The Gut Microbiome Explained

Did you know you have a unique ecosystem of trillions of organisms living in your digestive tract that are essential to your health and wellbeing? These include bacteria, fungi and viruses.

https://www.youtube.com/watch?v=_EfnP2XoKe0

The gut microbiome plays a role in the physiological following processes:

1. Digestion and Absorption: the bacteria in your gut assist in breaking down complex carbohydrates and dietary fibers and in turn, produce short-chain fatty acids such as butyrate. They also are involved in the synthesis and absorption of certain vitamins and minerals such as B1, B2, B3, B5, B6, Biotin, B12, Folate and Vitamin K. Gut microbes also influence the uptake of many minerals such as iodine, selenium, zinc and iron. They also play a role in fat absorption, because their enzymes help break down bile acids in a process called enterohepatic circulation. When this isn’t working properly, you can have problems with excess cholesterol and impaired fat absorption.

2. Brain Function and Neurotransmitter Production: have you ever heard of the gut-brain axis? There is a neurological connection between your gut and brain and believe it or not, many of your microbes are involved in the production of neurotransmitters such as serotonin (90% is made in your gut). Recent research has been investigating the connection between gut dysbiosis and mood disorders such as anxiety, depression, bipolar disorders, eating disorders, PTSD and more. There is also evidence of decreased gut microbiome diversity in individuals with autism spectrum disorders. (check out some papers here, here and here). 

3. Hormone Regulation: certain gut microbes produce hormones from steroids in bile that impact reproductive hormones and also modulate estrogen and testosterone through secreting an enzyme called  β-glucuronidase. Gut bacteria also impact hypothalamic signaling pathways that control things like FSH, LH, TRH output and these metabolites have a direct impact on endocrine function (read more here). In fact many hormone imbalances and disorders such as endometriosis have been linked to intestinal dysbiosis. There is also an important relationship between your gut microbes and thyroid function, referred to as the thyroid-gut axis (check out an in depth paper here). 

4. Metabolism, Energy Production and Weight Regulation: The bacteria in your gut determine caloric extraction from food and control how the food you eat is utilized and stored. The gut microbiome also interacts with cells that produce hunger and satiety hormones. These microbes also impact your insulin sensitivity and sugar (glucose) regulation. The gut microbiome is also sometimes called the “second liver” due to its important role in detoxification. Microbes also play a role in fat absorption, because their enzymes help break down bile acids in a process called enterohepatic circulation. When this isn’t working properly, you can have problems with excess cholesterol and impaired fat absorption. This means a gut imbalance can lead to things such as obesity, insulin resistance/diabetes, NAFLD, and metabolic syndrome. (check out some studies here, here and here). 

5. Immunity: the microbes in your gut help prime your immune cells in recognizing harmful pathogenic invaders. In fact, 80% of your immune cells are located in your gut. Gut microbes help protect against pathogenic bacteria, viruses and parasites. The short-chain fatty acids produced by your gut bacteria also help regulate inflammation and maintain your gut barrier. 

6. Inflammatory Cascades: gut microbes play a powerful role in regulating inflammation. Inflammation is a normal bodily response, but if it doesn’t rectify as it should, it can turn into a chronic inflammatory process that worsens/causes other issues. This means if your gut microbiome is not balanced, you could end up with chronic inflammation contributing to increased pain, arthritis, heart disease, migraines, brain fog, sleep disturbances, memory issues and more. An unbalanced gut microbiome or undiagnosed gut infection can also lead to the development of many inflammatory bowel diseases as a result. (check out some studies here, here and here)

7. Bone Health: the gut microbiome regulates bone homeostasis through immune signaling, hormone pathways (estrogen, serotonin, PTH, IGF-I), SCFA production and nutrient digestion and absorption. Read more on how the gut microbiome influences bone health here and here.