Gotu Kola Shows Anxiety-Reducing Activity in Clinical Trial

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Reviewed: Bradwein J, Zhou Y, Koszycki D, Shlik J. A Double-Blind, Placebo-Controlled Study of the Effects of Gotu Kola (Centella asiatica) on Acoustic Startle Response in Healthy Subjects. Journal of Clinical Psychopharmacology 2000;20(6):680-4.

The herb gotu kola (Centella asiatica (L.) Urb., Apiaceae) is mainly found in the marshy areas throughout India, Malaysia, Madagascar and East Africa, in South America and in the southern U.S. Also commonly called Indian pennywort, it has been used in traditional Ayurvedic and Chinese medicine to treat depression and anxiety, among other uses. Experiments with rats have shown that gotu kola alleviates some of the symptoms of anxiety, including the acoustic startle response (ASR). This study is the first known double-blind, placebo-controlled experiment to assess the effects of gotu kola on ASR in healthy human subjects. ASR is a distinct set of physiological responses (like an eye blink) that result from an unexpected external stimulus, such as a loud noise. The response is amplified in fear and anxiety disorders and has been used to investigate these disorders in humans. Using a sensor mounted in a pair of glasses, ASR was tested by measuring eye blinks resulting from a loud noise.

Forty healthy subjects aged 18-45 years were administered a one-time dose of either 12 g gotu kola powder (Nature's Way of Canada Ltd., Newmarket, Ontario) mixed into 300 ml grape juice or a placebo of 300 ml plain grape juice (1 mg of celery salt was added to both mixtures to match color, taste, and smell). ASR, heart rate, blood pressure, and mood data were recorded at baseline, and at 30, 60, 90, and 120 minutes after ingestion. The startle response was statistically significantly lower 30 and 60 minutes after ingestion of gotu kola compared to placebo, with an effect size of 0.48 and 0.77 respectively, indicating some anti-anxiety activity. There was no difference between placebo and gotu kola treatment for later times or at baseline. Also, there was no difference for heart rate or blood pressure, and no difference in mood response except for self-rated energy level. The authors note, however, that anxious, fearful and nervous mood ratings were low in the subjects at baseline. All treatments were well tolerated with no adverse events.

Although used for thousands of years for its cognitive effects, the mechanism of action of gotu kola is unknown. Active ingredients include asiatic acid, madecassic acid, and asiaticoside, which may interact with cholecystokinin receptors or GABA (gamma-aminobutyric acid) receptors (known to be involved in the pathophysiology of anxiety). The next level of investigation would be clinical trials to assess long-term use of gotu kola.

PHOTO (COLOR): Gotu kola Centella asiatica.

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By Risa N. Schulman, Ph.D.

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