The gut microbiome is made of trillions of organisms – bacteria, viruses, protozoa, and fungi and their collective genetic material – that live in your intestinal tract. In fact, there are more cells in this microbiome than there is in the rest of you, and their genome is about 100-150 times larger than your own. The composition of your microbiome is unique as a fingerprint and is shaped by early life, diet, and environmental exposures over time.

So, what does it do and why is it important?

The bacteria in our microbiome help digest our food, process nutrients, make vitamins B and K, and produce immune molecules that fight infection and heal wounds. They also produce neuroactive compounds, including 90% of the neurotransmitter serotonin, which regulate our emotions.

Your microbiome influences your immune system. 70% of your immune system lives and functions in your gut and is your first line of defense in protection against disease. Our immune system has coevolved with the gut flora and this interaction starts at birth and continues throughout our lives. A healthy crosstalk between the two, supports protective responses against pathogens (the “bad” microbes), promotes tolerance to harmless microbes and their products, and helps maintain self-tolerance (the ability of our immune system to not react harmfully to our own body). When there is dysbiosis, or an imbalance in the microbiome to more harmful flora it creates a “leaky gut.”  This destroys the lining of the gut allowing large molecules and harmful microbes to cross into the body causing chronic inflammation and altering our immune response. This then may allow autoimmune diseases like type 1 diabetes, rheumatoid arthritis, Crohn’s disease, ulcerative colitis, muscular dystrophy, multiple sclerosis, and fibromyalgia to develop. The wrong flora in your gut may contribute to obesity which can lead to and promote a variety of diseases and hormonal imbalances. In contrast, the beneficial bacteria may help calm inflammation and have been found to help in conditions like allergies, asthma, and eczema.

Your microbiome has an effect on your brain.  We already know neurotransmitters and other neuro active compounds are made by the microbiome, but it may also affect the brain via the enteric nervous system – your second brain. The enteric nervous system are millions of neurons that travel throughout your intestinal tract. There is bidirectional communication between the enteric and central nervous system (brain and spinal cord) creating the gut brain axis. Via this communication our microbiome shapes the architecture of sleep and stress reactivity, and influences memory, mood, and cognition. Alterations in your microbiome cause inflammation not only locally, but elsewhere throughout your body and central nervous system.  They may also produce neurotoxins. These changes have a role in the development of Alzheimer’s disease, autism, epilepsy, and mental health disorders (depression, anxiety, bipolar, schizophrenia).

Your microbiome may affect your cardiovascular health.  Certain bacteria may produce a compound call trimethylamine (TMA) which is a precursor to trimethylamine-N-oxide (TMAO).  Elevated levels of TMAO are linked to worsening coronary artery disease and heart failure.  The good bacteria in your gut produce short chain fatty acids that help regulate glucose metabolism, appetite regulation, and obesity which may be protective for the heart.

As you can see, the microbiome is essential for your health and alterations in it may cause disease.  You are able to improve your microbiome in a number of ways:

  • Limit sugar and artificial sweetener intake (it promotes the growth of unhealthy bacteria).
  • Eat more fruits and vegetables, especially those high in fiber.
  • Get more prebiotic and probiotic foods in your diet.
  • Eat foods rich in polyphenols (green tea, dark chocolate – at least 70% cacao, blueberries, pomegranates, nuts, seeds, olive oil)
  • Eat whole grains (labels are tricky, if you are able to roll your bread into a ball, it’s not a whole grain).
  • Breastfeed for 6 months.
  • Eat a diverse range of foods, this leads to a diverse microbiome which is an indicator of good gut health.
  • Be mindful of antibiotics.

Prebiotics versus Probiotics