Kava is the best studied herb for treating anxiety. Researchers searching for the active part of the plant have discovered that Kava contains chemicals known as kavalactones. In various research studies, kavalactones have demonstrated sedative (calming and relaxing), anxiolytic (anti-anxiety), analgesic (pain reducing), local anesthetic (numbing), and anticonvulsant (reduces muscle spasms) properties. These properties combine to make Kava ideal for use in treating anxiety.
Scientists are not certain about how Kava combats the body's anxiety response. Other anti-anxiety medications work by increasing the activity of a neurotransmitter (a chemical that conveys messages in the brain and nervous system) known as GABA (gamma-aminobutyric acid). GABA is thought to produce an upbeat mood, positive self-image, sense of calm/contentment, and sound sleep. People who experience anxiety often have low levels of GABA in their brains. Some studies have shown that kavalactones decrease anxiety by stimulating the activity of GABA; however, others studies have not found this result.
Common Side Effects of Kava
- Balance problems (dizziness)
- Mild stomach upset
- Morning fatigue
- Mouth numbness
- Skin rash
- Slow muscle reflexes
- Visual problems (problems focusing)
Another theory about Kava's mechanism of action suggest that kavalactones may cause a calcium ion channel blockade. Calcium ion channels are little tunnels across the membranes of nerve cells. Such channels are like border crossings; they exist to allow calcium to enter the nerve cells. A blockade of nerve cell ion channels has the effect of closing a gate across the channel, preventing calcium from entering the nerves. It is thought that partial blockade of calcium ion channels may cause a calming effect because nerve cells require calcium ions in order to fire, and blocking calcium from entering affected nerves thus may keep them from firing and causing symptoms of anxiety. Though this is an interesting theory, current research does not support this line of thinking.
Still another theory suggests that kavalactones act in a manner analogous to antidepressant medications. These medications work by increasing the total amount of specific neurotransmitters in the brain or by allowing existing neurotransmitters to stay at work longer before being broken down.
The truth is, there are well over 1000 different chemicals (!) in Kava, any number of which may have anti-anxiety drug effects, either in isolation or in combination with each other. Any search for the one chemical that makes Kava work may be futile.
Studies in humans with a range of anxiety levels have shown that Kava is a very effective treatment, with little demonstrated side effects (see box). Kava is effective in treating sub-clinical (mild) anxiety, clinical (severe) anxiety, anxiety associated with a disease (such as cancer), and anxiety that occurs before an event (such as before surgery).
Side effects tend to occur in less than 5% of the people who take Kava, and are considered mild or negligible (not significant). The most well-known side effect of Kava, "kava dermopathy", occurs primarily in people who take large amounts of this herb every day for long periods of time (over three months). Kava dermopathy is a rash that starts in the face and works its way down the body. This rash usually does not appear in people who take Kava as a supplement, but is common in people in the tropical areas where Kava grows and who consume a large amount of this herb every day. The rash disappears when Kava is stopped.
Safety and Dosing
Kava is generally considered safe when taken as directed. The normal dose for Kava is 50-70 milligrams of a standardized kavalactones preparation, three times a day. Kava has only been studied for short-term use (1-24 weeks). Continuous long-term use is not recommended.
Kava has the potential to interfere with other drugs and should not be used with sedative-hypnotics (sleep aids or tranquilizing medicine), anxiolytics (anti-anxiety medicine), or MAO inhibitors (a type of antidepressants). Taking Kava with alcohol is also potentially dangerous and should be avoided. You should never drive or operate heavy machinery when taking Kava.
There is always a potential for an allergic reaction to any medication. If you experience any itching, swelling, difficulty breathing, increased heart rate or any other symptom that worries you, stop using Kava immediately.
Special Note: Kava was previously thought to cause liver failure in a few cases Europe. However, additional studies of Kava-induced liver toxicity failed to show any connection between taking this herb and subsequent liver damage. It is now assumed that the Kava taken by the Europeans who experienced liver failure was somehow adulterated (changed or tampered with), but this has not been proven. Consult a health practitioner before starting any herbal therapy, especially if you have a history of previous or current liver problems.