Kavalactones are chemical compounds found within the kava plant, Piper methysticum. These substances are largely responsible for the plant’s psychoactive properties. Kavalactones interact with the body to produce effects recognized and utilized for centuries in Pacific Island cultures.
The Source and Chemistry of Kavalactones
The kava plant, Piper methysticum, is the sole natural source of kavalactones. These compounds are primarily concentrated in the plant’s roots and rhizomes, which are the underground stems. Kavalactone is a class comprising at least 18 distinct but related compounds.
Six kavalactones are considered most significant due to their abundance and contribution to kava’s effects: methysticin, dihydromethysticin, kavain, dihydrokavain, yangonin, and desmethoxyyangonin. The specific profile and ratio of these kavalactones within a kava plant determine its “chemotype.” This chemotype is often represented as a six-digit number, indicating the descending order of the most prevalent kavalactones. Various factors, including the plant’s age, geographical origin, and specific part used, can influence its kavalactone content and chemotype.
Neurological and Physiological Impact
Kavalactones influence the central nervous system after crossing the blood-brain barrier. A primary mechanism involves their modulation of gamma-aminobutyric acid (GABA) receptors, particularly GABA-A receptors, which are inhibitory neurotransmitters. This interaction enhances GABAergic activity, contributing to relaxation and reduced anxious states.
Kavalactones also appear to block voltage-gated sodium and calcium ion channels, which can lead to a numbing sensation and muscle relaxation. There is also evidence suggesting their influence on dopamine and serotonin levels, though the exact nature of these interactions can vary depending on the specific kavalactone and dosage. Additionally, some kavalactones may reversibly inhibit monoamine oxidase B (MAO-B) and show affinity for cannabinoid type-1 (CB1) receptors. These diverse actions collectively contribute to the anxiolytic, mild sedative, and muscle relaxant properties of kava.
Forms of Consumption and Potency Variation
Traditionally, kava is prepared by grinding or pounding the Piper methysticum root and steeping it in water, sometimes with fats like coconut milk to enhance extraction. This yields a non-alcoholic beverage with varying kavalactone concentrations. The potency of traditional preparations can differ significantly based on the kava cultivar used and the meticulousness of the preparation.
In modern contexts, kava is available in various commercial forms, including capsules, tinctures, and instant powders. These modern preparations often utilize solvent extraction methods, such as with acetone or ethanol, which can yield a higher concentration of kavalactones compared to water-based traditional preparations. The extraction solvent and method of preparation directly influence the kavalactone profile and the overall potency of the final product.
Health Considerations and Risks
A significant health consideration with kava consumption is the potential for hepatotoxicity, or liver damage. While the exact mechanisms are still debated, case reports have linked kava products to severe liver injuries, including hepatitis, cirrhosis, and liver failure, with some cases necessitating liver transplantation. Some research suggests that these risks may be elevated with certain kava preparations, such as those made from leaves and stems rather than only the root, or when co-consumed with alcohol.
Beyond liver concerns, other potential side effects include drowsiness, impaired motor skills, and gastrointestinal upset such as nausea or stomach pain. Long-term, heavy consumption of kava may also lead to a distinctive skin condition known as kava dermopathy, characterized by dry, scaly skin. It is advised to avoid consuming kava with alcohol or other central nervous system depressants due to increased risk of adverse effects.