man standing holding bowl of food looking stressed

The gut, often referred to as the "second brain," harbors trillions of bacteria and other microorganisms that play a vital role in maintaining overall health and uniquely affect mental health. Keith Scharf, DO, FACS, FASMBS, director of bariatric surgery at Loma Linda University Health, shares the intricate relationship between the gut and brain.

What really is gut health?

Scharf says there is not a strict definition of gut health, but the concept refers to the function of the gastrointestinal (GI) tract and its role in the absorption of nutrients, digestion, elimination of waste, immune function, and mental health.

The gut is home to a diverse community of microorganisms collectively known as the gut microbiota. Trillions of microbiota line the GI tract and help produce a barrier that assists with the absorption of nutrients, sends signals to the brain, defends against infections, and helps with immune tolerance, as studies show up to 80% of immune cells live in the GI tract. The signals sent from the GI tract to the brain can affect mood, cognition, and behavior.

Connection to mental health

“The brain and the gut are intimately connected and send signals back and forth,” Scharf says. “Emerging evidence suggests that imbalances in the gut microbiota can disrupt this communication, potentially leading to mental health disorders such as anxiety, depression, and even neurodevelopmental conditions.”

The gut microbiota produces and interacts with various compounds, including neurotransmitters like serotonin and gamma-aminobutyric acid (GABA), playing crucial roles in regulating mood and emotions. Serotonin, known as the "happy hormone," is primarily produced in the gut and influences mood, sleep, and appetite. Scharf says disruptions in the gut microbiota can interfere with the production and signaling of these neurotransmitters, contributing to mental health disorders. Studies have found higher rates of depression and anxiety in patients with GI disorders like irritable bowel syndrome and ulcerative colitis.

What can you do?

  1. A balanced diet: Consume a diverse range of fruits, vegetables, whole grains, and fermented foods to incorporate fiber and omega-3 fatty acids.
  2. Probiotics and prebiotics: Incorporate probiotic-rich foods like yogurt, pickles, kimchi, and prebiotic foods, garlic, onions, bananas, etc., to nourish and promote the growth of beneficial gut bacteria.
  3. Reduce stress: Chronic stress can disrupt the gut-brain axis. Engage in stress-reducing activities and regular exercise to promote a healthy gut and mental well-being.
  4. Limit antibiotic use: While antibiotics are crucial for treating bacterial infections, their overuse can negatively impact the gut microbiota. Use antibiotics judiciously and consider probiotic supplementation during and after antibiotic treatment.

Consult a healthcare provider to discuss your symptoms before adding any medications or supplements into your rotation. Some symptoms to take note of include:


  • Bloating
  • Abdominal pain
  • Constipation
  • Diarrhea
  • Gas
  • Lactose or gluten intolerance


  • Fatigue
  • Acne
  • Mood disturbances like difficulty concentrating, anxiety, or depression

“Though we do not have a strict medical definition for what is a healthy gut, there is enough evidence to suggest a link between the gut, brain, and overall well-being,” Scharf says. “The basic tenets of managing stress, eating a well-balanced diet, achieving adequate sleep at night, and avoiding toxic substances, like tobacco and alcohol, can help promote an overall healthy body and mind.”

Make an appointment with your primary care provider to discuss your symptoms and explore services offered at the Digestive Disease Center.