Kava for Anxiety, Depression, Cancer, Cognition

research shows that kava kava treats anxiety, depression and cancer

Piper methysticum. Photo by Malcolm Manners

Kava’s leaves are heart-shaped for a reason. Kava has a long and proven record of medicinal benefits. It’s time we set the record straight for this incredible herb.

New scientific research proves it treats anxiety, depression and stops the growth of several types of cancer. It also boosts cognition. All this with a record of safety. Let’s review the evidence.

What is Kava kava?

Kava kava (Piper methysticum) is a traditional herb with centuries of use among the islands of the Pacific. These include Fiji, Papua Guinea, Samoa, Solomon Islands and other Micronesia islands. These islanders consume Kava by simply mixing the whole powdered root with water. Often it is served in a coconut shell in a ceremonial social event.

The P. methysticum plant grows in the tropical jungle and lays down an impressive root system. This might be compared to the impressive roots of the ginger or the ginseng plants. Kava’s roots are harvested and dried. They are then pulverized into powder. This root powder is typically consumed in whole form, though supplement companies will often produce extracts.

Kava relieves anxiety

A number of human clinical studies have shown that Kava relieves anxiety. In a review of the research from the University of Melbourne, four of six human clinical studies conducted with P. methysticum for anxiety showed that:

“The current weight of evidence supports the use of kava in treatment of anxiety with a significant result…”

A more pervasive review was done by California’s Global Neuroscience Initiative Foundation. The review analyzed 24 studies of Kava and other herbal medicines for anxiety. The study found substantial evidence that Kava relieved anxiety. It also treated restlessness and insomnia. The researchers also reviewed animal studies that showed that Kava has anxiolytic effects “but not sedative or mental impairing” effects “which are typical side effects caused by benzodiazepines.”

P. methysticum extracts have also been seen to bind to GABA and dopamine receptors, as well as opiate receptors.

In one of these studies 101 adults were given either Kava or a placebo for 25 weeks. The Kava group showed significant improvement in “primary and secondary anxiety symptoms.”

Primary anxiety relates to long term stress and anxiety (since childhood) while secondary anxiety relates to clinical disorders.

Kava kava medicinal value

Kava’s extensive root system. Photo by Scot Nelson

Five other randomized controlled clinical trials and one observational study supported these results. They supported P. methysticum as a potential “monotherapy” (meaning no other medications give) or for those who were coming off of benzodiazepines.

The researchers noted that Kava’s use with St. John’s wort has not been productive.

Kava relieves depression

Other studies have shown Kava has antidepressant effects. A three-week study from The University of Queensland gave 60 adults 250 milligrams kavalactones per day or a placebo. At the end of the three weeks, the P. methysticum group had significantly lower levels of depression compared to the placebo group, using Montgomery-Asberg Depression Rating Scale scores.

The researchers concluded:

“The aqueous Kava preparation produced significant anxiolytic and antidepressant activity and raised no safety concerns at the dose and duration studied. Kava appears equally effective in cases where anxiety is accompanied by depression. This should encourage further study and consideration of globally reintroducing aqueous rootstock extracts of Kava for the management of anxiety.”

The Kava was also safe. The researchers also stated:

“The aqueous extract was found to be safe, with no serious adverse effects and no clinical hepatotoxicity [liver toxicity].”

Other studies have supported Kava’s antidepressant effects.

Kava improves anxiety and mood during menopause

Researchers from Italy’s University Degli Studi in Siena tested 40 women who were in menopause for between one and 12 years. The researchers gave the women 100 milligrams of P. methysticum with and without estrogen replacement therapy (HRT). After three and six months of treatment, the researchers tested the women for levels of moods and anxiety. The research found the P. methysticum treatment helped the menopausal women with their anxiety with and without HRT. They concluded:

“The results of this study show that the association of HRT and Kava-Kava extract may represent an excellent therapeutic tool for the treatment of women in stabilized menopause, in particular those suffering from anxiety and depression, given that Kava-Kava therapy accelerates the resolution of psychological symptoms without diminishing the therapeutic action of estrogens on organic disease, such as osteoporosis and cardiovascular disease.”

Other studies have shown similar effects. A review of research from the University of Illinois Medical School found that P. methysticum can significantly reduce mood-related anxiety during menopause.

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Kava improves cognition

Okay, so Kava relaxes the muscles and the mind. But doesn’t it affect cognition the way other antidepressants and anti-anxiety drugs do? Certainly, as some researchers have pointed out a tendency to “sway” when on Kava.

Despite this effect, there is clear evidence that P. methysticum actually has the opposite effect – it can boost cognition and attention.

After a review of 10 clinical studies of Kava, researchers from Australia’s Brain Sciences Institute at Melbourne’s University of Technology found that Kava significantly helped cognition, and did not impair cognition as some have assumed. Their report showed that some studies showed significant effects:

“One acute study found that kava significantly improved visual attention and working memory processes while another found that kava increased body sway. One chronic study found that kava significantly impaired visual attention during high-cognitive demand.”

The researchers looked into the mechanisms of Kava’s be benefits:

“Potential enhanced cognition may be attributed to the ability of kava to inhibit re-uptake of noradrenaline in the pre-frontal cortex, while increased body sway may be due to GABA pathway modulation.”

In a study from the University of Melbourne compared Kava to oxazepam. Yes, the P. methysticum helped relieve anxiety. But it was also found that P. methysticum did not have the negative side effects upon cognition the way the oxazepam did. They stated:

“Kava was found to have no negative effect on cognition, whereas a reduction in alertness occurred in the oxazepam [group].”

Kava stops the growth of cancer

A number of researchers have noted over the years that the Pacific Islanders that consume the most P. methysticum seem to have incredibly low cancer rates when compared to other populations. Could Kava be the reason? The research indicates yes.

Research has found that several P. methysticum components, such as Flavokawain B and Dihydromethysticin, reduce tumor growth and inhibit cancer.

A study from the University of California at Irvine illustrated that these P. methysticum compounds kill and inhibit prostate cancer tumors.

A study from the University of Minnesota found that methysticin from P. methysticum significantly inhibited NF-kappaB activation, therapy halting lung tumor growth. A 2016 study from the University of Minnesota found that Dihydromethysticin from Kava blocks the development of lung cancer.

Another 2016 study, this from the University of Hawaii, found that the Flavokawains A and B stimulate heat shock and antioxidant responses which kill liver cancer cells.

Another study showed Kava compounds suppressed TNF-alpha among cancer cells.

Yet another study from the University of California/Irvine showed flavokawain A inhibited the growth of bladder cancer cells. The researchers concluded:

“This selectivity of flavokawain A for inducing a G(2)-M arrest in p53-defective cells deserves further investigation as a new mechanism for the prevention and treatment of bladder cancer.”

Is Kava harmful to the liver?

Kava kava’s safety was stained a few years ago by a few case reports of liver toxicity. Let’s clear this up right away: The evidence shows quite the opposite. It shows that P. methysticum is safe when taken properly, and the risk to the liver is little, if even at all. In fact, as shown in the cancer research, Kava is helpful for liver cells.

This is evidenced by the fact that in late 2015, two German courts lifted the ban on Kava. They found no good evidence to support the supposed risks of Kava.

A 2015 study from the University of Münster that analyzed and reviewed the reports of risk of Kava concluded they were based on cases of mistaken identity and a lack of quality control on the part of those who administered them. The reality is that reports of liver issues were a few case reports, rather than any larger scale study.

Supporting this: In a large review of research from the University of Melbourne that included 24 clinical herbal studies, the researchers stated:

“Of the 435 clinical trial participants taking kava supplements in our review, some at high doses, no liver issues were reported. Therefore, the current review supports the conclusion that liver toxicity is indeed a rare side effect.”

The researchers also analyzed the “few” reports of Kava’s liver toxicity – the first of which was reported in 1998, well after many studies had been conducted – and stated:

“serious side effects may have occurred due to poor quality kava.”

Furthermore, researchers from Germany’s Goethe University of Frankfurt, the University of Melbourne and the Swinburne University of Technology in Australia have suggested that the reports of liver toxicity come not from ingesting Kava per se. Rather, they suggest that the evidence points to supplies of Kava that have become moldy.

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They point to the type of liver toxicity that has resulted in the few cases of slight liver toxicity (mostly resulting in increased liver enzymes) actually being caused by fungal contamination of the Kava rather than the Kava roots themselves.

A paper from the University of Sydney’s School of Pharmacy also revealed this possibility. While they weren’t convinced they did admit that, “background levels of aflatoxin have been detected in kava samples.”

The proposal – based on a thorough examination of the cases of Kava-liver issues as well as new research showing a lack of liver toxicity from properly prepared Kava – completely makes sense.

Why? Because for most of the history of the Kava industry, P. methysticum has been harvested and prepared by native populations among Pacific Islands where the plant is indigenous. The roots are often harvested in bulk and then stored in an exposed facility until preparation. As such, the handling and preparation of the dried Kava powder may easily become subjected to mold or any number of other contaminants as the roots are stored awaiting processing.

The Living CleanseA lack of manufacturing protocols in P. methysticum production in the past has thus been largely been left to native harvesting groups, because this was the major source of Kava. Market buyers were in no position to begin dictating protocols.

Increasingly, many Kava suppliers harvest and process using international manufacturing standards such as ISO, GMP and others. Because of the restrictions by first world countries now on the importation of raw ingredients, these protocols are now stricter. Still, it often depends upon the particular importer of the product – whether or not they inspect and demand adherence to good manufacturing practices.

Another study – which analyzed the components of P. methysticum, found there to be no compound in the Kava that should cause liver toxicity. They concluded:

“To date, there remains no indisputable reason for the increased prevalence of kava-induced hepatotoxicity in Western countries.”

Other evidence shows that in many of the reports of liver toxicity, alcohol consumption was involved and in some cases, pharmaceuticals that affect the liver were also involved. These of course include acetaminophen and many other over the counter drugs. After a review of most of the Kava liver toxicity cases (a little over 100), the researchers concluded:

“Alcohol is often co-injested in kava hepatotoxicity cases.”

In other words, there is enough evidence – the lack of toxicity among clinical studies, the potential for mold and other contamination of Kava root, and the ingestion of Kava with alcohol and/or other drugs – to make a case that the risk of liver toxicity from pure Kava when there is no alcohol or drugs consumed is minimal. And most of us know that both alcohol and many OTC drugs damage the liver. In fact, there are tens of thousands of liver toxicity cases every year in the U.S. alone.

Kava’s constituents

P. methysticum’s central anti-anxiety constituents are kavalactones. In fact, this is why most kava is now standardized to kavalactone content. Constituents mentioned above include flavokawains and methysticin. Others include kawain, yangonin, dihydrokavain, desmethoxyyangonin, and dihydromethysticin. These all have different neurological effects, including MAO-B inhibition in the case of desmethoxyyangonin. Kawain’s effects are sedative and tranquilizing, as well as anti-convulsant according to the literature.

The bottom line: P. methysticum provides one of the best proven herbal medications to treat anxiety and depression. It also aids cognition and some of its constituents may prevent and even treat different cancers.

How to take Kava

Unless you are in Fiji at a Kava ceremony, you’ll be taking Kava in supplement form or in imported root powder form. If you want to take Kava on a longer-term basis, you might consider a few simple measures:

1) Choose a reputable brand known for its focus on quality control.
2) Choose a product standardized to kavalactones.
3) Extracts are best because of their quality control. Non-alcohol liquid extracts are available.
4) Take only the amount as recommended by the manufacturer.
5) Take a day or two off for every four or five days used.
6) Do not consume alcohol or take any medications with Kava.
7) Do not consume Kava with other herbal medications.
8) Don’t drive after you take Kava.
9) If you have sensitive skin, consider staying out of the sun after consuming Kava, as it has been known to cause photosensitivity among some sensitive people – as do other herbs such as St. Johns Wort.

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Discover: Kava Kava Root Liquid Caps


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  • Case Adams, Naturopath

    California Naturopath, Ph.D. in Natural Health Sciences, Doctorate in Integrative Health Sciences, Board Certified Alternative Medicine Practitioner. Diplomas in Blood Chemistry, Clinical Nutritional Counseling, Homeopathy, Aromatherapy, Colon Hydrotherapy, certificates in Pain Management and Case Management/Contact Tracing. Has authored more than 30 books and hundreds of periodical articles on natural medicine. Recreational activities include surfing, sailing, running, biking, swimming, SUPing, hiking. Contact: case(at)caseadams(dot)com.

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