Andrew Weil on kava

2023-11-27 · 5 min read

By the kava.fyi editorial team · Last updated: 27 November 2023

Who is the doctor who recommends kava to patients

Andrew Weil is an American doctor and one of the world's most recognisable advocates of integrative medicine, an approach combining conventional treatment with methods drawn from natural and traditional medicine. In 1994 he founded the Center for Integrative Medicine at the University of Arizona, which today bears his name and trains doctors in combining both traditions. Weil is also a co-founder of the True Food Kitchen restaurant chain, built around the principles of an anti-inflammatory diet he developed together with restaurateur Sam Fox. He regularly appears in the media and on podcasts, where he has returned for years to the subject of kava as a plant whose potential he considers underrated, especially in the context of anxiety, a problem most conventional drug treatment addresses at the cost of side effects and the risk of dependence.

What Weil told Tim Ferriss about kava

In August 2022, Weil was a guest on The Tim Ferriss Show, in an episode devoted, among other things, to rehabilitating plants regarded as dangerous, kava included. He described kava as a natural sedative, probably the most important natural anti-anxiety product, and practically free of toxicity. He stated that kava does not interact with alcohol or other sedatives and can be used regularly over a long period.

Asked about kava's effect on sleep quality, he admitted that good research on the subject is lacking, but compared it favourably with sleeping pills, both over-the-counter and prescription. In his view, such drugs flatten sleep architecture and suppress REM sleep, while also readily leading to dependence, whereas nothing suggests that kava has similar side effects. This same comparison, a herbal remedy with a gentle profile against a pharmaceutical with a documented risk of dependence, comes up regularly in Weil's remarks and is one of the main reasons he recommends kava to patients dealing with situational anxiety.

What happens in the body when you drink kava

Scientists have still not settled on a single, certain mechanism of action for kava, but several leads are well documented. Kavalactones, kava's main active compounds, strengthen the action of GABA-A receptors in laboratory studies, the same system targeted by anxiolytic drugs of the benzodiazepine class. In a 1998 study, kava extract also reversibly inhibited the activity of the MAO-B enzyme in blood platelets, which could in theory partly explain its effect on mood, although this result comes from an in vitro study, not from a living human body. Current scientific reviews stress that the precise mechanism and the relative importance of these effects have not yet been clearly confirmed.

The German ban Weil refers to

When Weil talks about kava's safety, he has a specific story in mind. In 2002, the German agency BfArM withdrew kava-based medicines from the market following reports of liver damage. In 2014, the German Federal Administrative Court overturned this decision, ruling that the agency had not proven a causal link between kava and the reported liver damage, and rejected the argument that benzodiazepines were an equally safe alternative. An analysis published later in the scientific literature indicates that the problem mainly involved alcoholic extracts and preparations containing the plant's aerial parts, rather than traditional water-based root extracts, and that the quality of the raw material and the lack of clear cultivar, or chemotype, identification may have played a bigger role than kava itself. A joint expert assessment by the World Health Organization and the Food and Agriculture Organization of the United Nations, cited in the same analysis, found no reliable link between water-based kava preparations and liver damage, which indirectly supports what Weil says.

Why the quality of the root matters

In the scientific literature and among kava producers there is a distinction between noble cultivars, traditionally grown and consumed for generations, and two-day cultivars, also known as tudei, which grow faster but contain significantly more flavokavain B, a chemical compound linked in studies to toxic effects on liver cells. A literature review on the structure and toxicity of kavalactones and flavokavains indicates that it is tudei-type cultivars, not kava noble, that account for most of the adverse liver effects described in the literature. In other words, asking whether kava is safe without specifying which cultivar and which part of the plant is meant is an incomplete question, and it was precisely this lack of distinction that complicated risk assessment at the time of the German ban.

What kava's status looks like today

Since 2015, kava-based medicinal preparations have returned to the German market, but on prescription only. In Poland, kava kava appears on the list of substances banned from use in food supplements and foods, following a recommendation from the risk assessment team for new psychoactive substances at the Chief Sanitary Inspectorate. Across the whole European Union, kava root does not have the status of an approved novel food ingredient, so it formally cannot be legally sold as a food on the single market. Weil's opinion on kava's safety therefore concerns primarily the scientific data, not the current legal position, which remains restrictive in Europe.

Caution that is also worth remembering

Even the quoted remarks by Weil usually end with a caveat: do not combine kava with alcohol or antidepressants, and avoid it during pregnancy and breastfeeding. There is additional pharmacological reasoning behind this: laboratory studies show that kava extract and individual kavalactones inhibit several liver enzymes from the cytochrome P450 family, including CYP3A4, which is involved in metabolising a very large share of the medicines on the market. This means that combining kava with medications broken down in the liver, including some psychiatric and cardiac drugs, can alter their blood concentration, which is why it requires a doctor's advice, regardless of how safe the plant itself seems.

You can read more about kava's interactions with medications and its effect on the liver in kava and the liver and kava and medications. We also write about how other experts assess kava here, and describe the mechanism behind kavalactones in more detail on the kavalactones page.