Say Hello To Your Little Friends. What You Should Know about Gut Bacteria

Let's face it. We live in a world full of bacteria. From the food you eat to the door knob you just turned, these tiny critters are everywhere. Many people think of bacteria as dangerous and dirty, and I'm sure if you're the type who uses hand sanitizer every five minutes, you probably already feel creepy-crawly. While there are many bad bugs that can have serious health consequences, the bacteria in our gut play a critical role in keeping us healthy. These bacteria are our friends not our foes. 

The gut is one of the most complex ecosystems on the planet. In fact, your gut is home to trillions of bacteria. There are 10 times more microorganisms in and on our body than there are human cells! 10 times!! These tiny microorganisms, called intestinal flora, have many important functions, from supporting your immune system and digestive system to playing large role in our emotions and mental health. If you look after your little friends, you are guaranteed better health. Here's what you need to know about your microbiome. 

There are 10 times more microorganisms in and on our body than there are human cells! 


Your intestinal flora has been with you ever since you entered the world.  Prior to birth, every gut is sterile. But over time, everyone's gut develops a diverse and distinct brew of bacterial species, determined in part by genetics and in part by what bacteria live in and on those around us. If you were born vaginally, your first digestive bacteria was passed to you from your mother. If you were born by C-section, your first microbes came from the environment you were in. 

Microbial development is also affected by whether you were breast fed or bottle fed. Breast milk largely influences the composition of an infants’ gut microbiota as well as development of proper immune response to foreign invaders.  As we grow older, are introduced to solid foods, and exposed to different environmental agents, our microbiota changes and grows with us. 


Our digestive system is a lovely wet home and steady food supply for trillions of bacteria. In return, your bacteria digest substances our human bodies can't. The bacteria break down and thrive on the plant fiber we eat but otherwise cannot digest. This is why your body can digest that sandwich you had for lunch, and why it can extract the nutrition from the salad you had alongside it. 


The gut provides a the physical barrier between our insides and our outsides.  It’s specialized to absorb nutrients from the food we digest while keeping foreign substances out. In fact, 70-80% of our immune system resides in our gut!  A healthy microbiota, consisting of the right kinds and amounts of microbes, helps destroy drugs, toxins, and other foreign invaders. It protects us from infections, chronic inflammation, and possibly many immune-based disorders. 

70-80% of our immune system resides in our gut!

Our intestinal flora informs and influences our immune system.  By joining forces with your immune system cells, we are able to fight pathogenic invaders. Think of our gut flora like the bouncer at a club. Our gut flora cannot allow just anyone to penetrate the boundaries. When it does come across an invader, our flora signals the immune system to take action. This is basically the alarm sounding, telling the body that there is an intruder.

If, however, our intestine barrier somehow becomes structurally damaged, or if it’s abnormally permeable, foreign invaders may pass through and get into our bloodstream. This is often referred to as “Leaky Gut”.  


The gut has often been called our second brain. While many think of their brain as the organ in charge, your gut actually sends far more information to your brain than your brain sends to your gut. Just as you have neurons in your brain, you also have neurons in your gut. In fact, the greatest concentration of the neurotransmitter serotonin, which is involved in mood control, depression and aggression, is found in your intestines, not your brain.  About 95% of body's supply of serotonin is manufactured by gut bacteria. 

95% of body's supply of serotonin is manufactured by gut bacteria. 

You've probably experienced the sensation of butterflies in your stomach when you're nervous, or had an upset stomach when you were angry or stressed. The flip side is also true, in that problems in your gut can directly impact your mental health, leading to issues like anxiety and depression. Researchers now believe that bacteria in our digestive systems may help mold brain structure as we're growing up, and possibly influence our moods, behavior and feelings when we're adults. 


Your gut bacteria are vulnerable to your diet and lifestyle. If you eat a lot of sugar, refined grains, and genetically engineered foods your gut bacteria are going to be compromised. 

  • Preservatives: The purpose of preservatives is to kill the bacteria that make food spoil. When those preservatives enter your digestive system, they also kill the healthy bacteria in our gut.
  • Sugar:  Sugar promotes the growth of bad bacteria in the gut. Diets high in sugar, refined carbohydrates and processed foods basically provide an all-you-can-eat buffet for the bad bacteria to thrive.
  • Antibiotics: Antibiotic means "against life" in Greek, and antibiotics are designed to kill off bacteria but unfortunately they don’t discriminate between the good and the bad guys. When friendly bacteria die off bad bacteria take off, and can out number our friendly strains in no time. While antibiotics can be lifesaving, you shouldn't get into the habit of asking your doc for a prescription every time you sneeze. When your healthy bacteria are wiped out, you're at a higher risk for developing other illnesses. 
  • Antibacterial Soap: As a society we have become obsessed with cleanliness. These products often contain the antimicrobial chemical triclosan, which possibly could affect our microbial colonizers. 
  • Stress: Increased levels of stress shows both short- and long-term effects on the functions of the gastrointestinal tract and has a negative effect on your gut flora.


It can’t be overstated how our overall physical and mental health is dependent on our gut health. The good news is that we are in control of many factors that influence our gut health. Prioritize gut health through these four easy steps.

  1. Consume a whole foods diet free of toxins, pesticides, and chemicals. Limit your consumption of refined carbohydrates, sugar, and other processed ingredients.
  2. Reduce exposure to antibiotics and drugs. 
  3. Take measures to reduce daily stress. This can include yoga, meditation, or simply practicing mindful breathing. 
  4. Incorporate prebiotics into the diet such as raw asparagus or chicory root. Prebiotics simulate the growth of beneficial bacteria in the gut.
  5. Consume probiotics, such as those naturally occurring in fermented foods. Probiotics introduce healthy bacteria into the gut, helping to maintain its natural balance of gut microbiota.

These lifestyle changes will help maintain proper gut barrier function and a healthy gut microbiota. As Michael Pollan states in his recent book, 'Cooked: A Natural History of Transformation,' these bacteria are the key to a "grand unified theory of diet and chronic disease". We know enough now to say, when you're good to the microbiome, the microbiome is good to you.



Sources and References:

Changing gut bacteria through diet affects brain function, UCLA study shows. (n.d.).Newsroom. Retrieved July 14, 2014, from

Grenham, S., Clarke, G., Cryan, J. F., & Dinan, T. G. (2011). Brain-Gut-Microbe Communication in Health and Disease. Frontiers in Physiology,2. doi:10.3389/fphys.2011.00094

Lankester, J., Patel, C., Cullen, M. R., Ley, C., & Parsonnet, J. (2013). Urinary Triclosan is Associated with Elevated Body Mass Index in NHANES. PLoS ONE, 8(11). doi:10.1371/journal.pone.0080057

Purchiaroni, F., Tortora, A., Gabrielli, M., Bertucci, F., Gigante, G., Ianiro, G., … Gasbarrini, A. (2013). The role of intestinal microbiota and the immune system. European Review for Medical and Pharmacological Sciences, 17(3), 323–333.

Stein, R. (2013, January 1). Gut Bacteria Might Guide The Workings Of Our Minds. NPR. Retrieved July 14, 2014, from