The Gut–Brain Connection: How Stress Impacts Gut Health and Mental Health
By: Sarah Khan - Functional Nutritionist - https://www.sarahfunctionalnutritionist.com/
A Functional Medicine Perspective on Healing the Gut–Mind Axis
Introduction
If you’ve ever felt “butterflies” before a big event or noticed your digestion change during stress, that’s your gut–brain connection in action.
In functional medicine, we recognize that gut health and mental health are intricately linked. Your digestive system and brain communicate constantly through a complex network of nerves, hormones, and immune signals. When the gut is imbalanced, mood, focus, and stress resilience often suffer.
The Gut–Brain Axis Explained
Your gut is home to trillions of bacteria known as the gut microbiome. These microbes produce key neurotransmitters, including serotonin and GABA, that regulate mood and emotional well-being. In fact, about 70-90% of your body’s serotonin is made in the gut, not the brain.
When your microbiome is disrupted (a condition called gut dysbiosis), it can lead to inflammation, nutrient malabsorption, and changes in neurotransmitter production, contributing to anxiety, depression, and brain fog.
How Stress Disrupts Gut Health
Chronic stress alters nearly every aspect of digestion. When your body is stuck in “fight or flight” mode, it redirects energy away from the gut, resulting in:
Slower digestion or IBS-like symptoms
Reduced stomach acid and enzyme output (poor digestion, bloating)
Weakened gut lining (“leaky gut”)
Imbalanced gut bacteria
Over time, this stress–gut cycle fuels inflammation, creating a vicious loop: stress damages the gut, and a damaged gut in turn increases stress signals to the brain.
The Gut’s Role in Mental Health
Emerging research shows that people with anxiety and depression often have lower microbial diversity. Beneficial bacteria, such as Lactobacillus and Bifidobacterium, produce short-chain fatty acids (SCFAs) that help calm inflammation and support brain health.
When these bacteria are depleted, your ability to produce mood-balancing chemicals declines, leading to irritability, fatigue, or mood swings. Healing the gut can often improve these symptoms naturally.
A Functional Medicine Approach to Restoring Balance
In my practice, I use a root-cause, nourish-first approach to restore the gut–mind connection. This means addressing the underlying drivers—such as inflammation, blood sugar imbalances, and chronic stress, rather than merely masking symptoms.
Here’s where we start:
1. Nourish the Microbiome
Eat a variety of colorful, fiber-rich foods (veggies, fruits, legumes, whole grains).
Include fermented foods like sauerkraut, kefir, or miso.
Add polyphenol-rich foods, such as berries, green tea, and olive oil.
2. Balance Blood Sugar
Stable blood sugar supports a calm, focused mind. Include protein, healthy fats, and fiber at each meal, and limit your intake of refined sugars and caffeine.
3. Reduce Gut Inflammation
Support gut repair with nutrients such as L-glutamine, omega-3 fatty acids, and zinc carnosine. Avoid processed and inflammatory foods to allow the gut lining to heal.
4. Regulate the Stress Response
Chronic stress can’t be healed by supplements alone. Try deep breathing, gentle movement, nature walks, and adaptogens like ashwagandha or rhodiola to lower cortisol and improve resilience.
5. Rebalance the Gut–Brain Axis
Targeted probiotics (Lactobacillus rhamnosus GG, Bifidobacterium longum) can reduce anxiety and improve mood. Pair them with restorative sleep and mindful movement for the best results.
The Takeaway
Your gut and brain are in constant dialogue. When the gut is inflamed, the brain suffers—but when you heal the gut, your mood, energy, and focus often follow.
Through functional nutrition, lifestyle changes, and stress management, it’s possible to restore both gut and mental health, naturally and sustainably.
If you’re ready to feel more balanced from the inside out, Sarah Khan can help you get started. As a functional nutritionist, she works with you to uncover the root causes of imbalance and build a personalized plan for sustainable healthy habits. Visit sarahfunctionalnutritionist.com to learn more and schedule a free 15-minute discovery call!
Jessica Thomas, LMHC is a Haitian-American and licensed mental health therapist for New York, Florida, and Washington D,C. I specialize in working with adults striving to improve their mental health by breaking generational cycles of trauma, burnout, and self-neglect. Together we’ll work through learning to prioritize yourself, stop carrying it all, and step out of living in survival mode and into a life that feels yours. Visit www.mymindsetnyc.com to learn more and book a 20-minute consultation with her here.
