Understanding Gut Hormones: The Key to Digestive Health
The human gut is a fascinating and complex ecosystem that plays a crucial role in our health and well-being. The gut’s primary function is to digest food and absorb nutrients. The gut is also home to trillions of bacteria, fungi, and other microbes that form the gut microbiome.
Recent research has shed light on the importance of gut health and its connection to various aspects of our physical and mental health. In particular, gut hormones have emerged as key players in regulating digestion, metabolism, and even mood. See how the gut microbiota and gut hormones affect each other and your health.
Table of Contents
The Gut Microbiome: A Balancing Act
Trillions of bacteria, fungi, and other microbes (the microbiota) make up the gut microbiome. It is a remarkable ecosystem that lives in our gastrointestinal tract. It not only aids in digesting and absorbing nutrients but also plays a vital role in our immune system, physical health, and mental well-being.
Bacteria and other microorganisms are transferred to you from your mother at birth. Your microbiome evolves throughout your lifetime in response to:
- Your diet
- Environmental factors
- Mode of birth
- Genetic factors
- Antibiotic use
Each person harbors a unique collection of bacteria that can have a significant effect on their physical and mental health.
Gut dysbiosis occurs when there is an imbalance between the beneficial and harmful bacteria in the gut microbiome. This imbalance can arise from various factors, such as:
- Poor dietary choices
- Use of medications like antibiotics and birth control
- Alcohol consumption.
Gut dysbiosis often causes gastrointestinal symptoms such as an upset stomach, bloating, gas, constipation, or diarrhea. However, the effects of gut dysbiosis extend beyond digestive discomfort, as it can also disrupt hormonal balance. Your brain, body, hormone levels, and gut microbiome are all linked. A change in your gut microbiome affects your health, and your health affects your microbiome.
The Gut Hormones
Gastrointestinal hormone-producing cells can secrete their product into the bloodstream (endocrine), the lumen of the gut (exocrine), or locally, without entering the bloodstream (paracrine).
These five hormones qualify as endocrine gastrointestinal hormones:1
- Gastrin: stimulates acid secretion in the stomach and inhibits the release of secretin and GIP.
- Cholecystokinin (CCK): slows stomach emptying and stimulates the release of bile and digestive enzymes.
- Secretin: inhibits gastrin and acid secretion in the stomach and neutralizes acidity in the small intestine.
- Glucose-dependent insulinotropic hormone (GIP): stimulates insulin release, induces satiety, breaks down fat, and slows stomach emptying.
- Motilin: increases waves of contraction through the gut.
These hormones act locally as paracrine hormones.
- Somatostatin: inhibits the release of other gastric hormones.
- Histamine: stimulates acid release.
These hormones qualify as both endocrine and paracrine hormones:1,6
- Glucagon-like peptide-1 (GLP-1): slows stomach emptying, induces satiety, and increases insulin sensitivity. It curbs your appetite by acting in the brain at the hypothalamus or via the gut-brain axis.
- Pancreatic polypeptide: regulates pancreatic secretion.
- Peptide YY: helps induce satiety.
The Gut-Brain Axis
The gut-brain axis is a bidirectional communication system between the brain and the gastrointestinal tract. Recent research has shown that the composition of the gut microbiome and its relationship with gut hormones can have significant effects on physical and mental health.
The microbiota affects brain function by secreting molecules that function like neurotransmitters (brain chemicals). Some bacteria can produce these common brain chemicals: GABA, histamine, acetylcholine, dopamine, tryptophan decarboxylase, or tryptamine.4
Changes in the microbiome and the chemicals they release are thought to contribute to brain disorders. Neurodegenerative diseases, epilepsy, autism, and Parkinson’s disease are all linked to changes in the microbiota.2
When germ-free mice are fed fecal samples from mice with depressive or other neurologic behaviors, the recipient mice begin showing these same symptoms.2
Germ-free mice (without a microbiota) experience significant changes in brain function and behaviors when compared to mice with a healthy and diverse microbiota. Studying these mice makes it possible for researchers to understand the effect of your microbiome on you.
The Gut Microbiome and Gut Hormones
Metabolites produced by gut bacteria, such as short-chain fatty acids (SCFAs), can influence the release of gut hormones. For example, SCFAs can stimulate the release of PYY and GLP-1, which contribute to feelings of fullness and satiety.
Some gut bacteria can affect ghrelin secretion. Ghrelin is a hormone that increases appetite and hunger.
The genus Bacteroides is associated with increased carbohydrate and fat intake, as well as an increased long-term consumption of dietary protein and animal fat. Conversely, the genus Prevotella is associated with increased long-term carbohydrate intake.4 Your dietary choices help shape your microbiome.
Gut bacteria can cause food cravings to ensure you eat the nutrients that support their growth or inhibit the growth of their competitors.3
Manipulating the microbiome can potentially treat diseases such as obesity. The gut microbiome can be modulated in the following ways:4
- When taking probiotics with live beneficial bacterial strains, continuous consumption is typically necessary
- Taking prebiotics high in host-indigestible dietary fiber
- Taking antibiotics targeted toward certain gut bacteria
- Transplanting fecal microbiota from person to person
The Estrobolome: A Link Between Gut Health and Hormonal Balance
The gut microbiome can influence hormonal balance. One example of this interaction is estrogen balance.
Estrogen is a hormone primarily metabolized in the liver and secreted in bile. Gut bacteria process estrogen.
The gut microbiome contains a collection of bacteria known as the estrobolome. These bacteria are responsible for metabolizing and modulating the body’s estrogen levels.
These microbes synthesize an enzyme called beta-glucuronidase. This enzyme breaks down complex carbohydrates, reabsorbs micronutrients, and converts inactive estrogen into an active form for use by the body.
A disruption in the estrobolome can lead to hormonal imbalances. It can cause too high or too low estrogen levels.
Disruptions in the microbiome and estrogen levels can increase your risk of the following conditions:5
- Polycystic ovary syndrome
- Endometrial hyperplasia
- Metabolic syndrome
- Disruptions in brain function
How Do You Fix Hormonal Gut Problems?
Maintaining a healthy gut is extremely important for achieving hormonal balance and reaping the benefits it entails.
Hormones exert effects on your mental, physical, and emotional health.
Try these strategies to increase the diversity of your microbiome and decrease inflammation.
Chronic stress can lead to overproduction of cortisol and catecholamines such as epinephrine and norepinephrine.
These hormones regulate how quickly waves of contractions are transmitted through your gut, how well nutrients are absorbed and metabolized from your food, the effectiveness of your innate immune system, and the diversity of your microbiome. Chronic stress can cause marked changes in the microbiome, which can impact your health.6,7
Indigestion, bloating, and abdominal discomfort are just some of the gastrointestinal effects of chronic stress. Other potential side effects of chronic stress include:
- Changes in gut motility can lead to constipation or diarrhea.
- A leaky gut can trigger inflammation.
- Disruption in your gut microbiome.
- Food cravings and changes in appetite that are not due to hunger.
Prioritize physical activity throughout the day. Try to get 30 minutes of moderate-intensity exercise most days of the week. This can help reduce your perception of stress, support your immune function, and improve your gut health.
Research suggests that regular exercise can improve your microbiome’s diversity, improve your glucose tolerance, and improve your mood and energy levels.
When participants in one study stopped exercising for two weeks, they experienced increased fatigue and a poor mood. This may be related to how the gut microbiota controls tryptophan metabolism.6
Consume a Gut-Healthy Diet
The microbiome of people who consume a Western diet rich in sugar, salt, and fat is similar to the microbiome found in people with obesity. The Western diet is a major contributor to metabolic conditions such as type 2 diabetes, obesity, and poor gut health.
Prebiotics are any substrate that host microorganisms use to confer a health benefit. Consume a diet high in dietary fiber. Good sources of dietary fiber include fruits and vegetables such as asparagus, leek, banana, and chicory, and grains such as oats and wheat. Regular consumption of prebiotics can change the proportions of microbes in the gut, which can affect physical and mental health.6
A Western diet and dysbiosis increase your risk for metabolic disorders and obesity. In addition to making beneficial lifestyle changes, many people find that GLP-1 receptor agonists, like semaglutide, can treat obesity. GLP-1 is a gut hormone that slows stomach emptying, increases satiety and reduces appetite.
If you are concerned about your body weight, talk with a treatment specialist at Invigor Medical to learn more about weight loss medications and whether you are a candidate for taking them.
- Alcock J, Maley CC, Aktipis CA. Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms. Bioessays. 2014 Oct;36(10):940-9. doi: 10.1002/bies.201400071. Epub 2014 Aug 8. PMID: 25103109; PMCID: PMC4270213.
- van de Wouw, M., Schellekens, H., Dinan, T. G., & Cryan, J. F. (2017). Microbiota-gut-brain axis: Modulator of host metabolism and appetite. The Journal of Nutrition, 147(5), 727–745. https://doi.org/10.3945/jn.116.240481
- Baker JM, Al-Nakkash L, Herbst-Kralovetz MM. Estrogen-gut microbiome axis: Physiological and clinical implications. Maturitas. 2017 Sep;103:45-53. doi: 10.1016/j.maturitas.2017.06.025. Epub 2017 Jun 23. PMID: 28778332.
- Cryan JF, O’Riordan KJ, Cowan CSM, et al. The microbiota-gut-brain axis. Physiol Rev. 2019;99(4):1877-2013. doi:10.1152/physrev.00018.2018
- Karl JP, Hatch AM, Arcidiacono SM, et al. Effects of psychological, environmental and physical stressors on the gut microbiota. Front Microbiol. 2018;9:2013. doi:10.3389/fmicb.2018.02013