Kava, a nutritional supplement, remains available in the U.S. despite safety concerns, according to a 2011 report in "Digestive and Liver Disease." Manufacturers use the leaves, stems and roots of Piper methysticum to make kava. That plant grows in the western Pacific islands. Traditional healers used kava as a relaxant. Modern researchers have found evidence supporting this use. Other applications have been developed as well. Kava can damage the kidneys, so consult a physician before taking it.
Relieves Anxiety
The Piper methysticum plant played an important role in Tongan society. It was used as an alternative to alcohol. It was a way to stimulate conversation and bonding, according to a 2009 review in "Pacific Health Dialog." This social use may translate into a clinical application. A 2011 article published in "Psychopharmacology" reported on research that tested the potential use of Piper in anxiety disorders. Patients received daily doses of kava or placebo for three weeks. They then received the opposite treatment for three weeks. Relative to placebo, Piper reduced anxiety and improved depression without causing side effects. While effective in patients with severe anxiety, no study has evaluated the effect of kava in other forms of anxiety.
Improves Performance
According to a 2010 study in "Experimental and Clinical Psychopharmacology," most anti-anxiety drugs reduce daytime performance and alertness. They also cause unwanted reactions such as tolerance and withdrawal. Piper methysticum, in contrast, appears to calm people without sedation. It may also have a better safety profile. A 2004 report presented in "Human Psychopharmacology" looked at the impact of Piper on human behavior. Healthy subjects received either kava or placebo during a single testing session. The supplement, relative to placebo, improved accuracy and speed on performance tasks. Subjective ratings indicated that it had a positive effect on mood as well. The volunteers did not experience any untoward reactions, but the long-term effects of kava remain unknown.
Promotes Sleep
Medications which reduce anxiety often facilitate sleep. Consistent with this finding, Piper methysticum magnifies the effects of other sedatives, according to a 2005 report in "Phytomedicine." This finding suggests that kava may affect sleep. A 2005 paper offered in "Psychopharmacology" tested this idea. Rodents received the kava extract, a sleeping pill or an inert treatment during a single testing session. Kava reduced the time it took for the rats to fall asleep, and it enhanced the amount of deep sleep they experienced. Larger effects, however, were achieved with the sleeping pill. The researchers did not observe any signs of toxicity. Yet, studies done with animals may produce different results from those done with humans.
Damages Cells
Several people have experienced toxic reactions from using kava, according to 2011 review in "Phytomedicine." The causes behind the kidney damage resulting from these reactions remain unknown. Contaminants such as mold were originally thought responsible for these untoward effects. Yet, chemicals contained within the Piper methysticum plant may contribute as well. A study described in the 2011 volume of "Phytotherapy Research" evaluated the toxicity of active ingredients isolated from Piper. The authors exposed human kidney cells to methysticin, yangonin and kavain. Yangonin, the most damaging substance, killed 40 percent of the kidney cells. The mechanisms underlying this damage remain unknown, but people should wait for more data before consuming kava.
References
- "Digestive and Liver Disease"; Herbal Hepatotoxicity by Kava: Update on Pipermethystine, Flavokavain B, and Mould Hepatotoxins as Primarily Assumed Culprits; Rolf Teschke, et al.; March 3, 2011
- "Pacific Health Dialog"; Social, Cultural and Medicinal Use of Kava for Twelve Tongan Born Men Living in Auckland, New Zealand; V. Nosa and M. Ofanoa; February 2009
- "Psychopharmacology"; Kava Anxiety Depression Spectrum Study (KADSS): A Randomized, Placebo-Controlled Crossover Trial Using an Aqueous Extract of Piper Methysticum; Jerome Sarris, et al.; Feb. 23, 2011
- "Experimental and Clinical Psychopharmacology"; Dose Effects of Triazolam and Alcohol on Cognitive Performance in Healthy Volunteers; Bethea A. Kleykamp, et al.; February 2010
- "Human Psychopharmacology"; Enhanced Cognitive Performance and Cheerful Mood by Standardized Extracts of Piper Methysticum (Kava-Kava); Richard Thompson, et al.; June 2004
- "Phytomedicine"; Pharmacological Studies on the Sedative and Hypnotic Effect of Kava Kava and Passiflora Extracts Combination; A. Capasso and L. Sorrentino; January 2005
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