June/July 2020 Issue

Ask the Expert: Kava
By Toby Amidor, MS, RD, CDN, FAND
Today’s Dietitian
Vol. 22, No. 6, P. 8

Q: My clients have been asking about the use of kava for conditions such as anxiety and insomnia. Is there any scientific evidence to support these claims?

A: Kava supplements may have a small antianxiety effect, but they also have been linked to a risk of severe liver damage. Research into kava’s effects on other conditions has shown little or no benefit. Here’s an overview of the research on kava and why there have been mixed conclusions about its use for anxiety and other conditions.

Kava (Piper methysticum) is a member of the pepper family native to the islands of the South Pacific. Historically, Pacific Islanders have used kava in ceremonies to bring on a state of relaxation; today, kava is a popular antianxiety supplement in the United States. The active constituents in kava, kavalactones, are thought to produce skeletal muscle relaxation, nonnarcotic anesthesia, and local anesthetic effects. The root and underground stem (fresh or dried) are used in beverages and made into extract, capsules, and tablets. Numerous supplement companies produce kava root supplements, including Oregon’s Wild Harvest Kava Root Capsules, Gaia Herbs Kava Root Vegan Liquid Capsules, and NOW Supplements Kava Kava Extract Capsules.

The Research
A 2013 study enrolled 75 participants in a six-week double-blinded, randomized, placebo-controlled study of aqueous extract of kava on generalized anxiety disorder (GAD). There was a significant reduction in anxiety in the kava group compared with placebo in those with moderate GAD, and the supplement had an even greater effect in those with moderate to severe GAD. Researchers concluded that kava may be a moderately effective short-term option for treatment of GAD.1

Another 2013 study examined kava supplementation for withdrawal or addictive effects in a six-week, double-blinded, randomized controlled trial, also with 75 participants given kava or placebo. No differences in symptoms of withdrawal or addiction were found between groups.2

Other research suggests kava doesn’t reduce anxiety more than placebo. A 2005 randomized, double-blinded, placebo-controlled trial conducted remotely looked at the effects of kava for anxiety and improving sleep quality over four weeks. E-mail recruitment letters and banner advertisements on websites were used to recruit 1,551 participants from 45 states, and supplements and placebos were mailed to participants. Researchers found that kava didn’t relieve anxiety or insomnia more than placebo.3 A 2012 study showed similar results, with no effect on anxiety.4

There have been concerns of severe liver toxicity connected to taking kava supplements. In March 2002, the FDA issued an advisory to consumers about the potential risk of severe liver injury from the use of dietary supplements containing kava.5 Furthermore, in January 2003, kava extract was banned in the entire European Union and Canada, with officials citing at least 25 cases of liver toxicity, including hepatitis, cirrhosis, and liver failure.5,6

Other safety concerns exist as well; for example, combining kava with alcohol may increase the risk of liver damage, and long-term use of high doses of kava has been associated with dry, scaly skin or yellowing of the skin and can cause low blood platelets and white blood cells. In addition, heavy consumption of kava has been linked with heart problems and eye irritation.5 Kava also may interact with benzodiazepines, barbiturates, sedatives, and acetaminophen.

Recommendations for Clients
As previously stated, there’s mixed evidence on kava’s antianxiety properties and little or no evidence for other health claims. Dietetics professionals should question clients to determine why they’re taking kava and perhaps find an alternative resource (eg, referral to a psychiatrist, psychologist, or other health professional) to help treat anxiety, sleep issues, and addiction/withdrawal. RDs also should discourage long-term use, especially at high doses, and the concurrent use of kava and alcohol.

— Toby Amidor, MS, RD, CDN, FAND, is the founder of Toby Amidor Nutrition (http://tobyamidornutrition.com) and a Wall Street Journal best-selling author. Her cookbooks include The Best Rotisserie Chicken Cookbook, The Create-Your-Plate Diabetes Cookbook, Smart Meal Prep for Beginners, The Easy 5-Ingredient Healthy Cookbook, The Healthy Meal Prep Cookbook, and The Greek Yogurt Kitchen. She’s a nutrition expert for FoodNetwork.com and a contributor to U.S. News Eat + Run and other national outlets.


1. Sarris J, Stough C, Bousman CA, et al. Kava in the treatment of generalized anxiety disorder: a double-blind, randomized, placebo-controlled study. J Clin Psychopharmacol. 2013;33(5):643-648.

2. Sarris J, Stough C, Teschke R, et al. Kava for the treatment of generalized anxiety disorder RCT: analysis of adverse reactions, liver function, addiction, and sexual effects. Phyother Res. 2013;27(11):1723-1728.

3. Jacobs BP, Bent S, Tice JA, Blackwell T, Cummings SR. An internet-based randomized, placebo-controlled trial of kava and valerian for anxiety and insomnia. Medicine (Baltimore). 2005;84(4):197-207.

4. Sarris J, Scholey A, Schweitzer I, et al. The acute effects of kava and oxazepam on anxiety, mood, neurocognition; and genetic correlates: a randomized, placebo-controlled, double-blind study. Hum Psychopharmacol. 2012;27(3):262-269.

5. Kava linked to liver damage. National Center for Complementary and Integrative Health website. https://nccih.nih.gov/news/alerts/kava. Updated March 26, 2018.

6. Clouatre DL. Kava kava: examining new reports of toxicity. Toxicol Lett. 2004;150(1):85-96.