What is the gut microbiome?
A biome is a diverse ecosystem which primarily comprises the environment and its inhabitants. The gut inside our intestines is a miniature version of the biome which consists of trillions of microorganisms. These microscopic organisms mostly include a huge number of bacteria, along with viruses, fungi, and parasites.
Everyone has a unique microbiome and we develop the first gut microbiomes as infants through breastfeeding or vaginal delivery. However, in our later stages of life, with the exposure of diet and environment, the new microorganisms are introduced to our existing biome. Some of these exposures can damage as well as reduce the gut microbiome.
Why is the gut microbiome important for us?
The microorganisms in our gut tend to have a symbiotic relationship with the hosts, which is the human body in which these microorganisms live. This kind of relationship benefits both the host as well as the microorganisms. We provide them with food, and shelter, and in return they provide us with essential fermentation of non-digestible foods such as dietary fibers and endogenous intestinal mucus. With the help of this fermentation process, there is growth of special microbes which produce short chain fatty acids (SCFAs) and gasses. The primary SCFA’s that get synthesized are acetate, propionate and butyrate.
Butyrate is the main source of energy for the cells lining our colon, also known as colonocytes. This energy source helps the colonocytes in proper functioning. Butyrate additionally helps in maintaining oxygen balance. It helps the colon cells to burn oxygen, which eventually creates a low-oxygen environment in the gut. This low-oxygen level is highly important in keeping the gut bacteria balanced and healthy, preventing dysbiosis or simply harmful imbalance. Butyrate further helps in controlling the blood sugar levels and energy balance by activating certain processes in the gut. Lastly, butyrate is extremely effective to trigger the death of cancer cells in the colon.
The other two SCFA’s that are produced in the gut are propionate and acetate, and play different roles in the body. Propionate is sent to the liver, where it plays an important role in regulating blood sugar production and it also sends signals to the brain that will monitor the satiety feelings or the feeling of fullness. Acetate plays a very crucial role in monitoring the growth of other gut bacteria by traveling to different parts of the body and it is actively involved in the processes like cholesterol metabolism as well as in fat production (lipogenesis). It also helps in regulating appetite by sending signals to the brain.
Studies done on mice show that more SCFA’s in the gut helps people in maintaining the weight without gaining the excess weight. This also helps in having better insulin sensitivity, which reduces the risk of diabetes. Specifically, butyrate and propionate seem to control gut hormones and simultaneously reduce appetite and food intake. However, acetate doesn’t have the similar effect. Hence, it becomes very important to consult an expert gut health nutritionist to manage the food in such a way that the gut bacteria are promoted which will eventually help in maintaining weight.
In addition to this, the enzymes from the gut microbes help in breaking down the bile acids, which play a vital role in digesting fats. These break down bile acids and act as a signal in the body, eventually affecting various pathways that regulate metabolism and other functions.
What does your gut microbiome do?
The gut microbiome interacts with almost all of your body systems and it further assists with various body functions. Many healthcare providers have described gut microbiome as being almost like an organ due to its active role in the body. There are a lot of interactions which have been explored while there are many which are still unknown. The gut microbiome tends to interact with a lot of body systems and assists in various body functions. The gut nutrition hence, becomes of utmost importance. The following is the list of body systems which require gut microbiome for their smooth functions:
1. Digestive System
There are certain complex carbohydrates and dietary fibers which are unable to break down on their own. Hence, the bacteria in the gut helps them in breaking down. They produce short chain fatty acids (SCFA’s) as byproducts, which are important nutrients. They are also responsible for providing enzymes necessary to synthesize certain vitamins, which include B1, B9, B12 and K.
The above-mentioned nutrients might seem as micronutrients but their deficiencies can have a big impact on our health. Particularly the SCFA’s feed in the cells in your gut lining and help to keep the overall gut environment healthy.
Gut bacteria also help in metabolizing the bile in the intestine. The liver is responsible for sending bile to the small intestine to facilitate the fat digestion. When the digestion is over, the gut bacteria and the enzymes made by them help to break it down so that the bile acids can be reabsorbed and recycled by the liver. This entire process is known as Enterohepatic Circulation.
If this above-mentioned process stops, our body will be unable to recycle the bile acids and our liver will not have enough to produce new bile. Our digestive system wouldn’t get the bile it actually needs to digest and to absorb fat. one of the components of bile, leftover cholesterol, would eventually build up in your blood.
2. Immune System:
There are many beneficial microbes in our gut which help to train our immune system to tell them apart from the unhelpful, pathogenic types. Our gut is our largest immune organ, which comprises up to 70-80% of our body’s immunity cells. These cells help to clear out the several pathogens that pass through it on a daily basis.
The helpful gut microbes compete directly with disadvantageous types of nutrients, preventing them from taking up too much of the territory. Certain chronic bacterial infections like H. pylori or C. difficile are directly linked to the reduced gut microorganisms.
The byproducts of the beneficial gut bacteria, short-chain fatty acids (SCFA’s), have a crucial role to play in your immune system. They work in maintaining our gut barrier, keeping the bacterial and the bacterial toxins inside from escaping into our bloodstream. They also portray anti-inflammatory properties in our gut.
Short-chain fatty acids appear to suppress the inflammatory reactions as inflammation is a key function of our immune system. Chronic or severe inflammation is a feature of any autoimmune disease and this may have a role in several other disease conditions, which also includes diseases like cancer.
3. Nervous System:
The gut-brain axis is a network of nerves, neurons and neurotransmitters that pass through our GI tract. The gut microbes can affect our nervous system through this gut-brain axis. There are some bacteria which produce or stimulate the production of neurotransmitters like serotonin that send the chemical signals to our brain.
Bacterial end products can also affect our nervous system. SCFA’s appear to have positive effects, while bacterial toxins may damage the nerves lead harmful effects. There are many researches which investigate that gut microbiomes may be linked to numerous neurological, behavioural, nerve pain and mood swings.
4. Endocrine System:
The endocrine cells in our gut lining interact with the gut microbiomes and their products. These enteroendocrine cells make our gut the largest endocrine system organ in our body. The aspects of our metabolism, which includes blood sugar, hunger and satiety are regulated by the hormones secreted by these microbes.
There are ongoing researches which keep exploring how our microbes would be involved in metabolic syndrome (obesity, insulin resistance, and type 2 diabetes) and excess fat storage in our liver. However, it is yet to be clear.
Where are your gut bacteria?
Our gut is majorly the gastrointestinal tract (GI) or sometimes it’s also used for your intestine. There is presence of some gut microbiota in our stomach and in our small intestine but it is majorly in the large intestine (colon). These float inside and tend to attach themselves to the mucous lining of the inner walls (mucosa).
There are different types of gut bacteria living in the colon and a different set is present in the other parts. They are majorly anaerobic bacteria that require a low-oxygen environment to survive. The high oxygen levels, fast movements and strong digestive juices in the upper GI tract unable these bacteria to colonize there.
Anaerobic gut bacteria perform important functions within the colon that can be performed only by them. They help in breaking down the indigestible fibers in our GI tract and synthesize important nutrients that we cannot get otherwise.
If these bacteria stray beyond our colon, they can be harmful. Colon bacteria that manage to creep up to our small intestine and settles there can interfere with the digestive processes there. Colon bacteria that invade our colon wall, or that escapes through a wound in our colon we; can lead to infections in the body.
Conditions and Disorders:
What is dysbiosis?
There are several healthcare providers who use the terminology “dysbiosis” that refers to an unbalanced or unhealthy gut microbiome.
Dysbiosis typically means:
- A loss or deficit of beneficial bacteria.
- Overgrowth of possible pathogenic or bad bacteria.
- Loss of overall bacterial diversity.
The process of dysbiosis can start with one of the above-mentioned factors, but the others tend to follow. A drop in the beneficial bacterial leaves the gut more vulnerable to more disease-causing or invasive types. These types can overrun the other microbes living there, resulting in reduction of the overall diversity in our microbiome.
What environmental factors affect your gut microbiome?
The gut microbiome is affected by the nutrients, pollutants, pests and weeds, just like any other garden. The different seasons or life cycles and the diversity of the plants also affect the gut microbiome. In your gut, this would imply to your diet, chemical exposure, disease-causing organisms and regular bowel movements.
1. Diet:
A variety of plant fibers is required to thrive a variety of microorganisms in our gut microbiome. Different whole foods are required by different organisms. In turn, they synthesize short-chain fatty acids and the other end products that will help nourish our gut and eventually lower the pH inside, which Favors the growth of more beneficial microbes.
On the flip side, a diet which is high in sugar and saturated fats tend to Favor the growth of less beneficial types of microbes. The foods that can be harmful for the gut microbiome includes primarily the processed foods that not just lacks fiber but also has low micronutrients (vitamins and minerals)
2. Chemicals:
Environmental toxins like alcohol, tobacco, smoke and pollutants are the chemicals that may poison our gut microbiome. Furthermore, pesticides which include antibiotics also tend to sweep away the good bacteria along with the bad bacteria. The other medications, like the acid blockers, also affect the microbiome by changing the pH inside.
The temporary chemical exposure, like a brief prescription for a medication while one is unwell, leads to a short-term damage to the microbiome which usually leads to a quick recovery. But chronic exposure can affect the composition of the gut microbiome. A person who includes prolonged medication or uses substances like alcohol frequently, can prevent certain microorganisms from thriving.
3. Diversity:
Different types of microorganisms support each other in a healthy gut microbiome. It is the same as how different plants in a garden cross-pollinate or nourish the soil for each other. For instance, some types feed the other types by breaking down the compound, or their end products change the pH of the soil.
On the contrary, a microbiome that is unable to support a healthy variety of microorganisms is much more vulnerable to being overrun by the invasive types. Without such healthy competition, these weeds and pests take over the habitat and deplete the resources that the other types need to survive.
4. Motility:
Motility refers to the regular movement of our bowels. This is how the crop of microorganisms turns over. There are many that come out of your poop, after traveling through our colon, where they tend to help break down undigested compounds into nutrients that can be absorbed by our body.
The distribution of the different microbes into different places is decided by the movement of food and waste through our GI tract. If it’s too fast, they don’t have time to settle or to do their jobs before clearing out. But if it’s too slow, they can overeat and overgrow, spreading beyond their territory.
What health conditions and disorders relate to our gut microbiome?
Conditions that can directly relate to gut dysbiosis are as follows:
- Infections – Certain invasive pathogens may cause temporary or chronic infections in our gut. These infections can lead to diarrhea, inflammation, and toxic damage to the gut lining. Some infections directly invade the gut barrier, threatening to escape into a bloodstream and go systemic. Dysbiosis weakens our gut’s defense against these pathogens.
- Inflammatory bowel disease (IBD) – it is a collection of autoimmune conditions in your gut that includes ulcerative colitis, microscopic colitis, and Crohn’s disease. One of the criteria for diagnosing IBD is gut dysbiosis.
- SIBO (Small intestinal bacterial overgrowth) – This is the dysbiosis of your small intestine and it means that the certain types of bacteria in the intestine may have overgrown, by using too many resources or by synthesizing too many byproducts. In certain cases, the bacteria from the large intestine tend to migrate or move in the small intestine and would settle there. This is not the place where they belong. Hence, it results in slow gut motility.
- Atherosclerosis – there are certain less desirable gut microorganisms which contribute to our cardiovascular risk by synthesizing a byproduct known as trimethylamine N-oxide (TMOA). This byproduct builds up in the arteries, contributing to atherosclerosis i.e. hardening of the arteries. It is one of the substances that is checked in the cardiac blood tests for determining the risk of coronary heart disease (CAD).
Some of the other conditions that could be indirectly linked to a gut dysbiosis include:
- Allergies
- Anxiety
- Asthma
- Autism
- Chronic fatigue syndrome (CFS)
- Colon cancer
- Diabetes
- Depression
- Fatty liver disease
- Irritable bowel syndrome (IBS)
- Liver cancer
- Multiple sclerosis (MS)
- Neurodegenerative diseases
- Obesity
- Pancreatic cancer
- Rheumatoid arthritis (RA)
What are common signs or symptoms of a problem with my gut microbiome?
Typical symptoms of gut dysbiosis include:
- Gas and gas pain.
- Bloated stomach.
- Poor digestion.
- Lower abdominal pain.
- Diarrhea.
- Constipation.
Can I take a test to check the health of my gut microbiome?
There are many commercial labs that would offer microbiome testing for consumers. Your stool, blood and a breath test are done to measure the different gasses in your breath that are the byproducts of certain bacteria in your gut. The reports will let you know about the composition of our gut microbiome. However, the clinical healthcare providers would generally not recommend these tests because we still do not know much about the different types of gut microbes or how they would affect their health.
It is best to consult a gut health nutritionist and get a customized diet plan that would focus on the healing of the dysbiosis. The diet and lifestyle changes play a major role in the healing of the gut health and improving the gut microbiome.