A balanced and nutrient-rich diet not only enhances physical health but also boosts mood and mental well-being. Numerous studies published in Psychoneuroendocrinology (2022) demonstrate a strong correlation between the digestive system and the brain, referred to as the gut-brain axis. This is a bidirectional communication system linking the central nervous system to the enteric nervous system (a complex network of neurons in the gut). In fact, stress reduction not only relaxes the mind but also alleviates gastrointestinal symptoms such as constipation.
The Strong Connection Between the Gut and the Brain
When we think about food, the stomach can already begin secreting digestive juices. Moreover, the gut is sensitive to emotions, an effect of the gut-brain axis (Park & Gao, 2024). According to Maya Shetty (2024), published in Stanford Lifestyle Medicine, recent studies continue to affirm the significant role of the gut-brain axis in regulating digestive and emotional functions. For instance, when we think about food, the brain activates the vagus nerve, a primary link between the brain and the gut, preparing the stomach for digestion. This illustrates the two-way relationship between the central nervous system and the enteric nervous system.
Stress is a crucial but often overlooked factor that causes gut issues. According to Harvard Health, “Stress can exacerbate stomach pain, and vice versa.” Taking care of emotional health and reducing stress not only benefits the mind but can also significantly improve gut symptoms, sometimes more effectively than conventional medical treatments.
The “First” Nervous System
The nervous system is divided into two parts:
• Somatic nervous system: Controls conscious actions like chewing or walking.
• Autonomic nervous system: Regulates automatic functions such as breathing, heartbeat, sweating, and shivering.
The autonomic nervous system adjusts the body by speeding up or slowing down its functions. When faced with danger, the sympathetic system triggers the “fight or flight” response, increasing heart rate and rapid breathing. When relaxed, the parasympathetic system helps the body rest, improving digestion, nutrient absorption, and reducing inflammation.
This phase is referred to as “rest and digest.” Both the sympathetic and parasympathetic systems influence digestion, which is why stress often leads to digestive issues, while relaxation supports efficient digestion.
The Gut as the “Second Brain”
In addition to the “primary” nervous system, the gut has a separate nervous system called the enteric nervous system, which stretches from the esophagus to the colon. Known as the “second brain,” it comprises 100 million neurons communicating via neurotransmitters, functioning similarly to the primary nervous system.
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Figure 1. Interaction of the Gut-Brain Nervous System
The enteric nervous system receives signals from both the sympathetic and parasympathetic systems, helping regulate the body’s pace (Figure 1). It can also operate independently, like a standalone “brain.” The enteric nervous system is crucial for digestion. After eating, its neurons command intestinal muscles to contract, moving food along. This system is also connected to the immune system in the gut, protecting the body from bacteria and infections while signaling the brain about the gut’s condition.
The Gut-Brain Axis
The gut-brain axis is the link between the gut and the brain, illustrating how signals flow from the brain to the gut and vice versa (Figure 2). Research indicates that the enteric nervous system can send signals to the brain via the vagus nerve, regulating emotions and stress responses.
During “fight or flight” stress responses, the body halts digestion to focus on physical reactions. A study in Gastroenterology (2015) revealed that stress could reduce blood flow to the digestive system, slowing digestion and causing symptoms like stomach pain or nausea.
Figure 2. The Relationship Between the Gut-Brain Axis
Conversely, digestive issues such as inflammation or irritable bowel syndrome (IBS) can elevate stress levels and negatively affect mood. Nikolova et al. (2021) found that individuals with chronic digestive diseases have a higher risk of anxiety and depression, linked to changes in gut microbiota and neurotransmitter production, such as serotonin.
How Stress and Emotions Affect the Gut
Stress and strong emotions can profoundly impact the digestive system due to the gut-brain connection. Feelings such as fear, anxiety, or anger can disrupt digestion, speeding it up or slowing it down excessively, leading to stomach pain, bloating, or bacterial infiltration into the gut lining. This may increase gut inflammation and alter gut microbiota, contributing to conditions such as Crohn’s disease, colitis, IBS, and gastroesophageal reflux disease (GERD).
When these issues occur, they signal the brain, increasing stress and affecting mood, creating a vicious cycle of stress and digestive problems. Recent research also indicates that changes in inflammation or gut microbiota not only affect the brain but are also linked to diseases such as depression and heart disease. A study by Peter Holzer et al. (2022) in Frontiers in Psychology emphasized that the effects of stress on gut microbiota may increase the risk of psychological and cardiovascular diseases.
How the Mindful Gut Approach Can Help
The Mindful Gut approach (Figure 3) includes various goals to improve digestive and mental health by paying attention to eating habits and bodily sensations, enhancing gut health, and directly impacting the gut-brain axis.
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Figure 3. The Mindful Gut Approach
This method emphasizes balanced nutrition, or “kitchen confidence,” improving the relationship between the brain and the gut. Two essential food groups for gut and brain health are fiber and fermented foods. Fiber is abundant in fruits and vegetables, but most people fall short of the recommended intake. Fermented foods like yogurt, kefir, kombucha, and miso are also beneficial for digestion. Recent studies support the role of fiber-rich diets, such as those with inulin, FOS, and fermented foods, in improving gut health and reducing stress, helping alleviate issues like IBS and colitis.
A study by Wang et al. (2022) in Frontiers in Nutrition revealed that diets rich in fiber and probiotics could reduce inflammation and support gut microbiota balance.
Moreover, “trusting your gut” involves listening to and understanding natural body signals like hunger, fullness, bloating, or discomfort while respecting your intuition. This helps in making decisions aligned with personal values and goals. However, stress significantly impacts gut health. The brain-gut connection shows that when the mind is stressed, the gut is easily affected, and vice versa. In conclusion, effective stress management is key to maintaining gut health balance.
References
Gut-Brain Axis – Amanda Sauceda https://amandasauceda.com/gut-brain-axis/
Maya Shetty, BS. More Than a Gut Feeling: How Your Microbiome Affects Your Mood
in Cognitive Enhancement, Gut Health, Healthful Nutrition, Mental Health https://longevity.stanford.edu/lifestyle/2024/04/08/more-than-a-gut-feeling-how-your-microbiome-affects-your-mood/
Nikolova VL, Smith MRB, Hall LJ, Cleare AJ, Stone JM, Young AH. Perturbations in Gut Microbiota Composition in Psychiatric Disorders: A Review and Meta-analysis. JAMA Psychiatry. 2021;78(12):1343–1354. doi:10.1001/jamapsychiatry.2021.2573
Holzer P (2022) Gut Signals and Gut Feelings: Science at the Interface of Data and Beliefs. Front. Behav. Neurosci. 16:929332. doi: 10.3389/fnbeh.2022.929332
Tan H-E (2023) The microbiota-gut-brain axis in stress and depression. Front. Neurosci. 17:1151478. doi: 10.3389/fnins.2023.1151478
Park KJ and Gao Y (2024) Gut-brain axis and neurodegeneration: mechanisms and therapeutic potentials. Front. Neurosci. 18:1481390. doi: 10.3389/fnins.2024.1481390
Wang Z, Liu S, Xu X, Xiao Y, Yang M, Zhao X, Jin C, Hu F, Yang S, Tang B, Song C and Wang T (2022) Gut Microbiota Associated With Effectiveness And Responsiveness to Mindfulness-Based Cognitive Therapy in Improving Trait Anxiety. Front. Cell. Infect. Microbiol. 12:719829. doi: 10.3389/fcimb.2022.719829