Herbal interventions to support the bi-directional connection
The gut-brain axis (GBA) represents a dynamic, bidirectional communication network, linking the central nervous system (CNS) and the gastrointestinal (GI) tract. This intricate system encompasses neural (vagus nerve), hormonal, immune, and microbial pathways. Increasing research has highlighted the critical role this axis plays in mood regulation, stress resilience, cognitive function, and gastrointestinal health.
For integrative health practitioners, understanding the GBA is essential in addressing conditions of IBS, anxiety, depression, brain fog, and neuroinflammatory disorders. Beyond diet and lifestyle, herbal medicine offers a powerful toolkit to support both ends of the axis, enhancing outcomes in holistic clinical practice.
Core pathways: At the neuroanatomical level, the vagus nerve serves as a critical communication superhighway, transmitting sensory and motor signals that influence both gut function and brain activity. This includes feedback on gut motility, satiety, and even emotional regulation.
The endocrine pathway involves the secretion of key hormones, most notably cortisol, which is central to the body's stress response via the hypothalamic-pituitary-adrenal (HPA) axis, and serotonin, of which about 90–95% is produced in the gut. These hormones play pivotal roles in modulating mood, stress perception, digestion, and circadian rhythm.
The immune system also plays a fundamental role in GBA integrity; increased gut permeability, often referred to as “leaky gut”, can allow immune-activating substances like lipopolysaccharides (LPS) to enter circulation, triggering systemic inflammation and affecting the blood-brain barrier, potentially contributing to neuroinflammation and neurodegeneration.
Equally crucial is the influence of the gut microbiota: trillions of commensal bacteria residing in the gut that produce neuroactive compounds such as gamma-aminobutyric acid (GABA), short-chain fatty acids (SCFAs), and tryptophan metabolites that affect mood, cognition, and immune balance.
Clinically, disruptions in any of these pathways can have widespread health implications. Dysbiosis, or microbial imbalance, and compromised intestinal barrier function are increasingly associated with mental health issues like anxiety and depression, as well as neurodegenerative conditions such as Alzheimer’s disease. Furthermore, chronic psychological stress has been shown to negatively impact gut motility, increase intestinal permeability, and shift microbial composition toward a pro-inflammatory state, perpetuating a harmful feedback loop. Conditions such as small intestinal bacterial overgrowth (SIBO), inflammatory bowel disease (IBD), and mood disorders all illustrate the importance of maintaining GBA integrity for overall health. Understanding these pathways allows practitioners to approach treatment holistically addressing gut, brain, and immune health together rather than in isolation.
Herbal allies for gut health: A wide array of medicinal herbs can strategically support both the gut and brain components of the gut-brain axis. Collectively these enhance resilience, reduce inflammation, and restore functional balance.
For gut health, demulcent herbs like Slippery Elm (Ulmus rubra) and Marshmallow Root (Althaea officinalis) are foundational. Slippery Elm contains mucilage that coat and soothe the irritated mucosal linings of the gastrointestinal tract. This makes it particularly useful in conditions like gastroesophageal reflux disease (GERD) and irritable bowel syndrome (IBS). Marshmallow Root offers similar mucosal protection and is additionally immune-modulatory, helping to reduce localised inflammation and support gut barrier integrity. This is essential in preventing immune activation and systemic inflammation associated with “leaky gut.”
Chamomile (Matricaria chamomilla) serves a dual role as a carminative and mild anxiolytic. This makes it particularly well-suited for individuals experiencing gut distress linked to stress, such as stress-related IBS. Its ability to calm nervous tension while easing spasmodic digestive symptoms makes it gentle yet effective. Liquorice (Glycyrrhiza glabra), particularly in its deglycyrrhizinated form (DGL), promotes mucosal healing and reduces inflammation. This is often used in addressing ulcers, gastritis, and even H. pylori infections. For microbial imbalances, such as dysbiosis or small intestinal bacterial overgrowth (SIBO), berberine-containing herbs like Berberis vulgaris offer potent antimicrobial properties and help rebalance gut flora. This makes them invaluable in antimicrobial protocols and pathogen overgrowth management.
Kawakawa (Piper excelsum), a New Zealand native herb, offers effective support for the gastrointestinal system through its anti-inflammatory and mild analgesic properties, helping to ease digestive discomfort and cramping. Ginger (Zingiber officinale) has carminative and digestive stimulant actions that improve gastric motility, alleviates bloating, nausea, and indigestion, and reduces gut inflammation through its antioxidant actions. Its influence on serotonin receptors also supports gut-brain axis balance, particularly under stress. Peppermint (Mentha × piperita), known for its antispasmodic effects, relaxes smooth muscle in the digestive tract, providing relief from pain, gas, and bloating, especially in IBS. The menthol component calms the enteric nervous system, making it a powerful agent for addressing functional digestive disorders.
Herbal allies for brain health: On the brain and nervous system side of the axis, herbs with neuroprotective, adaptogenic, and anti-inflammatory actions can profoundly influence mood, cognitive function, and stress adaptation. Ashwagandha (Withania somnifera) is one of the most well-researched adaptogens, known to modulate cortisol, reduce anxiety, and enhance cognitive performance. This makes it a cornerstone for stress-related disorders. Bacopa (Bacopa monnieri) is a traditional Ayurvedic nootropic that improves memory, learning capacity, and mental clarity, while also exerting calming effects on the nervous system. Lion’s Mane (Hericium erinaceus), a medicinal mushroom, has gained significant attention for its ability to stimulate nerve growth factor (NGF), supporting both cognitive regeneration and repair of gut mucosa, which shares embryological origins with neural tissue.
Gotu Kola (Centella asiatica) acts as a circulatory and nervous system tonic, enhancing microcirculation, reducing neuroinflammation, and addressing symptoms like brain fog and anxiety. It also aids tissue repair, making it supportive of both neural and intestinal healing. Finally, Rhodiola (Rhodiola rosea) is another powerful adaptogen that enhances mental stamina, combats stress-induced fatigue, and improves mood regulation, particularly in cases of burnout and cognitive exhaustion. Rhodiola is an endangered herb which means it is not always available and should be used with careful consideration.
For practitioners, addressing the GBA holistically involves:
- Reducing gut inflammation and permeability
- Balancing microbial communities
- Regulating HPA axis dysfunction
- Promoting neurogenesis and cognitive function.
Always assess for contraindications (eg liquorice in hypertension) and interactions (eg with antidepressants or GI medications).
Conclusion: The gut-brain axis presents a powerful framework for treating a range of interconnected disorders. Herbs offer a safe and effective modality to support the physiology of both systems while addressing root causes. It is crucial for practitioners to align with the GBA using botanicals to foster resilience, mood stability and long-term wellbeing.