Your body is full of trillions of bacteria, viruses and fungi. They are collectively known as the microbiome. While some bacteria are associated with disease, others are actually extremely important for your immune system, heart, weight and many other aspects of health.
What Is the Gut Microbiome?
Bacteria, viruses, fungi and other microscopic living things are referred to as microorganisms, or microbes, for short. Trillions of these microbes exist mainly inside your intestines and on your skin. Most of the microbes in your intestines are found in a “pocket” of your large intestine, and they are referred to as the gut microbiome.
There are more bacterial cells in your body than human cells. There are roughly 40 trillion bacterial cells in your body and only 30 trillion human cells. That means you are more bacteria than human. What’s more, there are up to 1,000 species of bacteria in the human gut microbiome, and each of them plays a different role in your body. Most of them are extremely important for your health, while others may cause disease.
Altogether, these microbes may weigh as much as 2–5 pounds (1–2 kg), which is roughly the weight of your brain. Together, they function as an extra organ in your body and play a huge role in your health.
How Does It Affect Your Body?
Microbes play very important roles in the human body. In fact, without the gut microbiome, it would be very difficult to survive. The gut microbiome begins to affect your body the moment you are born. However, as you grow, your gut microbiome begins to diversify, meaning it starts to contain many different types of microbial species. Higher microbiome diversity is considered good for your health. Interestingly, the food you eat affects the diversity of your gut bacteria.
As your microbiome grows, it affects your body in a number of ways, including:
Digesting breast milk: Some of the bacteria that first begin to grow inside babies’ intestines digest the healthy sugars in breast milk that are important for growth.
Digesting fibre: Certain bacteria digest fibre. Fibre is vital as it may help prevent weight gain, diabetes, heart disease and the risk of cancer.
Helping control your immune system: By communicating with immune cells, the gut microbiome can control how your body responds to infection.
Helping control brain health: New research suggests that the gut microbiome may also affect the central nervous system, which controls brain function.
The Gut Microbiome May Affect Your Weight
There are thousands of different types of bacteria in your intestines, most of which benefit your health. However, having too many unhealthy microbes can lead to disease.
An imbalance of healthy and unhealthy microbes is sometimes called gut dysbiosis, and it may contribute to weight gain. Several well-known studies have shown that the gut microbiome differed completely between identical twins, one of whom was obese and one of whom was healthy. This demonstrated that differences in the microbiome were not genetic but possibly environmental.
It Affects Gut Health
The microbiome can also affect gut health and may play a role in intestinal diseases like irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). The bloating, cramps and abdominal pain that people with IBS experience may be due to gut dysbiosis. This is because the microbes produce a lot of gas and other chemicals, which contribute to the symptoms of intestinal discomfort. Taking certain probiotics that contain Bifidobacteria and Lactobacilli can reduce symptoms of IBS.
The Gut Microbiome May Benefit Heart Health
Interestingly, the gut microbiome may even affect heart health. A recent study in 1,500 people found that the gut microbiome played an important role in promoting “good” HDL cholesterol and triglycerides. Furthermore, certain beneficial bacteria within the gut microbiome, particularly Lactobacilli, may help reduce cholesterol when taken as a probiotic.
It May Help Control Blood Sugar and Lower the Risk of Diabetes
The gut microbiome also may help control blood sugar, which could affect the risk of diabetes. One particular study found that even when people ate the exact same foods, their blood sugar could vary greatly. This may be due to the types of bacteria in their guts.
It May Affect Brain Health
The gut microbiome may even benefit brain health in a number of ways. First, certain species of bacteria can help produce chemicals in the brain called neurotransmitters. For example, serotonin is an antidepressant neurotransmitter that’s mostly made in the gut. Second, the gut is physically connected to the brain through millions of nerves. Therefore, the gut microbiome may also affect brain health by helping control the messages that are sent to the brain through these nerves.
A number of studies have shown that people with various psychological disorders have different species of bacteria in their guts, compared to healthy people. This suggests that the gut microbiome may affect brain health. However, it’s unclear if this is simply due to different dietary and lifestyle habits. A small number of studies have also shown that certain probiotics can improve symptoms of depression and other mental health disorders.
How Can You Improve Your Gut Microbiome?
There are many ways to improve your gut microbiome, including:
Eat a diverse range of foods: This can lead to a diverse microbiome, which is an indicator of good gut health. In particular, legumes, beans and a measured amount of fruit (when considering those with diabetes) contain lots of fibre and can promote the growth of healthy Bifidobacteria.
Eat fermented foods: Fermented foods such as yogurt, sauerkraut and kefir all contain healthy bacteria, mainly Lactobacilli, and can reduce the amount of disease-causing species in the gut.
Limit your intake of artificial sweeteners: Some evidence has shown that artificial sweeteners like aspartame increase blood sugar by stimulating the growth of unhealthy bacteria in the gut microbiome.
Eat prebiotic foods: Prebiotics are a type of fibre that stimulates the growth of healthy bacteria. Prebiotic-rich foods include artichokes, bananas, asparagus, oats and apples.
Eat whole grains: Whole grains contain lots of fibre and beneficial carbs, which are digested by gut bacteria to benefit weight, cancer risk, diabetes and other disorders.
Try a plant-based diet: Vegetarian diets may help reduce levels of disease-causing bacteria such as E. coli, as well as inflammation and cholesterol.
Eat foods rich in polyphenols: Polyphenols are plant compounds found in red wine, green tea, dark chocolate, olive oil and whole grains. They are broken down by the microbiome to stimulate healthy bacterial growth.
Take a probiotic supplement: Probiotics are live bacteria that can help restore the gut to a healthy state after dysbiosis. They do this by “reseeding” it with healthy microbes.
Take antibiotics only when necessary: Antibiotics kill many bad and good bacteria in the gut microbiome, possibly contributing to weight gain and antibiotic resistance. Thus, only take antibiotics when medically necessary.
Extracts taken from Ruairi Robertson, PhD from https://www.healthline.com