Kava and CBD: two plants, two different mechanisms

2022-11-09 · 6 min read

By the kava.fyi editorial team · Last updated: 9 November 2022

Kava and CBD often get lumped together under the label "natural calm," but beyond that they have little in common. They come from plants in different families, contain entirely different active compounds, act on the nervous system in different ways, and fall under separate regulations. Below we set out the facts, without settling which one is "better."

Two plants from different families

Kava is a drink made from the underground parts of the kava plant (Piper methysticum), a perennial shrub in the pepper family (Piperaceae). The plant is dioecious, but its flowers are sterile: it produces no viable seed and propagates only from stem cuttings. At harvest it is typically 2 to 2.5 m tall. The drink is prepared from the roots, rhizome and lower stem sections, while the above-ground parts are traditionally discarded.

CBD, or cannabidiol, comes from hemp (Cannabis sativa L.), an annual herbaceous plant in the hemp family (Cannabaceae). Hemp is also dioecious, but unlike kava it propagates from seed. Cannabinoids form mainly in the glandular hairs of the female flower clusters, which is why the flower tops, not the root, are the raw material used for extraction.

Active compounds: kavalactones and cannabinoids

Kava's effects are down to kavalactones. The six main ones are kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin and desmethoxyyangonin; according to a review in Nutrients, they make up around 96 per cent of the lipid extract. Total kavalactone content ranges from 3 to 20 per cent of dry weight, depending on the cultivar, growing conditions and plant part. The proportions of individual kavalactones vary between cultivars, a pattern described as chemotype; you can find an overview of cultivars in the cultivar atlas.

More than a hundred cannabinoids have been described in hemp, most of them present only in trace amounts. The two most important are THC (tetrahydrocannabinol), the main psychoactive component, and CBD. Cannabidiol does not produce the intoxication typical of THC. Under both EU and Polish law, it is THC content, not CBD, that determines whether a plant counts as "industrial hemp."

How they act on the nervous system

Kava: direct potentiation of GABA-A

A 2016 study by Chua and co-authors showed that kavain, the best-studied kavalactone, positively modulates GABA-A receptors across every subunit configuration tested, and the effect does not disappear when flumazenil is administered. This means kavain does not act through the classic benzodiazepine binding site, even though it potentiates the inhibitory GABA signal. We cover this mechanism in more detail in the article kava and GABA. It is worth remembering that kava is a psychoactive substance: the species name methysticum itself means "intoxicating."

CBD: many targets, weak affinity for cannabinoid receptors

The popular explanation that CBD "regulates the endocannabinoid system" is a simplification. A review by Pertwee in the British Journal of Pharmacology reports that cannabidiol has surprisingly low affinity for CB1 and CB2 receptors (Ki values in the micromolar range), while at low concentrations it behaves as an antagonist of agonists at those receptors. Ibeas Bih and co-authors counted more than 65 distinct molecular targets for CBD described in the literature, but judged only a small subset credible: the 5-HT1A serotonin receptor, the TRPV1 channel, the GPR55 receptor, PPARγ, and the adenosine system. The authors state outright that CBD's effects in neurological disorders probably do not stem from modulation of the endocannabinoid system.

Setting these two mechanisms side by side shows the main difference: kavalactones have a well-documented, direct target (GABA-A), while CBD acts diffusely, across many targets of varying strength.

Legal status in the European Union

For CBD, two documents matter most. A ruling of the Court of Justice of the EU of 19 November 2020, in Case C-663/18, held that CBD extracted from the whole hemp plant is not a narcotic drug within the meaning of the 1961 Single Convention, since current scientific knowledge finds no psychotropic effect. The Court also ruled that a member state cannot ban the sale of CBD lawfully produced in another EU state unless it can show that doing so is necessary to protect public health.

The second document concerns food. The European Commission treats CBD as a novel food requiring authorisation before it can be placed on the market. In June 2022, EFSA reported that it had received 19 applications but had put its evaluations on hold because of gaps in the data on CBD's effects on the liver, the gastrointestinal tract, the hormonal and nervous systems and mental wellbeing, as well as because of reproductive effects observed in animals. EFSA stressed at the same time that it had not found CBD as a food to be unsafe.

Legal status in Poland

Hemp and CBD. An amendment to the Act on Counteracting Drug Addiction of 24 March 2022 (Journal of Laws 2022, item 763), in force since 7 May 2022, defines industrial hemp as Cannabis sativa L. plants in which the combined delta-9-THC and THCA content in the flowering or fruiting tops does not exceed 0.3 per cent of dry weight.
Kava. Under an Act of 20 March 2009 amending the Act on Counteracting Drug Addiction, kava was placed on the list of group I-N narcotic drugs, making it illegal to possess live plants, dried root, seeds or extracts. In December 2016, an advisory team at the Chief Sanitary Inspectorate recommended removing the species from the list. A regulation of the Minister of Health of 17 August 2018 (Journal of Laws 2018, item 1591), in force since 21 August 2018, no longer lists Piper methysticum on any schedule.

Its removal from the schedule concerns narcotics law specifically. Classifying products as food is a separate area of regulation, so before buying or selling it is worth checking the current position of the relevant authorities.

Safety: where the open questions lie

Both substances have open research questions. For kava, the debate centres mainly on the liver and on raw-material quality (noble cultivars, underground parts only); see more in the article kava and the liver. For CBD, it is precisely the lack of data on effects on the liver and the hormonal and nervous systems that stalled EFSA's evaluation. Neither product is a medicine, and neither replaces a doctor's advice, especially alongside other medicines.

Summary of the differences

Plant: a perennial, sterile shrub in the pepper family (kava) versus an annual herbaceous plant in the hemp family (CBD).
Raw material: root and rhizome (kava) versus female flower clusters (CBD).
Active compounds: six main kavalactones versus cannabidiol, one of more than a hundred cannabinoids.
Mechanism: positive modulation of GABA-A versus multiple targets with weak to moderate affinity.
Law in the EU: CBD is not a narcotic drug according to the CJEU, but is a novel food requiring authorisation; kava has not appeared on Poland's list of narcotic drugs since 2018.