Kava

Plant Part Used

Root/Rhizome

Active Constituents

Unique kavalactones/kavapyrones (dihydrokavain, kavain, methysticin, dihydromethysticin, yangonin, others).(1)

[span class=alert]This section is a list of chemical entities identified in this dietary supplement to possess pharmacological activity. This list does not imply that other, yet unidentified, constituents do not influence the pharmacological activity of this dietary supplement nor does it imply that any one constituent possesses greater influence on the overall pharmacological effect of this dietary supplement.[/span]

Introduction

Kava has been used for centuries by South Pacific natives. The root is traditionally used in the preparation of a recreational beverage known by a variety of local names (kava, yaqona, awa) and occupies a prominent position in the social, ceremonial, and daily life of Pacific island peoples as coffee or tea does in the Western cultures. In European phytomedicine, kava has long been used as a safe, effective treatment for mild anxiety states, nervous tension, muscular tension, and mild insomnia. It has even been used therapeutically in Germany for gonorrhea and may be of interest in the supportive management of drug addiction and withdrawal.(2) Kava products are under intense scrutiny in many Countries after case reports of hepatotoxicity and acute hepatic failure. See Advisory Warning in General Toxicity /Precaution sections of this monograph.

Interactions and Depletions

Interactions

Kava has been reported in laboratory studies to inhibit CYP2E1 hepatic enzyme system and P-glycoprotein, both involved in drug metabolism.(38)

Dosage Info

Dosage Range

100-3000mg (standardized extract), 1-3 times a day for anxiety; single dose of 250-300mg (standardized extract) one hour before bedtime for insomnia.

 

Tincture: 30 drops with water 3 times daily.(3)

Infusion: Use 5-10gm dried herb; steep in one cup hot water (240ml) for 10-15 minutes; strain and drink ½ cup twice daily.(3)

Most Common Dosage

100mg (standardized extract), 3 times a day as needed for anxiety; 250mg (standardized extract) one hour before bedtime for insomnia.

Tincture: 30 drops with water 3 times daily.

Infusion: Use 5-10gm dried herb; steep in one cup hot water (240ml) for 10-15 minutes; strain and drink ½ cup twice daily.

Standardization

[span class=doc]Standardization represents the complete body of information and controls that serve to enhance the batch to batch consistency of a botanical product, including but not limited to the presence of a marker compound at a defined level or within a defined range.[/span]

The most current available medical and scientific literature indicates that this dietary supplement should be standardized to 30-70% kavalactones.

Uses

Frequently Reported Uses

  • Stress/Antianxiety Agent
  • Increase Concentration, Mental Function
  • Menopausal Nervousness

Other Reported Uses

  • Analgesic
  • Antifungal
  • Skeletal Muscle Relaxant
  • Insomnia, Especially Due To Stress
  • Cystitis
  • Opiate Addiction

Toxicities & Precautions

General

Note: Although used for decades in Europe with success in treating anxiety, kava is controlled or banned in many Countries due to cases of hepatotoxicity and acute hepatic failure.(4) As of 2010, there have been 26 reported cases of hepatotoxicity in humans, some resulting in liver transplants.(41)  Below is a summary of the Legal Status of Kava supplements (ca.2010)

  • The possibility of liver damage consequently prompted action of many regulatory agencies in European countries where the legal precautionary principle so mandated.
  • In the UK, the Medicines for Human Use (Kava-kava) (Prohibition) Order 2002 prohibits the sale, supply or import of most derivative medicinal products. According to the Medicines Control Agency in the U.K., there is no safe dose of kava, as there is no way to predict which individuals would have adverse reactions.
  • Kava is banned in France and the Netherlands.
  • In Switzerland, the pharmaceutical Kava product Laitan is banned.
  • The health agency of Canada issued a stop-sale order for kava in 2002. But legislation in 2004 made the legal status of kava murky to many, especially since not everyone is aware that a stop-sale order does not constitute a ban such as that applies in several European countries. Kava is neither illegal nor legally banned in Canada, nor is it regulated and it does not fall under any of the Food and Drugs Act & Regulations.
  • On March 25, 2002, the Food and Drug Administration (FDA) issued an advisory notifying consumer that kava-containing dietary supplements may be associated with severe liver injury. The FDA reported that kava-containing products have been associated with liver-related injuries, including hepatitis, cirrhosis, and liver failure, in over 25 reports of adverse events in other countries. In the U.S., FDA received a report of a previously healthy young female who required liver transplantation, as well as several reports of liver-related injuries.
  • In Australia, the supply of kava is regulated through the National Code of Kava Management. The sale and supply of kava is prohibited in Western Australia and the Northern territory. The Australian Therapeutic Goods Administration has recommended that no more than 250 mg of kavalactones be taken in a 24 hour period.

In a case report, a 50 year old man presented with jaundice and had noticed fatigue for a month and a "tanned" skin, and dark urine.(7) He had been consuming three to four capsules of a European kava product daily for two months (maximum recommended dose three capsules) corresponding to a dose of 210-280 mg lactones. He took no other drugs and did not consume alcohol. Liver function tests showed a 60-fold and 70-fold increase in aspartate aminotransferase and alanine aminotransferase concentrations, respectively. Alkaline phosphatase, 7-glutamyltransferase, lactate dehydrogenase and total and conjugated bilirubin levels were also significantly elevated. After admission to a hospital, he developed stage IV encephalopathy, subsequently receiving a liver transplant two days later and recovered. Heavy consumption of kava has been associated with increased concentrations of 7-glutamyltransferase, along with a case of recurring necrotizing hepatitis being reported.(28),(29) A cross-sectional study with 98 participants found that moderate consumption of kava may cause changes in liver function. After 1-2 weeks of abstinence of kava, liver damage appeared to be reversible and started to return to baseline.(30) Methanolic extracts of kava root and kava leaf independently were reported in an in vitro study to produce mitochondrial toxicity, leading to inhibition of the respiratory chain, increased ROS production, a decrease in the mitochondrial membrane potential and eventually to apoptosis of exposed hepatic cells.(42)

In a 2009 study by the University of Queensland, Australia, researchers found that the study's participants did not show any signs of potential liver damage, contrary to concerns that prompted European, British and Canadian authorities to ban kava sales in 2002.(43) A review of kava-induced hepatoxicity in 14 patients found that hepatic effects of kava products occurred independently whether aqueous, ethanolic and acetonic kava extracts or kava-herbs mixtures were used.(44)  A small human study in 31 heavy kava users of traditional kava beverage compared to non-kava users found that Heavy kava beverage consumption was associated with significantly elevated GGT levels.(45)

Use with caution when driving an automobile or operating heavy machinery.(5) According to the German Commission E, it is recommended to use kava for no more than 3 months unless under the supervision of a physician.

Health Conditions

Based on pharmacology, kava should not be recommended to people with Parkinson’s.(6) Also, kava should not be used in individuals with symptoms of gall bladder or liver problems including cirrhosis, hepatic viral infections, among other hepatobilliary diseases.(7) Use with caution in individuals taking prescription and non-prescription medications that may place stress on hepatic function.

Side Effects

With large consumption (doses 10 times recommended), such as in tea form, the potential for kava dermopathy may result.(8),(9) Symptoms disappear if discontinued or if dosages are reduced.

Pregnancy/ Breast Feeding

Based on pharmacology, do not use in pregnancy.(10)

Age Limitations

Do not use in children under 2 years of age unless recommended by a physician.

Pharmacology

Kava preparations have been used for decades in European countries for the treatment of nervous anxiety and restlessness.(11),(12),(46) Studies have reported that kava preparations compare favorably to benzodiazepines in controlling symptoms of anxiety and minor depression, while increasing vigilance, sociability, memory, and reaction time.(13),(14) Reports are conflicting as to whether kava’s anti-anxiety actions are GABA mediated.(15),(16) In one in vitro study, kava’s GABA activity was not based upon an interaction of the kavapyrones with the benzodiazepine receptor.(17) Kavalactones also appear to act on the limbic system, in particular the amygdala complex – the primitive part of the brain that is the center of the emotional being and basic survival functions.(18) It is thought that kava may promote relaxation, sleep, and rest by altering the way in which the limbic system modulates emotional processes. Results of one in vitro study reported that kava seems to produce a pyrone-specific non-stereo-selective inhibition of the [3H]-noradrenaline which may be responsible for, in part, the psychotropic properties of kava pyrones.(19)

Using the Hamilton-Anxiety Scale, a double-blind study reported that a standardized kava preparation had a statistically significant reduction in symptoms of anxiety including feelings of nervousness and somatic complaints such as heart palpitations, chest pains, headache, dizziness, and feelings of gastric irritation.(21) A meta-analysis reported that kava was an effective agent for the symptomatic treatment of anxiety. Double-blind, randomized, placebo-controlled trials of oral kava extract for the treatment of anxiety were included. Superiority of kava extract over placebo was suggested by all seven reviewed trials.(22) Researchers suggest after a multicenter, randomized, placebo-controlled, double-blind clinical trial that kava may be effective and safe when used for sleep disturbances associated with anxiety disorders.(23)

In one study, fifty-two outpatients suffering from anxiety of nonpsychotic origin were under observation while taking a kava supplement.(24) 81% of the individuals taking the kava preparation rated the treatment as "very good" or "good." The authors concluded that the results supported this kava supplement as an effective and safe alternative to antidepressants and tranquilizers in anxiety disorder without the tolerance problems associated with benzodiazepines.

Several other studies have reported positive effects of kava supplements in women’s health issues, especially when anxiety is present (including in PMS and menopausal complaints).(2),(25) One study of kava supplementation in forty menopausal women taking hormonal replacement therapy (HRT; topical estrogen/progestin) or placebo and also presenting with anxiety was performed.(26) The women were divided into groups – those with physiological or surgical menopause for the past 1 to 12 years. After 3-6 months of therapy, a significant reduction in the HAMA score in all four groups of women studied. A greater reduction in the anxiety scores was reported in the groups treated with the HRT and kava, than patients treated with the hormones alone or with hormones and placebo. Another placebo-controlled study of 20 women with acute anxiety while waiting for the results of their mammography reported that a kava preparation reduced the situational anxiety, along with a significant increase in alertness and a lessening of fatigue, introverted behavior and excitability as well as a reduction in levels of depression.(27)

Other Uses

Sleep studies have reported that kava enhances the sleep spindle density, reducing sleep latency, and increasing slow-wave sleep without changes to REM sleep.(20)

Kava has been reported in laboratory studies to have anti-inflammatory activity, inhibiting the inflammatory cytokines NF-kappaB and TNF-alpha.(47),(48) Kava preparations have also been reported to produce skeletal muscle relaxation (comparable to mephenesin),(31) have anticonvulsant activity,(32) produce local anesthetic action on mucous membranes along with analgesia,(33) be antifungal (not for Candida)(34) and have beneficial effects in relieving temporary, transient insomnia.(18)

Kava is commonly used in a proprietary formula in Europe for treating cystitis and dysuria. It also is claimed to reduce pain, but does so in a manner different from opioids or nonsteroidal anti-inflammatory drugs (NSAIDs).(35) Kava is claimed to help protect the brain against ischemic episodes, though this needs further study.(36) Tolerance does not seem to develop with kava use. (12),(37)

References

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