery, slightly numbing taste. A typical serving uses about 30 to 35 grams of root powder in roughly 500 milliliters of water.
Kavalactones are not highly water-soluble, which is why kneading is essential. The physical agitation helps suspend the active compounds in the liquid. Some preparations add a small amount of coconut milk or oil, since kavalactones dissolve more readily in fat. After the first extraction, many people do a “second wash” by adding more water and kneading again to pull out remaining compounds, though this produces a weaker drink.
The drink is traditionally consumed in a single sitting, swallowed in one or two quick gulps from a coconut shell or small cup. Fruit is often eaten afterward to cleanse the palate.
Modern Kava Products
Today, kava comes in several forms beyond the traditional grind. Micronized kava is root powder ground to an extremely fine consistency, with most of the coarse plant fiber filtered out. You stir it directly into water or another liquid without needing a strainer bag. It’s convenient, though trace fiber remains and gives the drink a slightly gritty texture.
Instant kava takes a different approach entirely. Fresh kava roots are juiced, and that liquid is then dehydrated into a powder. Because the woody root fibers are strained out during juicing, the final product dissolves cleanly and has a noticeably smoother mouthfeel. Instant kava is the most processed form but also the easiest to prepare.
Kava is also sold as capsules, tinctures, and concentrated extracts. These use various solvents, including ethanol or acetone, to pull kavalactones from the root in higher concentrations than water-based preparation achieves. The chemical profile of these extracts can differ significantly from traditionally prepared kava, which is relevant to the safety discussion.
The Liver Safety Question
In 2002, the FDA issued a consumer advisory warning that kava-containing dietary supplements may be associated with severe liver injury. The agency cited over 25 reports of liver-related problems in other countries, including hepatitis, cirrhosis, and liver failure, plus at least one case in the U.S. where a previously healthy young woman required a liver transplant.
The cause of these liver injuries remains debated. Several factors may have contributed: the use of leaves and stems (which contain the toxic compound pipermethystine) rather than root alone, extraction with organic solvents that pull different compounds than water does, the use of tudei rather than noble varieties, and interactions with alcohol or medications. Traditional water-based preparation of noble kava root has a long safety record in Pacific Island communities, where it has been consumed regularly for generations. The distinction between what’s in a traditional bowl of kava and what’s in a commercially produced extract capsule is meaningful, and the raw ingredients involved are not always the same.