Functional Neurology: What is the Gut-Brain Axis?

How often do you get irritable, shaky, or have light-headedness between meals? How often do you have difficulty concentrating before eating? How often do you feel agitated, easily upset, and nervous between meals? Many researchers and healthcare professionals believe that your brain and gut are connected. Moreover, recent research studies have demonstrated that the brain can affect gut health and the gut can affect brain health. The communication system between your brain and gut is known as the gut-brain axis. In the following article, we will discuss the gut-brain axis. 

Understanding the Gut-Brain Axis

The gut-brain axis is the communication network that connects your gut and brain. These two fundamental organs are both physically and biochemically connected in a variety of different ways. The neurons and the vagus nerve are essential for the brain and central nervous system (CNS). There are approximately 100 billion neurons in the human brain. The gut itself also contains about 500 million neurons, all of which are connected to the brain through nerves found in the nervous system. The vagus nerve is one of the largest nerves connecting the gut and brain. It sends signals in both directions. 

By way of instance, in several animal research studies, stress can ultimately affect the signals sent through the vagus nerve and it can also cause gastrointestinal health issues. Another research study conducted on humans found that people with irritable bowel syndrome (IBS) or Crohn’s disease had decreased vagal tone which suggests the decreased function of the vagus nerve. One research study in mice found that feeding them a probiotic reduced the amount of stress hormone in their blood. According to the research study, however, when the vagus nerve was cut, the probiotic had no effect. 

The brain and gut are also ultimately connected through chemicals known as neurotransmitters. Neurotransmitters created in the brain help regulate mood, including feelings and emotions. Furthermore, the neurotransmitter known as serotonin can help manage happiness and it also helps control the circadian rhythm or the human body's internal clock. Surprisingly, many of these neurotransmitters are also created by the cells and the trillions of microbes living in the gut. A large amount of serotonin is developed in the gut. Gut microbes also produce a neurotransmitter known as gamma-aminobutyric acid (GABA) which helps regulate feelings of fear and anxiety. Research studies in mice found that probiotics increase GABA and decrease anxiety and depression. 

Brain, Gut Microbes, and Other Chemicals

The trillions of microbes that live in your gut can also make a variety of other different chemicals that may ultimately affect your brain function. Gut microbes create many short-chain fatty acids (SCFA), including butyrate, propionate, and acetate. Furthermore, these can ultimately make SCFA by digesting fiber. SCFA can also affect overall brain function in a variety of different ways, such as by reducing appetite. One research study found that consuming propionate can help reduce food intake and reduce activity in the brain associated with the reward of high-energy food. Butyrate, another SCFA, and the microbes that develop it are also fundamental for producing the protective shield between the brain and the blood, known as the blood-brain barrier. 

Gut microbes can also help metabolize bile acids and amino acids to create a variety of other different chemicals that affect brain function. Bile acids are chemicals produced by the liver which is generally associated with the absorption of dietary fats. However, these may also ultimately affect the brain. Two research studies in mice found that stress and several health issues decreased the production of bile acids by gut bacteria and these can also change the genes involved in their production. According to researchers and healthcare professionals, the gut-brain axis may also be affected by chronic inflammation. 

Gut-Brain Axis and Inflammation

According to several research studies, the gut-brain axis is also connected to the immune system. Evidence found in clinical trials demonstrated that the gut and gut microbes play an essential role in the immune system and inflammation by regulating and managing what passes through the human body as well as what is excreted from the human body. If the immune system continues to stay activated for an extended period of time, it can lead to inflammation, which is associated with a variety of different brain health issues, including depression and Alzheimer’s disease. Lipopolysaccharide (LPS) is an inflammatory toxin created by several types of bacteria. It can ultimately cause inflammation if too much of it passes from the gut into the blood. This can happen when the gut becomes leaky, which allows bacteria and LPS to enter into the blood. Inflammation and high LPS have been associated with brain health issues, such as severe depression, dementia, and schizophrenia. Leaky gut can affect the blood-brain barrier and change the gut-brain axis. 

Gut bacteria can ultimately affect overall brain health and wellness, therefore, changing your gut bacteria may improve brain well-being. Probiotics are live bacteria that provide many health benefits. However, not all probiotics are the same. Probiotics that affect the brain are generally known as “psychobiotics”. Several probiotics have been demonstrated to help improve symptoms of stress, anxiety, and depression. One small research study conducted on 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 considerably helped improve their symptoms. Prebiotics, or fibers fermented by gut bacteria, may also affect brain health. One research study found that taking a prebiotic called galactooligosaccharides for three weeks considerably reduced stress hormones in the human body, known as cortisol. 

Brain health issues and neurological diseases can happen due to a variety of factors. However, recent research studies have shown that leaky gut can ultimately affect overall brain health and wellness. The gut-brain axis is the physical and chemical connection between the gut and brain. Millions of neurons are found throughout the brain and gut where the neurotransmitters and other chemicals created in the gut can also affect the brain. However, by altering the types of bacteria in the gut, it may be possible to improve overall brain health and wellness. A naturopathic doctor or chiropractor can help assess the source of a patient's symptoms and determine the best course of treatment for the health issue or medical condition. - Dr. Alex Jimenez D.C., C.C.S.T. Insight

How often do you get irritable, shaky, or have light-headedness between meals? How often do you have difficulty concentrating before eating? How often do you feel agitated, easily upset, and nervous between meals? Many researchers and healthcare professionals believe that your brain and gut are connected. Moreover, recent research studies have demonstrated that the brain can affect gut health and the gut can affect brain health. The communication system between your brain and gut is known as the gut-brain axis. In the article above, we discussed the gut-brain axis. 

The scope of our information is limited to chiropractic, musculoskeletal, and nervous health issues or functional medicine articles, topics, and discussions. We use functional health protocols to treat injuries or disorders of the musculoskeletal system. Our office has made a reasonable attempt to provide supportive citations and has identified the relevant research study or studies supporting our posts. We also make copies of supporting research studies available to the board and or the public upon request. To further discuss the subject matter above, please feel free to ask Dr. Alex Jimenez or contact us at 915-850-0900. 

Curated by Dr. Alex Jimenez 

References:

• Robertson, Ruairi. “The Gut-Brain Connection: How It Works and the Role of Nutrition.” Healthline, 27 June 2018, www.healthline.com/nutrition/gut-brain-connection.