Gut-Brain Connection: A century ago, a few isolated studies found a link between diet and mental health. Now, it’s emerging that the bacteria inside us could be a crucial link between the food we eat and how we feel.
If you’ve ever “gone with your gut” to make a decision or felt “butterflies in your stomach” when nervous, you’re likely getting signals from an unexpected source: your second brain. Hidden in the walls of the digestive system, this “brain in your gut” is revolutionizing medicine’s understanding of the links between digestion, mood, health and even the way you think.
Scientists call this little brain the enteric nervous system (ENS). And it’s not so little. The ENS is two thin layers of more than 100 million nerve cells lining your gastrointestinal tract from esophagus to rectum.
Unlike the big brain in your skull, the ENS can’t balance your checkbook or compose a love note. Its main role is controlling digestion, from swallowing to the release of enzymes that break down food to the control of blood flow that helps with nutrient absorption to elimination. The enteric nervous system doesn’t seem capable of thought as we know it, but it communicates back and forth with our big brain—with profound results.
The ENS may trigger big emotional shifts experienced by people coping with irritable bowel syndrome (IBS) and functional bowel problems such as constipation, diarrhea, bloating, pain and stomach upset. For decades, researchers and doctors thought that anxiety and depression contributed to these problems. But our studies and others show that it may also be the other way around. Researchers are finding evidence that irritation in the gastrointestinal system may send signals to the central nervous system (CNS) that trigger mood changes.
These new findings may explain why a higher-than-normal percentage of people with IBS and functional bowel problems develop depression and anxiety. That’s important, because up to 30-40% of the population has functional bowel problems at some point.
This new understanding of the ENS-CNS connection helps explain the effectiveness of IBS and bowel-disorder treatments such as mind-body therapies like cognitive behavioral therapy (CBT) and hypnotherapy. Our two brains "talk" to each other, so therapies that help one may help the other. Psychological interventions such as hypnotherapy may also help to “improve communications” between the big brain and the brain in our gut.
In turn, creating an optimal gut biome (collection of bacteria) makes the second brain happy. If the brain in our gut is happy, so is the big brain in our head!
An estimated 90% of the body's serotonin is produced in the gut, where it influences gut immunity as well as our mood.
Your microbiome—the diverse population of microbes (bacteria) that live in your gastrointestinal (GI) tract—plays an important role in the health of your gut, and in other aspects of your physical health, from inflammatory skin disorders to obesity.
Researchers now say that this role of promoting good health may extend to include the health of your brain and neurological systems.
What’s the Connection? Gut-Brain Connection
The thousands of different types of both “good” and “bad” bacteria that populate the microbiome normally exist in a balance in favor of beneficial bacteria that help prevent overgrowth of bad bacteria that can harm your heath.
Studies have shown there is potential harm associated with an imbalance in the microbiome due to inflammation, intestinal permeability or lack of bacterial diversity, any of which may be associated with an overgrowth of unhealthy bacteria. In some cases, researchers are confronted with the classic “chicken or egg” question with respect to the association between gut bacteria and poor health, in terms of which comes first. Does an overgrowth cause the disorder or does the disorder cause an overgrowth of bad bacteria?
Bacteria on the Brain Gut-Brain Connection
Current thinking in the field of neuropsychology and the study of mental health problems includes strong speculation that bipolar disorder, schizophrenia, and other psychological or neurological problems may also be associated with alternations in the microbiome. Researchers speculate that any disruption to the normal, healthful balance of bacteria in the microbiome can cause the immune system to overreact and contribute to inflammation of the GI tract, in turn leading to the development of symptoms of disease that occur not only throughout your body, but also in your brain.
This system of connections and communication between the gastrointestinal tract and the brain is referred to as the “gut-brain axis.” Some researchers speculate that infections occurring in early life could negatively affect the mucosal membrane in the GI tract, disrupting the gut-brain axis, and interfering with normal brain development. The mucosal membrane can also be altered in other ways, such as through poor diet choices, radiation treatment, antibiotic use, and chemotherapy.
What You Can Do Gut-Brain Connection
To maintain or restore the health of your microbiome and support good overall health, it is important to maintain a strong balance in favor of beneficial bacteria in your digestive tract. The first step is to eat a well-balanced diet that includes foods with probiotic or prebiotic ingredients that support microbial health by helping to restore balance to the gut microbiome. These are foods that contain live beneficial (probiotic) bacteria and, in the case of prebiotics, contain substances like specific types of fiber that nurture the growth of probiotic bacteria.
Probiotic Foods Gut-Brain Connection
Until more is known, look to a variety of readily available probiotic foods that supply varying amounts beneficial live bacteria that grow during carefully controlled fermentation processes. Some of these are common foods you may already be including in diet, while others may seem a bit more exotic, though they are readily available in supermarkets. Probiotic foods and beverages include plain yogurt, kefir, cottage cheese, fresh sauerkraut, kimchi, kombucha, apple cider vinegar, and miso. Keep in mind that the probiotic effects of these foods are destroyed by cooking, processing, or preserving at high temperatures.
Unlike probiotic foods, prebiotic foods do not contain living organisms. They contribute to the health of the microbiome because they contain indigestible fibers that ferment in the GI tract, where they are consumed by probiotic bacteria and converted into other healthful substances. Prebiotic foods include artichokes, leeks, onions, garlic, chicory, cabbage, asparagus, legumes, and oats.
While probiotic supplements have been shown to improve symptoms of depression, anxiety, obsessive-compulsive disorder and other psychological and neurological conditions, their use should be discussed with a physician or mental health care provider. If you're ready to restore the balance in your microbiome and feel better physically and emotionally, I encourage you to consider Life Extension as your go-to sources for supplements>>>
The majority of studies looking at the gut-brain axis and the use of probiotics to reduce symptoms and occurrence of mental health disorders such as bipolar and schizophrenia are preliminary, preclinical studies that support the theory but have yet to demonstrate an absolute effect in humans with mental health issues. Although early research points to positive outcomes, larger population, and human clinical studies are necessary to determine which patients can truly benefit from probiotic or “psychobiotic” treatment of mental health disorders, and how these treatments can best be applied.
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