Microbiome 101

Meet Your Microbiome

You are home to a community of trillions of microorganisms, including 38,000,000,000,000 (that's 38 trillion) bacteria, living in and on your body. The bacteria alone represent 50% of you by cell count.¹ Collectively, these microorganisms comprise your microbiota, and these trillions of microbial cells and all of their components and surroundings constitute your microbiome. The majority of these microbes reside in your gastrointestinal tract, but many others live in diverse places like your mouth, your skin, and your armpits, etc., each with their own unique microbiome.

Wait. 38,000,000,000,000 bacteria!?

Where does my microbiome come from?

Your microbiome begins developing at birth. During vaginal delivery, you're exposed to your mother's vaginal and fecal microbiota. Throughout infancy and childhood, your microbiome continues to develop through diet, environment, and interactions with family members and pets. By age 3, your microbiome resembles an adult microbiome and remains relatively stable throughout life, though it can be influenced by diet, antibiotics, illness, and lifestyle factors.

What do bacteria do in my body?

Gut bacteria perform numerous essential functions. They help digest food, particularly complex carbohydrates that your body can't break down on its own. They produce vitamins like vitamin K and B vitamins. They train your immune system to distinguish between harmful and harmless substances. They produce metabolites that influence your metabolism, mood, and overall health. They also compete with harmful bacteria, preventing them from colonizing your gut.

What is the gut barrier?

The gut barrier is a complex system that controls what passes from your intestines into your bloodstream. It consists of a single layer of intestinal epithelial cells held together by tight junctions, covered by a protective mucus layer. This barrier allows nutrients to pass through while keeping bacteria, toxins, and harmful substances out of your bloodstream. When this barrier becomes compromised (often called "leaky gut"), it can allow unwanted substances to enter your circulation, potentially triggering inflammation and immune responses.

Is my microbiome healthy?

A healthy microbiome is characterized by high diversity (many different species) and balance (no single species dominating). Signs of a healthy microbiome include regular bowel movements, good digestion, strong immune function, and stable mood. Factors that support microbiome health include a diverse diet rich in fiber, fermented foods, regular exercise, adequate sleep, and stress management. Conversely, frequent antibiotic use, poor diet, chronic stress, and lack of sleep can negatively impact your microbiome.

Citations

¹ Sender, R., Fuchs, S., & Milo, R. (2016). Revised estimates for the number of human and bacteria cells in the body. PLOS Biology, 14(8), e1002533.