What Are You Feeding Your Second Brain – The Microbiome?
- Jul 30, 2025
- 4 min read
Meg Marie O'Rourke is a Registered Dietitian/ Functional Nutritionist with over 20 years of experience. She is the founder of Harmony with Food™ and producer of the Harmony With Food™ radio, based out of iHeart Providence. Meg's show has been syndicated to 6 other stations throughout the United States.
Did you know that your body has two brains? The first is the one you’re thinking with right now. The second? It’s in your gut, and scientists now know it plays a powerful role in how you feel, think, and function. Called the enteric nervous system, this “second brain” is home to over 100 million nerve cells and trillions of microbes, all working together to influence your mood, anxiety, depression, memory, immunity, and decision-making.
If you’re feeding your gut well, your brain will reap the benefits. If not, your microbiome might be sending distress signals upstairs.
Let’s dig into how the gut-brain connection works and what to eat to support it.
What is the gut-brain axis?
The gut-brain axis refers to the two-way communication system between your gastrointestinal system and your central nervous system. This is not metaphorical; your gut and brain are physically connected through the vagus nerve, and they are constantly exchanging information.
Microbes in your gut produce many of the same neurotransmitters found in your brain, like serotonin, dopamine, and GABA, which help regulate mood, sleep, and cognition. In fact, about 90% of your body’s serotonin (a feel-good hormone) is produced in your gut.
When your microbiome is out of balance (a state called dysbiosis), it can contribute to symptoms like:
Brain fog
Anxiety and depression
Digestive issues
Fatigue
Food sensitivities
Foods that harm your microbiome
Let’s be honest: most modern diets don’t support optimal brain-gut health.
Here are a few common culprits that can throw your microbiome out of balance:
Ultra-processed foods: Chips, packaged snacks, and fast food contain additives (food dyes) and emulsifiers that harm beneficial gut bacteria.
Refined sugars: Sugar feeds harmful bacteria and fungi (Aka yeast), leading to inflammation and mood swings. (Just as women can get vaginal yeast infections, both men and women can have yeast in the gut)
Artificial sweeteners: Some studies suggest that these may disrupt the microbiome and worsen insulin resistance. Plus, they can cause weight gain.
Excess alcohol: Can increase gut permeability (“leaky gut”) and contribute to mood imbalances.
What to eat for a healthy brain-gut connection
Feeding your microbiome well isn’t about perfection; it’s about adding more of the good stuff. Here are key gut-loving foods to support your second brain:
Prebiotic-rich foods
Prebiotics are fibers that feed beneficial bacteria.
Garlic
Onions
Leeks
Asparagus
Bananas (especially green)
Probiotic-rich foods
These contain live bacteria that help rebalance your gut:
Yogurt with live cultures
Kefir
Sauerkraut
Kimchi
Miso
Tempeh
Polyphenols
These plant compounds help reduce inflammation and feed healthy microbes:
Berries
Olive oil
Green tea
Dark chocolate (70%+ cocoa)
Whole plant foods
Diverse fiber = Diverse microbiome = More resistant brain health
Aim for 30+ plant types per week (fruits, veggies, grains, legumes, herbs)
Why it matters: The gut’s impact on mental health
Modern research continues to confirm it: Your gut health directly influences your emotional and cognitive wellbeing.
Studies have shown that:
People with depression often have a less diverse microbiome
Certain probiotics (sometimes called psychobiotics) may reduce anxiety symptoms
Diets high in fiber and fermented foods can lower markers of inflammation and improve cognition.
Your second brain might just be the missing piece in your wellness puzzle.
Takeaway: Trust your gut and feed It Wisely
If you’re struggling with brain fog, mood swings, or low energy, the answer may not be just in your head; it could be in your gut. Nourishing your microbiome with whole, real foods isn’t just good for digestion; it’s essential for cognitive clarity, emotional balance, and long-term brain health.
How Meg can help
Want personalized support for your gut-brain journey? At Harmony With Food™, Meg’s Biounique Boutique™ offers science-backed strategies tailored to your individual needs.
Her motto? “Test, Don’t Guess.”
Book a free 45-minute call to discover which lab tests might reveal the root cause of your symptoms.
Click here to schedule your session.
The Harmony With Food Podcast: Listen here.
Get started today with Meg’s free, gut-supporting tools:
Healthy 40+ Snack Suggestions
Microbiome Sample Test
Food Sensitivity Sample Test
Micronutrient Sample Test
Explore these more here.
Follow me on Facebook, Instagram, LinkedIn, and visit my website for more info!
Meg Marie ORourke, Registered Dietitian/ Functional Nutritionist
Meg Marie O'Rourke, Registered Licensed Dietitian Nutritionist, is the founder of Harmony With Food™, a health and wellness practice dedicated to empowering individuals to achieve their health goals through personalized nutrition.
The Bio-Unique Boutique™ Program, where Meg says "test, don't guess," is just one of her programs offered. With a passion for helping others navigate their unique health challenges, Meg specializes in medical nutrition therapy and functional nutrition, focusing on the root causes of issues such as weight loss resistance, gastrointestinal problems, and chronic fatigue.
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