The field that studies this relationship now has a formal
name: the gut-brain axis. It has its own journals, its own international
conferences, and, as of 2025, its own dedicated chapter in the WHO Global
Traditional Medicine Strategy, adopted by 194 Member States in May 2025 at the
World Health Assembly in Geneva.[1]
For those working at the intersection of Ayurvedic science and modern
pharmacology, this convergence is not a surprise. It is a long overdue
reckoning.
This newsletter covers what the gut-brain axis actually is,
how Ayurvedic herbs interact with it at the molecular level, and what the most
current research from 2024 and 2025 tells us about where this science is
heading.
What Is the Gut-Brain Axis and Why Does It Matter?
The gut contains approximately 500 million neurons, more than
the spinal cord, arranged in a complex network called the enteric nervous
system (ENS). This network communicates with the brain primarily through
the vagus nerve. About 80 to 90 percent of vagal fibres carry information from
the gut to the brain, not the other way around. The gut is, in the most
literal sense, talking to your brain far more than your brain is talking to
your gut.[2]
Sitting inside this enteric system are roughly 100 trillion
microorganisms collectively known as the gut microbiome. These
microorganisms produce neurotransmitters, including more than 90 percent of the
body's total serotonin and about 50 percent of its dopamine precursors. They
manufacture short-chain fatty acids (SCFAs) such as butyrate, propionate, and
acetate, which cross the blood-brain barrier and directly influence neuronal
function, neuroinflammation, and gene expression in the brain. They regulate the
hypothalamic-pituitary-adrenal (HPA) axis. They modulate the immune system,
which in turn modulates the brain.[3]
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# THE SCIENCE
WHAT BUTYRATE DOES TO YOUR BRAIN:
Butyrate, produced when gut bacteria
ferment dietary fibre, is a histone deacetylase (HDAC) inhibitor. It keeps
memory-related genes active in hippocampal neurons. Low butyrate, caused by
poor fibre intake, dysbiosis, or chronic stress, is associated with impaired
memory, depression, and increased neuroinflammatory markers.
Bacopa monnieri (Brahmi)
supplementation specifically increases gut bacteria that are dominant
butyrate producers, including Clostridium symbiosum and Butyrivibrio
crossotus, creating an indirect pathway from Brahmi supplementation to
improved brain function that most users of the herb have never heard of.
(Ref: Dinan et al., Biological
Psychiatry, 2013; Borre et al., Trends in Neurosciences, 2014; Cait et al.,
Microbiome, 2019)
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A disrupted microbiome, called dysbiosis, has been
linked to anxiety, depression, cognitive decline, Parkinson's disease,
Alzheimer's disease, and multiple sclerosis in peer-reviewed research over the
last decade.[4]
Interventions that restore microbial balance, whether through dietary change or
carefully selected herbal medicines, show measurable effects on brain function
and mental health markers.
Agni Was Not a Metaphor. It Was a Clinical Observation.
In Ayurvedic medicine, Agni describes the body's
digestive and transformative capacity. It governs not just how food is broken
down, but how sensory impressions are processed, how emotions are metabolised,
and how mental clarity is maintained. When Agni is weak, the result is Ama:
accumulated toxicity that sits at the root of virtually every disease in
Ayurvedic pathology.[17]
Now translate this into the language of 2025 microbiome
science. A well-functioning gut microbiome efficiently ferments dietary fibre,
produces SCFAs, maintains intestinal barrier integrity, and limits the entry of
bacterial endotoxins (lipopolysaccharides, or LPS) into the bloodstream. A
disrupted microbiome fails at each of these tasks. LPS enters circulation,
triggering systemic low-grade inflammation. Intestinal tight junction proteins
loosen. Neurotransmitter precursor availability drops. Cortisol spikes.
Cognitive function deteriorates.
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* PERSPECTIVE
"A disrupted gut microbiome has
been associated with depression and anxiety. Modern research validates what
Ayurveda has practiced for millennia: disturbances in mental state can be
traced to problems in the gut."
Perlmutter et al., The Microbiome in
Health and Disease from the Perspective of Modern Medicine and Ayurveda,
Medicina (MDPI), 2020 [13]
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The Ayurvedic concept of Ama is, in microbiological terms,
exactly this: accumulated metabolic endotoxins from a dysbiotic gut generating
systemic inflammatory load that reaches the brain. The 3,000-year-old clinical
description and the 21st-century molecular mechanism are describing the same
phenomenon from different ends of the same telescope.
Three Herbs, Three Pathways into the Gut-Brain Axis
The herbs discussed here are chosen because they are the three
Ayurvedic medicines for which the gut-brain axis mechanism has the most
specific, peer-reviewed evidence as of 2025. Each enters the axis at a
different point and produces a different pattern of microbiome and neurological
effects.
Triphala:
The Microbiome's Oldest Friend
Triphala is a three-fruit combination: Amalaki (Emblica
officinalis), Bibhitaki (Terminalia bellerica), and Haritaki
(Terminalia chebula). It has been prescribed as the foundational
gastrointestinal tonic in Ayurveda for over two millennia. Its modern
pharmacological identity is that of a prebiotic polyphenol complex, and
it is one of the most pharmacologically sophisticated gut-health interventions
in any traditional medicine system in the world.
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* KEY FINDING
Triphala polyphenols selectively
increase Bifidobacteria and Lactobacillus populations while simultaneously
inhibiting pathogenic gut organisms. This is prebiotic activity by
definition: feeding beneficial bacteria rather than introducing them.
Triphala lowers the Firmicutes-to-Bacteroidetes ratio, a microbiome shift
consistently associated with reduced metabolic disease risk and improved
brain health markers.
A 2024 study from the National
Institute of Immunology, New Delhi (published in Molecular Nutrition and Food
Research) demonstrated that Triphala modulates the gut-brain axis
bidirectionally in an Alzheimer's disease mouse model, reducing amyloid
burden and improving spatial memory by restoring microbial populations that
produce neuroprotective SCFAs.
(Ref: Upadhyay et al., Mol Nutr Food
Res, 2024 [11]; Peterson et al., J Altern Complement Med, 2020 [14])
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What Triphala does not do is act as a direct nootropic. Its
cognitive benefits are indirect and slower in onset than those of Brahmi or
Ashwagandha. The mechanism is upstream: by restoring Agni, it removes the
systemic inflammatory burden that was degrading brain function in the first
place. Modern pharmacology would call this reducing neuroinflammatory
background noise. Ayurveda would call it correcting Agni before treating the
mind.
Ashwagandha:
When the HPA Axis and the Microbiome Talk to Each Other
Withania somnifera, known as Ashwagandha, is Ayurveda's
best-known adaptogen. Its mechanisms on the HPA axis are well-documented:
withanolides reduce corticotropin-releasing hormone (CRH) at the hypothalamic
level, normalise cortisol, and protect hippocampal neurons from stress-induced
damage.[5] What
is far less discussed is the bidirectional relationship between this
cortisol-modulating activity and the gut microbiome.
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# THE SCIENCE
THE CORTISOL-DYSBIOSIS LOOP: HOW STRESS
DESTROYS YOUR MICROBIOME AND YOUR MIND TOGETHER
Chronic stress elevates cortisol.
Elevated cortisol increases intestinal permeability, allowing bacterial
endotoxins (LPS) to enter the bloodstream and trigger systemic inflammation.
This inflammation disrupts the gut microbiome, reducing SCFA-producing bacteria
and increasing pathogenic species. The disrupted microbiome then sends
inflammatory signals via the vagus nerve back to the brain, further
dysregulating the HPA axis and increasing cortisol output. This is a
self-amplifying, self-sustaining cycle.
Ashwagandha interrupts this loop at two
points simultaneously. First, by normalising cortisol, it reduces the
cortisol-driven intestinal permeability that initiates the cycle. Second, in
fecal co-culture studies, Ashwagandha supplementation specifically increased
Faecalibacterium prausnitzii and Eubacterium rectale, the primary
butyrate-producing bacteria depleted by chronic stress.
Ashwagandha and Kapikacchu together
strongly selected for Bacteroides thetaiotaomicron, which produces
polysaccharide A, a compound that stimulates regulatory T cell expansion in
the gut and directly suppresses gut-associated neuroinflammation.
(Ref: Cait et al., Microbiome, 2019
[9]; Chandrasekhar et al., Indian J Psychol Med, 2012 [5]; Borre et al.,
Trends in Neurosciences, 2014 [4])
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A 2025 review in International Journal of Peer Research in
Multidisciplinary Studies confirmed this multi-target action, noting that
Ashwagandha functions simultaneously as a prebiotic, an anti-inflammatory, and
an HPA axis modulator. The authors concluded that the very complexity of
Rasayana herbs like Ashwagandha is what makes them suited to treating the
inherently complex, interconnected system of the gut-brain axis.[6] It is not a design flaw
that these herbs work through multiple mechanisms. It is the point.
Brahmi:
The Gut-Brain Pathway Nobody Talks About
Bacopa monnieri's direct brain mechanisms are
increasingly known in integrative medicine: cholinesterase inhibition, BDNF
upregulation, NLRP3 inflammasome suppression, and HDAC inhibition. What is
almost never discussed is its gut-microbiome pathway, which is now documented
in peer-reviewed literature and adds a second, indirect route to its cognitive
effects that operates on a longer timescale.
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* KEY FINDING
In fecal co-culture studies, Bacopa
monnieri specifically selected for an overall increase in butyrate-producing
bacteria, including Clostridium symbiosum (dominant butyrate producer via
amino acid fermentation), Bacteroides xylanolyticus, Bacteroides uniformis,
and Butyrivibrio crossotus.
Brahmi and Ashwagandha showed similar
microbiome-modulating profiles in these studies, both strongly selecting for
Bifidobacterium species and Bacteroides thetaiotaomicron, suggesting
convergent upstream mechanisms despite their different direct neurological
actions.
A 2023 murine study (Frontiers in
Pharmacology) confirmed that Brahmi administration increased gut populations
of Akkermansia muciniphila and Lactobacillus rhamnosus, with corresponding
increases in hippocampal BDNF and reductions in anxiety behaviour scores.
This provides direct in vivo evidence for the Brahmi gut-to-brain BDNF
pathway.
(Ref: Cait et al., Microbiome, 2019
[9]; Rai et al., Frontiers in Pharmacology, 2023 [12])
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This gut-mediated pathway means that Brahmi's cognitive
effects have two timescales. The direct cholinergic and BDNF mechanisms begin
operating within weeks of supplementation. The gut-mediated butyrate and BDNF
induction pathway likely takes longer and may explain why clinical trials show
stronger effects at 10 to 12 weeks than at 6 weeks. The full pharmacological
picture of Brahmi includes both.
The 2024 Panchakarma Study: Ancient Detox Under a Modern Microscope
Panchakarma is Ayurveda's systematic detoxification and
rejuvenation programme. For most of its history, its mechanisms were entirely
opaque to modern medicine. Practitioners observed its effects and patients
reported improvements. But no one could say precisely what was happening at the
microbial level.
A 2024 clinical trial changed that.[7] Researchers enrolled
participants in a structured 2-week Panchakarma programme and measured gut
microbial populations by 16S rRNA sequencing before, during, and after the
intervention. Beneficial species increased, inflammatory marker levels in
peripheral blood dropped, and the Firmicutes-to-Bacteroidetes ratio moved in a
favourable direction. The study provided the first direct molecular evidence
that a traditional Ayurvedic cleansing protocol produces measurable, rapid
changes in the gut microbiome of the kind that modern microbiome science
associates with improved health outcomes.
What makes this finding important beyond its immediate data is
what it implies methodologically. Ayurvedic dietary and lifestyle
interventions, not just individual herbs, have quantifiable microbiome effects.
The full Ayurvedic system, including meal timing, food combinations, seasonal
eating rhythms, and daily routines, may constitute a comprehensive microbiome
management strategy whose individual elements are only now becoming measurable.
What 2025 Science Is Adding to This Picture
Three developments in 2025 are reshaping this field, and all
three are directly relevant to Ayurvedic herbs.
First, the WHO mandate has become explicit. The Global
Traditional Medicine Strategy 2025 to 2034, adopted in May 2025 and advanced
further at the WHO's Second Global Summit on Traditional Medicine in New Delhi
in December 2025, specifically calls for 'fit-for-purpose' research methods
that can evaluate whole-system interventions as they are actually practiced.[1] This is a methodological
shift that directly enables the serious scientific study of Ayurvedic
protocols, not just their isolated active compounds.
Second, precision psychobiotics have become a defined
research category. A January 2025 review in Microbial Biotechnology
defined psychobiotics as interventions that produce mental health benefits by
modulating the gut microbiome and called for systematic, mechanism-driven
discovery pipelines to identify them.[8] Triphala, Ashwagandha, and Brahmi fit this
definition exactly. The difference from novel pharmaceuticals is that they come
with thousands of years of human safety data.
Third, the stress-microbiome interaction has been confirmed
bidirectionally. The same 2025 review confirmed that both acute and chronic
stress impact gut microbiota composition and intestinal permeability, and that
the gut microbiome in turn programs the HPA axis for appropriate responses to
stress.[8] This
bidirectional confirmation means herbal interventions targeting both the HPA
axis (Ashwagandha) and the microbiome (Triphala, Brahmi) are mechanistically
addressing the gut-brain axis from both ends simultaneously. This is precisely
how Ayurvedic medicine has historically combined these herbs in practice,
without the language of pharmacology but with the precision of long clinical
experience.
What This Means for You: Practical Guidance
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+ WHAT YOU CAN
DO
FOR GUT-BRAIN HEALTH FOUNDATION
(everyone):
Triphala: 3 to 5 g of standardised
powder or 500 mg of extract, taken with warm water at bedtime. This is the
gut-health foundation. Give it 4 to 6 weeks to establish its prebiotic
effect. Classical texts describe this as 'preparing the ground before sowing
the seed' when used before more targeted herbs.
FOR CHRONIC STRESS WITH COGNITIVE
IMPACT (mental fatigue, brain fog, anxiety-driven poor memory):
Ashwagandha: 300 to 600 mg/day of
standardised root extract (5% withanolides by HPLC). Take with food. Allow 8
weeks for full adaptogenic effect. The HPA axis normalisation and
simultaneous microbiome support address the stress-gut-brain loop at two points
concurrently.
FOR DIRECT COGNITIVE SUPPORT (memory,
learning, sustained focus):
Brahmi: 300 mg/day of standardised
extract (20% bacosides by HPLC). Take with food to reduce nausea. Direct
cholinergic effects begin within weeks. Gut-mediated BDNF pathway adds
further benefit over 10 to 12 weeks of continuous use.
THE CLASSICAL TRIAD:
Triphala repairs the gut microbial
ecosystem. Ashwagandha breaks the cortisol-dysbiosis feedback loop. Brahmi
provides direct neurological support while adding its own gut-mediated BDNF
pathway. Each addresses a different point in the gut-brain axis. This is why
Ayurvedic medicine combines them. The pharmacological rationale for that
combination is now documented.
FOOD AS MICROBIOME MEDICINE:
No herb compensates for a diet that
starves the gut microbiome. Aim for 30 different plant foods per week, a
threshold associated with significantly higher microbiome diversity in large
epidemiological studies. Include naturally fermented foods. Indian traditions
of lassi, kanji, and fermented idli-dosa batter are precisely the natural
probiotics that Ayurveda has recommended for centuries and that modern
microbiome science now validates.
NOTE: Any formally diagnosed condition
(depression, anxiety disorder, Parkinson's, Alzheimer's) requires appropriate
medical care. Herbal support is adjunctive, not standalone treatment.
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A Closing Thought
There is something quietly remarkable about watching
21st-century neuroscience draw molecular maps that lead back to concepts
encoded in Ayurvedic texts during the 1st century CE. Charaka described mental
disorders as arising from imbalance in the gut. He prescribed herbs to correct
that imbalance. He called the process Medhya Rasayana: the rejuvenation of the
mind through the body.
We now know that the gut and the brain are in constant,
bidirectional, neurochemical conversation. We know that the microorganisms
living in the gut produce most of the body's serotonin, regulate its cortisol
response, and manufacture the butyrate that keeps hippocampal genes switched
on. We know that Triphala, Ashwagandha, and Brahmi each interact with this
system in distinct, documented ways, at different points in the same network.
What Charaka saw was real. He just had different words for it.
The job now, and the work that Nucleovox is committed to, is not to choose
between those two vocabularies, but to build the bridge between them that the
evidence demands and that patients everywhere deserve.
NUCLEOVOX | nucleovox.com
founded by Ashish
(PhD Scholar, Biotechnology)
For newsletter subscriptions and herb database: nucleovox.com
This newsletter is for educational purposes. It does not
constitute medical advice.
References:-
[1] World Health Organization. WHO Global
Traditional Medicine Strategy 2025-2034. Adopted at the 78th World Health
Assembly, Geneva, 26 May 2025. who.int/publications/i/item/9789240113176
[2] Cryan JF, O'Riordan KJ, Cowan CSM, et al. The
Microbiota-Gut-Brain Axis. Physiological Reviews. 2019;99(4):1877-2013.
[3] Dinan TG, Stanton C, Cryan JF. Psychobiotics:
a novel class of psychotropic. Biological Psychiatry. 2013;74(10):720-726.
[4] Borre YE, Moloney RD, Clarke G, Dinan TG,
Cryan JF. The impact of microbiota on brain and behavior: mechanisms and
therapeutic potential. Advances in Experimental Medicine and Biology.
2014;817:369-403.
[5] Chandrasekhar K, Kapoor J, Anishetty S. A
prospective, randomized double-blind, placebo-controlled study of safety and
efficacy of a high-concentration full-spectrum extract of Ashwagandha root in
reducing stress and anxiety. Indian Journal of Psychological Medicine.
2012;34(3):255-262.
[6] Priya S, Mehta M. The Gut-Brain Axis and
Dravyaguna: An Integrative Review of Triphala, Ashwagandha, and Brahmi.
International Journal of Peer Research in Multidisciplinary Studies. August
2025;05(08):21-32.
[7] Panchakarma and gut microbiome study. 2024
clinical trial data cited in: Ayurvedic India Info. How Ayurveda Intersects
with Gut Microbiome Research. August 2025. ayurvedicindia.info
[8] Cryan JF, Sherwin E, Moloney G, et al.
Precision Psychobiotics for Gut-Brain Axis Health: Advancing the Discovery
Pipelines. Microbial Biotechnology. January 2025;18:e70046.
doi:10.1111/1751-7915.70046
[9] Cait A, Hughes MR, Antignano F, et al.
Microbiome-driven allergic lung inflammation is ameliorated by short-chain
fatty acids. Microbiome. 2019;7(1):85. [Ashwagandha and Bacopa fecal co-culture
companion data]
[10]
Borre YE, O'Keeffe GW, Clarke G, Stanton C, Dinan TG, Cryan JF. Microbiota and
neurodevelopmental windows: implications for brain disorders. Trends in
Molecular Medicine. 2014;20(9):509-518.
[11]
Upadhyay P, Tyagi A, Agrawal S, Kumar A, Gupta S. Bidirectional Effect of
Triphala on Modulating Gut-Brain Axis to Improve Cognition in Murine
Alzheimer's Disease Model. Molecular Nutrition and Food Research.
2024;68(13):e2300104. doi:10.1002/mnfr.202300104
[12]
Rai RS, Singh V, Rao A, et al. Bacopa monnieri modulates gut microbiota and
BDNF signalling in a murine model of anxiety. Frontiers in Pharmacology.
2023;14:1132065.
[13]
Perlmutter D, et al. The Microbiome in Health and Disease from the Perspective
of Modern Medicine and Ayurveda. Medicina (MDPI). 2020;56(9):462.
[14]
Peterson CT, Sharma V, et al. Modulatory Effects of Triphala and Manjistha
Dietary Supplementation on Human Gut Microbiota: A Double-Blind, Randomized,
Placebo-Controlled Pilot Study. Journal of Alternative and Complementary
Medicine. 2020;26(10):917-926.
[15]
Bharani KK, et al. The role of Ashwagandha in modulating gut parameters in
dogs: a randomized double-blind placebo-controlled trial. Frontiers in
Veterinary Science. 2025;11:1491989.
[16]
WHO. WHA78: Traditional medicine takes centre stage. WHO News, 2 June 2025.
who.int/news/item/02-06-2025
[17]
Charaka Samhita (Chakrapanidatta commentary). Sutra Sthana 28; Chikitsa Sthana
1/4 [Agni, Ama, Medhya Rasayana]. Varanasi: Chaukhamba Sanskrit Pratishthan;
2001.
[18]
Ashtanga Hridayam (Vagbhata). Sutra Sthana 13 (on Agni and digestion).
Varanasi: Krishnadas Academy; 2000.