For thousands of years, the Khoikhoi and San people of South Africa harvested this herb for its effects on the mind and body. It’s a powerful antidepressant with few side effects, and you can grow it in your living room. Read on to find out more about kanna.
What is Sceletium Tortuosum (Kanna)?
Sceletium tortuosum is a South African succulent plant. Local people traditionally ferment the plant into its medicinal form—called kanna, channa, or kougoed—and chew it to relieve hunger, thirst, and pain. Centuries-old reports of its use describe hunters and farmers washing their aching legs with kanna. Kanna is also a psychoactive herb: it is used to reduce anxiety and stress, but it is neither hallucinogenic nor addictive.
Modern scientific research suggests that kanna may, in fact, be a very useful herb. Its active compounds may help with anxiety and depression, improve mood, and kill pain.
- Fights anxiety and depression
- Promotes feelings of calm and focus
- May relieve pain
- Suppresses hunger
- Long history of traditional use
- Extremely safe at all tested doses
- No apparent risk of addiction
- Can be grown as a houseplant
- Very limited modern research pool
- Will not work for everyone
- May cause nausea in first-time users
- Potentially dangerous drug interactions
Kanna’s most important chemical compounds are alkaloids: mesembrine, mesembrenone, mesembrenol, mesembranol, epimesembranol, and tortuosamine. Of these, mesembrine and mesembrenone are thought to be the most active.
Health Benefits of Kanna
1) Fights Depression and Anxiety
Kanna’s mechanism of action is very similar to many prescription antidepressant and anti-anxiety medications. Like Prozac, Zoloft, Cymbalta, and many others, kanna increases the amount of serotonin available in the brain [R].
Mesembrine and complete Sceletium tortuosum extract may be effective natural antidepressants. In clinical studies, people who took Sceletium tortuosum (as Zembrin, the most common commercially available extract) reported improved sleep and reduced stress. In rats, a purified extract of Sceletium tortuosum was about half as effective as imipramine, a tricyclic antidepressant drug [R, R].
A few psychiatric doctors in South Africa prescribe kanna to patients with depression, mild depression (dysthymia), and anxiety. These reported case studies have been successful; in some cases, patients have responded better to kanna than to conventional antidepressants like citalopram [R, R].
Note, however, that these case studies are limited and possibly biased: the doctor reporting them has a long history of studying traditional African medicine, but he is also credited as the Medical and Scientific Director of the company that sells Zembrin. He may have a financial incentive to promote the supplement [R, R].
In a cell study, a Sceletium tortuosum extract rich in mesembrine decreased the stress hormone cortisol. Researchers suggested that the extract may be useful in people with high stress and high blood pressure; these results have yet to be verified in animal or human studies.
Inflammation and Depression
Depression and inflammation are closely linked, and some cases of depression may be caused by high levels of inflammatory molecules called cytokines. In one study, cells exposed to Sceletium tortuosum extract increased expression of IL-10, a unique cytokine that lowers inflammation and reduces the expression of other inflammation-promoting cytokines.
In this way, the kanna protected immune cells and reduced the inflammatory response, which may partially explain its antidepressant properties. However, this effect has yet to be observed in animal or human studies.
2) May Improve Cognition
In psychology, “executive function” describes a person’s ability (or lack thereof) to plan, solve problems, and complete tasks. Mental illness and psychiatric disorders often damage a person’s executive function: depression, anxiety, autism, and even obesity all reduce our ability to get things done.
Early clinical studies suggest that kanna may improve executive function and cognitive flexibility. In one study, people enjoyed significant increases in these two areas after supplementing with 25 mg/day of kanna for 9 weeks. Unfortunately, this study only recruited 35 healthy adults between the ages of 45 and 65; larger studies with more varied people will demonstrate whether this benefit is significant [R].
Alzheimer’s disease is marked by a significant decrease in cognition; researchers have identified phosphodiesterase 4, or PDE4, as a possible target for new Alzheimer’s medication. Because of its ability to block PDE4, kanna may alleviate early symptoms of Alzheimer’s. There have not yet been any clinical trials to determine whether this hypothesis plays out in reality [R, R].
3) Kills Pain
According to traditional medicine and animal studies, kanna is an effective natural painkiller. In a rat study, mesembrine from kanna was slightly less effective than the strong opioid morphine. Traditional practitioners would rub kanna on the aching legs of hunters and farmers, and pregnant women would chew it to soothe their aches and pains. They would even give drops of kanna to crying babies to help them sleep [R, R].
High doses of kanna activate opioid receptors in the brain, so this evidence of painkilling properties is not surprising. We naturally produce opioids–endorphins and enkephalins–to soothe feelings of pain and boost sensations of reward and pleasure. Other compounds that bind to opioid receptors include morphine and oxycodone; unlike these prescription painkillers, kanna does not appear to be addictive.
4) Decreases Hunger
Kanna’s active compounds bind to the receptor for cholecystokinin-1. This receptor, when activated, reduces the sensation of hunger; kanna may, therefore, help stop people from overeating. Historical records support this potential effect: two sources from the early 1900s report that kanna decreases appetite and hunger. However, no modern studies have investigated this claim [R, R, R].
Kanna: A Herb with a Unique Mechanism of Action
Serotonin Reuptake Inhibition
Serotonin is a neurotransmitter with a wide array of important functions in your brain and in the rest of your body. It regulates mood, sleep, food intake, and a variety of behaviors.
Low serotonin levels or activity in certain parts of the brain can worsen mood and may lead to depression. On the other hand, activating specific serotonin receptors can trigger a psychedelic state with powerful feelings of mysticism and importance [R, R, R].
Mesembrine from kanna is a serotonin reuptake inhibitor: it prevents serotonin from being absorbed and hidden away in the neurons. This allows serotonin to stay active for longer and have a stronger effect on your brain. In this way, it reduces hunger and increases positive emotions. This may also explain the mind-expanding effects of kanna some users report, although these have not been scientifically confirmed [R].
Vesicular monoamine transporter 2, or VMAT2, is a protein that transports neurotransmitters out of the cell, where they can have their effects. In the brain, VMAT2 transports—and thereby activates—molecules like dopamine, serotonin, and GABA [R].
One study suggests that mesembrine increases the activity of VMAT2. If true, then kanna may increase available serotonin in two ways: by increasing the amount of serotonin released by each cell and by decreasing the amount reabsorbed [R].
VMAT2 releases a variety of different neurotransmitters in different parts of the brain; kanna’s effects on these other molecules has not been studied.
In addition to increasing serotonin, mesembrenone also boosts energy use in the body by blocking an enzyme called phosphodiesterase 4, or PDE4 [R].
PDE4 breaks down a messenger molecule called cyclic adenosine monophosphate, or cAMP. cAMP is crucial for energy balance–it is among the key metabolic controllers in cells. cAMP increases fat-burning and acts on glucagon, adrenaline, and immune cells. It also activates a pathway that forms long-lasting memories.
When mesembrenone blocks PDE4, it makes more cAMP available for longer in the blood and increases cAMP’s effects.
In rats, active compounds of Sceletium tortuosum extract also activate the receptors for GABA, opioids, cholecystokinin, prostaglandins, and melatonin.
GABA calms brain activity and can decrease anxiety; natural opioids kill pain and create a sense of wellbeing; cholecystokinin reduces hunger and prevents inflammation in the gut, and melatonin improves sleep quality. Prostaglandins are complex molecules, but the receptor Sceletium activates (EP4) may support gut health and prevent whole-body inflammation [R, R, R, R, R, R, R].
High doses of either Sceletium or mesembrine were used to trigger such wide-spread activation in rats. These effects have not been observed in human trials.
Kanna is considered very safe. No side effects are expected up to a dose of 6 mg per kg of body weight per day, or 420 mg in an average adult human; however, some people may experience nausea until their body gets used to the herb. According to traditional practitioners, this should only take one or two doses.
There have been no toxicology studies on the safety of giving kanna to children. However, traditional practitioners give small amounts of kanna to infants to help them sleep. We recommend talking to your doctor before giving any bioactive supplements to children [R, R].
Likewise, pregnant women traditionally chewed kanna to relieve nausea and indigestion. According to tradition, this practice does not cause abortion or congenital defects. However, as with children, the safety profile of kanna in pregnant or breastfeeding mothers has not been studied. We recommend caution.
According to both traditional knowledge and rat studies, kanna is unlikely to be addictive. Rats do not actively seek out the herb like they would seek out an addictive drug; in multiple anecdotal reports, people have suddenly stopped taking kanna with no adverse effects or withdrawal symptoms.
Kanna and Pets
One Japanese research group studied kanna’s safety for cats and dogs and found no toxic effects at a dose of 10 mg per kg of body weight per day in dogs and 100 mg/kg/day in cats [R].
10 mg/kg is equivalent to 227 mg for a 50 pound dog; 100 mg/kg is equivalent to 454 mg for a 10 pound cat. No studies have found any benefit to giving kanna to dogs or cats, so we don’t recommend giving it to them on purpose; however, if your companion accidentally ate some, he or she is probably fine. Watch for signs of poisoning like vomiting, diarrhea, and lack of energy; contact your vet if you’re concerned.
Drug Interactions – Antidepressants
Too much serotonin in the nervous system can cause a condition called serotonin syndrome. In minor cases, people experience symptoms like tremor, twitching, anxiety, insomnia, and increased heart rate. If serotonin levels get high enough, this syndrome can cause seizures, delirium, and extremely high body temperature. In extreme cases, a person suffering from serotonin syndrome can fall into a coma. The symptoms of this condition vary from person to person, and they range from mild to life-threatening.
Many antidepressants work primarily by increasing the amount of available serotonin in the brain. Similarly, kanna increases available serotonin; it may be dangerous in people who are already taking antidepressant medication.
Monoamine oxidase inhibitors (MAOIs), selective serotonin reuptake inhibitors (SSRIs), and serotonin and norepinephrine reuptake inhibitors (SNRIs) should not be combined with kanna.
This class of drugs includes:
This class of drugs includes [R]:
This class of drugs includes:
If you are taking any medication for depression or anxiety, talk to your doctor before using kanna.
Very few drugs and substances have specifically been tested for interactions with kanna. Some anecdotal evidence suggests that it may enhance the effects of alcohol and cannabis [R].
Kanna is a serotonin reuptake inhibitor, like the SSRIs listed above. Such medications interact dangerously with many other substances, such as [R]:
- St. John’s Wort
We recommend caution when combining bioactive supplements with medication.
Genetics of Response
Genes Affecting Serotonin
Many researchers have investigated the interaction of SSRIs with genetics. Because kanna shares a mechanism with this class of drugs, the genes that affect SSRIs are likely to affect kanna in a similar way. Note, however, that these genes have not been connected specifically to kanna; more research is required to confirm any direct interactions.