The Gut-Your Body’s Second Brain

If you have ever felt “butterflies in your stomach” when nervous or excited, or if you have “gone with your gut” to decide, you are likely receiving signals from your second brain hidden in the walls of your digestive system, i.e., the gut!  

The sensations of ‘gut feeling’ or ‘butterflies in your stomach’ and the ‘gut-wrenching’ roller coaster rides or feeling nauseous before giving a presentation emanate from the belly, indicating that your brain is connected to your gut. The fear of public speaking slows down or speeds up digestive procedures, causing diarrhea, abdominal pain, and other symptoms. 

The gut-brain connection works in both directions, so gastrointestinal (GI) issues such as abdominal cramps, loose stools, and heartburn can result in stress and anxiety, and strategies that help you deal with the stressors in your life can ease your digestive discomforts.

In times of danger, the “fight or flight” response of the central nervous system (CNS) involving the brain is triggered. At the same time, the enteric nervous system (ENS) of your intestines responds by slowing down or stopping the process of digestion to divert your body’s energy to the threat at hand. 

Researchers have found that pain and nausea involve similar nerve centers. The ENS depends on the same type of neurons (nerve cells) and neurotransmitters (chemicals that pass along nerve cell signals) that are found in the CNS. Hence, the gut is called the “second brain.” 

One of the neurotransmitters is serotonin that contributes to feelings of happiness and helps control your body clock. Interestingly, a large proportion of serotonin is produced in the gut. Gut microbes also produce a neurotransmitter called gamma-aminobutyric acid (GABA), which helps control feelings of anxiety and fear.

The ENS comprises contains 500 million neurons, which are connected to your brain through nerves in your nervous system, lining the gastrointestinal tract and extending along the food pipe (esophagus), stomach, intestines, and rectum. The vagus nerve is one of the biggest nerves connecting your gut and brain. It sends signals in both directions.

When you see something tasty, the brain signals the gut to prepare for the incoming food. Messages travel from the gut to the brain, too, and therefore, when we fall ill after eating something, we instinctively avoid the food and even the place where we ate it.

The Gut-Brain Axis

The communication between the gut and the brain is called the gut-brain axis and plays a vital role in maintaining our mental and overall health. 

The ENS may trigger big emotional shifts experienced by people coping with irritable bowel syndrome (IBS) and functional bowel problems such as diarrhea, constipation, bloating, pain and stomach upset. Many individuals with anxiety and depression have functional bowel problems at some point.

Gut microbes are linked to cognitive functions- thinking and memory

Your second brain can alter your health, mood, and even the way you think. Gut bacteria can ainfluence the brain and the CNS by controlling inflammation and hormone production.

Your gut microbes produce lots of short-chain fatty acids (SCFA) such as butyrate, propionate and acetate. SCFA affects brain function in several ways, such as reducing appetite, and regulate the gut-brain axis. Changes in the counts of Barnesiella, Lachnospiraceae, Akkermansia, and Sutterella can affect cognition, especially among middle-aged adults. 

Your gut-brain axis is also connected through the immune system. Gut microbes play an important role in your immune system by controlling what is passed into the body and what is excreted. If your immune system is switched on for too long, it can lead to inflammation, which is associated with brain disorders like Alzheimer’s disease.

Lipopolysaccharide (LPS) is an inflammatory toxin made by gut bacteria. When the gut barrier becomes leaky, LPS can pass into the blood and lead to  brain disorders including severe dementia, depression, and schizophrenia.

What Can You Do To Improve Your Gut-Brain Health?

Consume more prebiotics and probiotics

Gut bacteria affect brain health, so changing your gut bacteria to restore the microbial balance in the intestines may improve your brain health.

Prebiotics, which are typically fibers that are fermented by your gut bacteria, may also affect brain health. Researchers found that that taking a prebiotic called galactooligosaccharides for three weeks significantly reduced the amount of stress hormone in the body, called cortisol.

Probiotics are live bacteria that impart health benefits when consumed. Probiotics that affect the brain are often referred to as “psychobiotics” and can improve symptoms of stress, anxiety and depression and treat neurological disorders, such as  Parkinson’s disease, Alzheimer’s disease, and autism.

One small study of people with irritable bowel syndrome (IBS) and mild-to-moderate anxiety or depression found that taking a probiotic called Bifidobacterium longum NCC3001 for six weeks significantly improved symptoms.

A study showed that probiotic intake in the form of a mixture of three Lactobacillus and Bifidobacteria strains for eight weeks significantly reduced symptoms of depression and neuroinflammation.

Increase intake of gut-booster foods for better mental health

Gut-booster foods can improve your mental health They include the following: 

• Omega-3 fatty acids: They are predominantly found in fish. Studies have reported that omega-3s can increase good bacteria in the gut and lower the risk of brain disorders. Flax seeds, walnuts, sardines, salmon, and mackerel are rich in Omega-3s. 
• Fermented foods: Kefir, yogurt, cheese, kimchi, and sauerkraut contain healthy microbes such as lactic acid bacteria and can alter brain activity.
• High-fibre foods: Nuts, seeds, whole grains, legumes, beans, nuts, oats, vegetables, and fruits contain prebiotic fibers that are good for your gut bacteria. They can reduce stress hormone in humans. Eating fibre improves also improves mood and memory and decreases oxidative stress and inflammation by supporting good microbes. 
• Polyphenol-rich foods: Green tea, cocoa, coffee and olive oil contain polyphenols, which are plant chemicals that are digested by your gut bacteria. Polyphenols increase healthy gut bacteria and may improve cognition.
• Tryptophan-rich foods: Tryptophan is a protein molecule that is converted into the neurotransmitter serotonin. Foods that contain high amounts of tryptophan include cheese, eggs, and turkey.
• Vitamin D: Vitamin D regulates your microbiota and reduces gastrointestinal inflammation. Sources of vitamin D include tuna, egg yolks, orange juice, fortified milk, and salmon.
• Protein. Proteins contain nitrogen, which limits the number of bad bacteria in the gut microbiome.  Protein intake may also reduce the feelings of depression due to the production of serotonin, which improves your mood. Protein-rich foods include milk, eggs, lean beef, yogurt, chicken, turkey, broccoli, fish, nuts, and oats. 

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The Bottom Line

By altering the types of bacteria in your gut, it may be possible to improve your brain health.