For horses · Jun 13, 2016
Gotu kola boosts brain GABA, and it actually gets in there to do it
Gotu Kola (Centella asiatica) nudges your brain to make more of its own GABA, which is a very different thing from swallowing a GABA supplement that can’t cross the blood-brain barrier.
Gotu kola (*Centella asiatica*) is one of my favourite natural calming herbs, and the science genuinely backs it up. Its triterpenoids boost the activity of glutamate decarboxylase (GAD) by over 40%, which means the brain is actually making more GABA. On top of that, asiatic acid sits at the benzodiazepine site on GABA-A receptors, so it’s working two angles at once, without the sedation. A double-blind, placebo-controlled human trial showed a single oral dose significantly reduced acoustic startle response. Generally well tolerated, though rare cases of mild liver upset have been reported, worth knowing.
Common misconception: Taking GABA as a supplement calms the nervous system
I get why this one sticks around, the logic feels perfectly reasonable. GABA is the brain’s main calming chemical, the thing that damps down neuronal firing and stops the nervous system from spinning out. So if your horse or dog is anxious, just top up their GABA, right?
Not quite. GABA taken orally doesn’t cross the blood-brain barrier. That barrier is there specifically to protect the brain from molecules circulating in the bloodstream, and GABA, a charged amino acid, is one of the things it keeps firmly out. So anything you tip into a feed bucket labelled “GABA” never actually gets to where it would need to go. This is true for all mammals, horses included.
This is exactly why I think Gotu Kola (Centella asiatica) is so worth understanding. Rather than trying to deliver GABA from the outside, its triterpene constituents work with the brain’s own production machinery from the inside. Gotu Kola extracts have been shown to stimulate glutamate decarboxylase (GAD), the enzyme that converts glutamate into GABA, by over 40% in brain tissue assays [1]. That’s more GABA made right where it’s actually needed.
And it doesn’t stop there. Asiatic acid, one of Centella asiatica’s key triterpenes, acts at the benzodiazepine binding site on GABA-A receptors. Researchers confirmed this was genuine receptor-mediated activity by blocking the effect with flumazenil, a benzodiazepine antagonist, not a non-specific result [4]. On top of that, asiatic acid also suppresses glutamate release presynaptically by inhibiting calcium influx through N- and P/Q-type calcium channels [6], quieting neuronal excitability through a completely separate route.
The bottom line: a proprietary standardised Centella asiatica extract produced anxiolytic effects in both acutely and chronically stressed mice that were comparable to diazepam [5], and a systematic review placed it among the phytomedicines with the most consistent GABA-modulating evidence across preclinical and human clinical work [11]. Selling a product labelled “GABA” for anxiety is, at best, wishful thinking. Giving an animal the botanical tools to make and use more of its own GABA is a very different thing altogether.
How gotu kola acts on the brain’s calming chemistry
It all starts with GABA, gamma-aminobutyric acid, the brain’s main inhibitory neurotransmitter. Think of it as the nervous system’s volume-down switch. Your brain makes GABA from glutamate, and the enzyme that does that job is called glutamate decarboxylase (GAD). Here’s what’s interesting: **gotu kola (*Centella asiatica*) extracts have been shown to boost GAD activity by over 40% in brain tissue assays. That means more GABA being made right where it’s needed.
The plant’s active constituents are a trio of triterpenoids, asiaticoside, madecassoside, and asiatic acid. Asiatic acid goes straight to the GABA-A receptor and binds at the benzodiazepine site, the same site that prescription tranquillisers target. Researchers confirmed this isn’t coincidental: when they blocked that site with the antagonist flumazenil, the anxiolytic effect disappeared entirely. On top of that, asiatic acid also dials down the release of excitatory glutamate in the hippocampus by inhibiting calcium influx through N- and P/Q-type calcium channels. So you’ve got two complementary mechanisms working together, more GABA being produced, and less excitatory glutamate firing in the first place.
In rodent behavioural tests, elevated plus maze, dark-light box, open-field, standardised Centella asiatica extract matched the anxiolytic effects of diazepam, and the triterpenoids did it without causing sedation. A systematic review placed Centella asiatica among the phytomedicines with the strongest combined evidence: preclinical GABA**-modulating activity, animal model data, and human clinical trials to back it up.
How to use Gotu Kola (Centella asiatica) for calm: what the evidence actually supports
Timing and onset
The single-dose (using a large dose of 12 grams) startle study is quite telling here, a measurable calming effect showed up within 30 minutes and was still there at 60 minutes. Meanwhile, the 60-day clinical trial shows that sustained daily use (mg amounts)builds real cumulative benefit. Those two timescales aren’t contradicting each other; they’re showing you two different faces of the same mechanism.
Duration
The longest well-characterised human trial ran for 60 days. That’s the window I can speak to honestly, the pool doesn’t take us beyond that, so I won’t pretend it does.
Safety and when to exercise caution
Generally speaking, Centella asiatica has a good safety record, and pharmacological testing shows negligible interaction with CYP isoenzymes, so it plays nicely with a lot of other things. That said, I won’t gloss over the fact that rare cases of clinically apparent acute liver injury with jaundice have turned up in the human literature. The NIH LiverTox database classifies this as a probable but rare event (Likelihood Score C), and where it has occurred it’s been mild-to-moderate and self-limiting. Still, if there’s any pre-existing liver compromise, I’d want professional oversight before reaching for this herb, and it’s worth keeping an eye out for any signs of liver stress during longer-term use. There’s no animal-specific dosing or contraindication data in this research pool, so please don’t transpose human figures directly to horses or companion animals without guidance from your vet.
What we’d recommend
Helps your horse stay calmer by boosting the brain’s own natural calming chemistry.
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Frequently asked questions
How does Gotu Kola actually calm anxiety, what is the mechanism?
It works along two complementary pathways, which I think is what makes it so interesting. First, Gotu Kola extracts stimulate glutamate decarboxylase (GAD), the enzyme that converts glutamate into GABA, by over 40%, so the brain produces more of its own calming neurotransmitter. Second, its key triterpene asiatic acid acts directly on the benzodiazepine binding site of GABA-A receptors, and separately damps down excitatory glutamate release by blocking calcium influx at the presynaptic membrane. That’s three distinct actions, all pointing in the same direction.
Is there clinical evidence that Gotu Kola reduces anxiety in practice, not just in lab studies?
There is, and it’s decent evidence. A double-blind, placebo-controlled human trial showed a single oral dose significantly reduced peak acoustic startle response within 30-60 minutes. A separate 60-day study in 33 people with generalised anxiety disorder, taking Gotu Kola twice daily, found significant reductions in anxiety, stress, and associated depression on Hamilton’s Brief Psychiatric Rating Scale. Not vast trial numbers, but properly controlled.
Does Gotu Kola cause sedation the way pharmaceutical anxiolytics do?
This is one of the things I really like about it. Traditional and preclinical work consistently shows anxiolytic activity without sedative effects in rodent behavioural models. And in the human startle-response trial, there were no significant changes in self-rated mood, heart rate, or blood pressure at the active dose. Compare that to benzodiazepines, which knock anxiety down but bring sedation along for the ride. With Gotu Kola, you get the calming without the fog.
Is Gotu Kola safe for horses and other animals?
Centella asiatica has a long track record of ethnoveterinary use across Ethiopia, India, and Southeast Asia, including for neurological conditions in livestock, and human clinical trials at 250-500 mg standardised extract report good tolerability with negligible interaction potential at CYP isoenzymes. I’d call that a reassuring safety profile. That said, rare cases of mild-to-moderate acute liver injury have been documented in humans, so if your animal has any pre-existing liver compromise, I’d be cautious.
Why not just give GABA as a supplement directly instead of using Gotu Kola?
Because oral GABA doesn’t cross the blood-brain barrier in mammals, it simply can’t reach the place where it needs to work. Gotu Kola gets around this neatly by stimulating the brain’s own GABA-producing enzyme (GAD) and by modulating GABA-A receptors through its triterpene constituents. The effect is generated from inside the central nervous system, rather than trying to deliver the neurotransmitter from outside it. That distinction matters enormously.
Which active compounds in Gotu Kola are responsible for the anxiolytic effects?
The main players are three triterpenoids: asiaticoside, madecassoside, and asiatic acid. Asiatic acid is the best characterised, it acts at the benzodiazepine site on GABA-A receptors, and its anxiolytic effect is blocked by the antagonist flumazenil, which confirms it’s receptor-mediated rather than a general sedative effect. Asiaticoside and madecassoside also show meaningful anxiety-relieving activity in animal models, though without marked changes in other stress markers like serum corticosterone.
Sources
- Effects of traditionally used anxiolytic botanicals on enzymes of the gamma-aminobutyric acid (GABA) system
- A double-blind, placebo-controlled study on the effects of Gotu Kola (Centella asiatica) on acoustic startle response in healthy subjects
- A clinical study on the management of generalized anxiety disorder with Centella asiatica
- Evaluation of the anxiolytic and antidepressant effects of asiatic acid, a compound from Gotu kola or Centella asiatica, in the male Sprague Dawley rat
- Anxiolytic effects of standardized extract of Centella asiatica (ECa 233) after chronic immobilization stress in mice
- Asiatic acid, an active substance of Centella asiatica, presynaptically depresses glutamate release in the rat hippocampus
- Centella asiatica – LiverTox – NCBI Bookshelf – NIH
- Therapeutic Potential of Centella asiatica and Its Triterpenes: A Review
- Pharmacological Review on Centella asiatica: A Potential Herbal Cure-all
- Ethnoveterinary medicinal plants used by the Maale and Ari ethnic communities in southern Ethiopia
- GABA-modulating phytomedicines for anxiety: A systematic review of preclinical and clinical evidence
- Therapeutic properties and pharmacological activities of asiaticoside and madecassoside: A review