We have talked about our microbiome in previous science posts, and how our health can be influenced by it. Just by following The Livy Method for these last 12 weeks, has had a major influence on our gut health and microbiome. In fact, as some of us head into maintenance, eating what makes us feel good, reinforces eating the foods that feed these good bacteria, continuing to keep us healthy. In this final science post, let’s review all that we have discussed about the microbiome and then take a deeper dive into it.
The microbiome- a review
According to the National Institute of Environmental Health Science (NIEHS) in the United States, the microbiome is defined as the collection of all microbes, such as bacteria, fungi, viruses, and their genes, that naturally live on our bodies and inside us. Bacteria, viruses, fungi and other microscopic living things are referred to as microorganisms, or microbes, for short. Although microbes are so small that they require a microscope to see them, they contribute in big ways to human health and wellness. They protect us against pathogens, help our immune system develop, help to produce vitamins that our body needs, and enable us to digest food to produce energy.
Because the microbiome is a key connection between the body and the environment, these microbes can affect health in many ways and can even affect how we respond to certain environmental substances. Some microbes alter environmental substances in ways that make them more toxic, while others act as a buffer and make environmental substances less harmful.
How can the microbiome affect health?
More than 2,000 years ago, Hippocrates, the Greek physician who many attribute as the founder of modern medicine, suggested that all disease begins in the gut. It turns out he was onto something (Gunnars, K., 2019, February)!
Studies examining the diversity of the human microbiome started with Antonie van Leewenhoek, who, as early as the 1680s, had compared his oral and fecal microbiota (What is Biotechnology?). He noted the striking differences in microbes between these two habitats and also between samples from individuals in states of health and disease in both of these sites. Thus, studies of the profound differences in microbes at different body sites, and between health and disease, have existed since the science of microbiology itself. What is new today is the ability to use scientific techniques to gain insight into why these differences exist, and to understand how we can affect transformations from one state to another.
The human microbiome has a different community of microbes located in different areas in the body. Trillions of these microbes exist mainly inside your intestines and on your skin. Most of the microbes in your intestines are located in the large intestine in an area called the cecum, and they are referred to as the gut microbiome. They are also found in other areas of the body such as the oral and nasal cavities, and the conjunctiva of our eyes.
According to Gunners (2019, February), although many different types of microbes live inside you, bacteria are the most studied. In fact, there are more bacterial cells in your body than human cells. It is estimated that there are roughly 40 trillion bacterial cells in your body and only 30 trillion human cells. That means you are more bacterial than human!
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 and are considered as an extra organ in your body, playing a huge role in your health.
The microbiome and digestion
Humans have evolved to live with microbes for millions of years. During this time, microbes have learned to play very important roles in the human body. In fact, without the gut microbiome, it would be very difficult to survive. Interestingly, the food you eat affects the diversity of your gut bacteria.
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. Interestingly, on average a person carries about 160 species in their gut.
As discussed in the science post The Basics of Digestion, the gut flora in our colon help to ferment the indigestible food and produce vitamins such as Vitamin K and B vitamins that are reabsorbed by the colon. But that’s not all, an estimated 80% of our immune system is found in our gut. Having a healthy digestive system, which includes a good balance of our healthy gut flora, ensures a healthier immune system and better nutrient absorption. This is why the Livy Method recommends taking a good quality probiotic, along with a prebiotic (if needed), to help feed those good microbes. Eating the high fibre, nutrient rich foods on plan not only gives our body what it needs, but is also vital in supporting our gut flora!
A person’s core microbiome begins to develop from birth and is formed in the first years of life, but can change over time in response to different factors including diet, medications, and environmental exposures. You are first exposed to microbes when you pass through your mother’s vaginal canal. However, new evidence suggests that babies may come in contact with some microbes while inside the womb.
Breastfeeding introduces beneficial bacteria to a baby’s gut which also contributes to their microbiome. 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.
Differences in the microbiome may lead to different health effects from environmental exposures and may also help determine individual susceptibility to certain illnesses. Environmental exposures can also disrupt a person’s microbiome in ways that could increase the likelihood of developing conditions such as diabetes, obesity, cardiovascular and neurological diseases, allergies, and inflammatory bowel disease.
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 are called Bifidobacteria. They digest the healthy sugars in breast milk that are important for growth.
Influencing your immune system: The gut microbiome also influences how your immune system works. By communicating with immune cells, the gut microbiome can influence how your body responds to infection.
Influencing your brain health: Some research suggests that the gut microbiome may also affect the central nervous system, which controls brain function. See below for more details.
Digesting fibre: Certain bacteria digest fibre, producing short-chain fatty acids in the gut, which are important for gut health. Fibre may help prevent weight gain, diabetes, heart disease and the risk of cancer.