The short version
- A 2017 systematic review and meta-analysis of 11 randomised trials found no significant difference between Centella asiatica and placebo in any cognitive function domain.
- The same meta-analysis did find acute mood effects one hour after a dose: alert scores rose (SMD 0.71, 95% CI 0.01 to 1.41) and anger scores fell (SMD -0.81, 95% CI -1.51 to -0.09).
- The trial most often cited for gotu kola and memory enrolled 28 healthy elderly volunteers across three dose arms, and only the 750mg dose enhanced working memory.
- A systematic review of eight randomised trials found Centella asiatica significantly improved microcirculatory measures in chronic venous insufficiency, including transcutaneous gas pressures and the rate of ankle swelling.
- None of the cognitive trials included in the 2017 meta-analysis reported adverse effects of Centella asiatica.
gotu kola is sold in the West as a brain tonic, which is a fair translation of how it has been used in Ayurveda for a very long time. It turns up in most nootropic blends, and we put it in a capsule ourselves. So it is worth being direct about what happened when somebody finally pooled the trials.
The meta-analysis, and the sentence that matters
In 2017 a Thai and Malaysian research group published the first systematic review of centella asiatica and cognition in Scientific Reports. They found five randomised controlled trials of the herb alone and six more of products containing it.
Their finding: no significant differences in any cognitive function domain compared with placebo. Not memory, not attention, not executive function. The traditional reputation did not survive the pooling.
What did survive was smaller and more specific. One hour after a dose, alert scores rose (SMD 0.71, 95% CI 0.01 to 1.41) and anger scores fell (SMD -0.81, 95% CI -1.51 to -0.09). Both confidence intervals scrape zero, which is honest to say. None of the included studies reported adverse effects.
So the pooled human evidence describes an acute mood effect measurable within an hour, and no cognitive effect at all. If you are buying this to remember more, the meta-analysis is not on your side.
The trial the marketing is built on
The positive study people cite is from Khon Kaen University in 2008: 28 healthy elderly volunteers given 250, 500 or 750mg of extract daily for two months, tested on a computerised battery with event-related potentials, plus mood scales.
The high dose — and only the high dose — enhanced working memory and increased the N100 amplitude of the event-related potential. Self-rated mood improved across the treatment.
Twenty-eight people split across three dose arms is roughly nine per group. A dose-response pattern in a study that size is suggestive and it is not a foundation. It is also, notably, the paper that gives this ingredient its cognitive reputation, and the later pooling of the whole literature did not reproduce it.
Where the evidence is actually better
Here is the part almost nobody selling gotu kola for focus mentions. Its strongest clinical file is vascular.
A systematic review of centella asiatica in chronic venous insufficiency — heavy, aching, swelling legs — found eight randomised trials. Pooling the comparable ones showed significant improvement in microcirculatory measures: transcutaneous partial pressure of carbon dioxide and oxygen, the rate of ankle swelling, and the venoarteriolar response. Three of the eight studies gave no usable quantitative data, and the reviewers flag inadequate reporting and unclear risk of bias throughout, so this is a promising file rather than a settled one.
Still: measurable changes in microcirculation, in eight trials, versus nothing in any cognitive domain across eleven. That is a real asymmetry, and the ingredient is marketed almost entirely on the weaker half of it.
Why it is still in our capsule
Two honest reasons. It has a long traditional pairing with bacopa monnieri, and there is a real if modest acute mood signal — more alert, less irritable, within the hour — which several customers report and which the meta-analysis does support.
What we are not going to do is imply that the cognitive work is carried by this ingredient. In our formula, bacopa is the one with the memory evidence, on a twelve-week clock, with millisecond-scale effects on speed tests and a genuine null trial in its file. gotu kola is there for the calm-alert side, and that is the size of the claim.
If a brand tells you gotu kola sharpens memory, ask them which trial. The pooled answer across eleven randomised studies is that it does not.
What we'd actually tell you
Judge this ingredient on the hour, not the month. The measured effect is an acute one — alertness up, anger down, roughly sixty minutes after a dose — so if you are going to test it, test it on a specific afternoon rather than over a season, and notice mood and irritability rather than recall.
If your reason for buying it is memory, spend the money on something with a memory file. If your reason is heavy, aching legs at the end of a standing shift, the vascular literature is more interesting than the cognitive one, and that is a conversation to have with a pharmacist rather than a supplement brand.
And as always: if your thinking has genuinely changed, that is a rule-out job before it is a shopping job. Iron, thyroid, mood, medication — and sleep debt ahead of all of them, since two weeks of six-hour nights outweighs anything a botanical has been shown to do. Every one of those beats a plant extract for both odds and cost.
Good questions
Does gotu kola improve memory?
The pooled evidence says no. A 2017 meta-analysis of 11 randomised trials found no significant difference from placebo in any cognitive domain, including memory. A single 28-person trial found working memory improved at the highest of three doses, and that result has not been reproduced when the whole literature was combined.
What does gotu kola actually do?
Two things have measurable support. In cognitive trials, an acute mood effect about an hour after a dose: more alert, less angry. Separately, in eight trials in people with chronic venous insufficiency, it improved microcirculatory measures such as the rate of ankle swelling. The vascular file is the stronger of the two.
How long does gotu kola take to work?
About an hour, for the only effect the meta-analysis found. That is a genuinely different pattern from bacopa, which needs roughly twelve weeks before anything is measurable. If you are testing gotu kola, test it on a specific afternoon and watch mood and irritability rather than waiting a season for recall to change.
Is gotu kola safe?
None of the cognitive trials in the 2017 meta-analysis reported adverse effects, which is reassuring as far as it goes. The dataset is small and the reviewers noted wide variation in dose, preparation and standardisation between products. As with any botanical, check with a pharmacist if you take prescribed medicines.
Why do you sell gotu kola if the cognitive evidence is negative?
Because the acute mood signal is real and the ingredient is well tolerated, and because it pairs traditionally with bacopa, which is the one carrying the memory evidence in our formula. We are not going to claim gotu kola sharpens recall. If memory is your goal, that expectation should sit on the bacopa.
Is gotu kola the same as kola nut?
No, and the names cause real confusion. Gotu kola is Centella asiatica, a low-growing herb with no caffeine in it at all. Kola nut is a caffeine-containing seed from a completely unrelated tree. If you are avoiding stimulants, gotu kola is not one, and nothing in this article is about kola nut.
Sources
- Puttarak P, Dilokthornsakul P, Saokaew S, et al. Effects of Centella asiatica (L.) Urb. on cognitive function and mood related outcomes: A Systematic Review and Meta-analysis. Sci Rep, 2017. View study
- Wattanathorn J, Mator L, Muchimapura S, et al. Positive modulation of cognition and mood in the healthy elderly volunteer following the administration of Centella asiatica. J Ethnopharmacol, 2008. View study
- Chong NJ, Aziz Z. A Systematic Review of the Efficacy of Centella asiatica for Improvement of the Signs and Symptoms of Chronic Venous Insufficiency. Evid Based Complement Alternat Med, 2013. View study
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
