The Gut Health Series: What is the Gut Microbiome?

You hear about the importance of gut health all the time. You are familiar with probiotics, maybe even prebiotics. But do you understand why our microbiome is essential for our health – or even what it is? The Gut Health Series will focus on gut basics – starting with today’s topic: what exactly is the microbiome, and what role does it play in our health?

What is the microbiome?

When we talk about the microbiome, we are referring to all the critters that live in and on us. We are virtually more microbes than human in that microbial cells outnumber our own by a nearly 10:1 ratio, and approximately 10 trillion reside in our body. Of the trillions of microorganisms that share our real estate, the majority inhabit our gut, where an estimated 3-5 pounds of bacteria, fungi, archaea, and protozoa live. 

What role does the microbiome play in our health?

Beyond keeping our digestion on track, our gut microbiome may play a role in many other vital functions in our body, including:

• Protection against pathogens and unfriendly bacteria 

• Inflammation reduction

• Synthesis of specific vitamins and short-chain fatty acids

• Protection of gut lining

• Communication via the gut-brain axis

• Regulation of metabolism

As nearly 70% of our immune cells reside in our gut, it’s no wonder the health of our gut influences our overall wellness . As we continue to work to understand the complexities of our microbiome, we are finding links between chronic diseases and gut health with conditions such as autoimmune disease, allergies, increased food reactivity, metabolic or endocrine disorders (type 2 diabetes, heart disease, PCOS, and obesity), and even skin conditions. There is also a direct communication link between your gut and brain (the gut-brain axis) where our microbiome can influence our mood and brain function. 

What influences the health of our gut?

If you are convinced that the health of your gut matters (and you should be), you can now focus on what steps to take you can take to support your microbiome. 

The initial colonization of the microbiome starts at birth when a baby moves down the birth canal and is exposed to the mother’s flora. If a baby is born via C-section, the initial microbe exposure will be whatever bacteria happens to be present in the delivery room, or on the hands of the person delivering the baby. Recent research suggested that perhaps the baby was exposed to mom’s microbiome in the placenta, but the data turned out to be a result of lab contamination. A baby is also exposed to healthy bacteria from mom during breastfeeding. 

The baseline microbiome is set around two years of age – but the population will continue to change over a person’s lifetime. After the initial colonization, the major influences of gut health are both environmental and social. For example, if mom receives antibiotics at birth, or if baby requires antibiotics early in life, the microbiome swiftly changes. Other factors that influence the health of our gut microbiome include:

• Lack of exposure to dirt and overabundance of cleanliness (“hygiene hypothesis”)

• Chronic stress

• Medications (ex: aspirin, antibiotics, acid blocking)

• Cigarettes and alcohol

• Low stomach acid

• Illness such as stomach flu, food poisoning, parasites, etc.

Can diet help our microbiome?

But there is good news. The number one factor influencing the health of our microbiome is our diet. Diet strongly affects the diversity and population of bacteria. While we are still learning more about the microbiome every day, we do know that a healthy gut appears to have an abundance of many different types of bacteria that all play important roles. Some bugs may support a healthy weight, while others help with digestion and vitamin synthesis. The food you eat will influence whether or not these bugs are healthy and happy.

In part two of the gut health series, we will focus on how to shape our gut microbiome through food - stay tuned.