Skarp
Gut-Brain Axis Essentials: How Your Digestion Shapes Your Mood and Mind
This course explores the surprising two-way communication between your digestive system and your brain. You will learn how the gut, microbiome, nerves, hormones, and immune system interact to influence stress, mood, cognition, and mental health—and what everyday choices may support a healthier gut-brain connection.
Course Content
8 modules · 2h total
Module 1: Meet Your Second Brain – The Gut-Brain Axis Overview
Introduce the gut-brain axis as a continuous, two-way communication network linking the digestive system and the brain, and why it matters for mood, stress, and overall mental health.
Module 2: Nerves in Your Belly – The Enteric Nervous System and Vagus Nerve
Explore the ‘second brain’ in your gut—the enteric nervous system—and the vagus nerve as a primary highway carrying signals between the gut and the brain.
Module 3: Microbiome 101 – Your Gut’s Invisible Community
Introduce the gut microbiota, how microbes live in the digestive tract, and the emerging science on how they influence brain function and behavior.
Module 4: Chemical Messengers – Neurotransmitters, Hormones, and the HPA Axis
Examine how chemical messengers like serotonin, GABA, and stress hormones connect gut activity to mood, anxiety, and cognitive function.
Module 5: Inflammation and Immunity – When the Gut Talks Through the Immune System
Explore how the immune system and inflammatory signals serve as another channel in the gut-brain dialogue, influencing mental health when gut balance is disturbed.
Module 6: Gut-Brain Axis in Mental Health – Depression, Anxiety, and Beyond
Connect the biology of the gut-brain axis to specific mental health conditions, focusing on depression, anxiety, and emerging links to cognition and neurodegeneration.
Module 7: Psychobiotics and Microbiome-Targeted Therapies – Promise and Caution
Introduce psychobiotics and other microbiome-focused strategies as potential tools for supporting mental health, highlighting what is known, what is experimental, and why high-quality evidence matters.
Module 8: Everyday Levers – Diet, Lifestyle, and Supporting a Healthy Gut-Brain Axis
Translate the science into practical, evidence-informed strategies related to diet, sleep, stress management, and physical activity that may support gut and mental health, while avoiding overhyped claims.
Read the Textbook
Read every chapter for free, right here in your browser.
When people say **“trust your gut”**, they’re not just being poetic.
Your digestive system and your brain are linked by a **continuous, two-way communication network** called the **gut–brain axis**.
**Working definition (2026, widely used in current research):** > The **gut–brain axis** is the **bidirectional communication system** connecting the **central nervous system (CNS)** and the **gastrointestinal tract**, involving the **enteric nervous system (ENS)**, **autonomic nervous system (ANS)**, **endocrine (hormone) system**, **immune system**, and **gut microbiota**.