How ‘Good’ And ‘Bad’ Bacteria Get Into Your Gut

Dr. Adrian Pujayana

MICROBES are non-human cells that live and function all around us, on us and in us. Inside our body live an estimated 100 TRILLION microbes, about three times the number of human cells that make up the form and structure of the human body. However, despite their numbers, microbes compose only about 1 percent of the total mass of the body! Though outnumbered, humans have the advantage of being a responsive host capable of change … when we want to, that is.

Between 2013 and 2017 there were nearly 13,000 published scientific articles on microbes and bacteria, accounting for about 80 percent of all such articles from the prior 40 years! Much has to do with the development of genetic tools and analytical methods available to scientists, and over the next few years, will allow scientists a chance to interpret the blossoming amount of data into useable practices, make predictions and identify possible threats to our health.

There are too many species and sub-species of bacteria that reside on or in our body to mention here, and all across the globe, healthy people appear to have similar bacterial profiles in their skin, hair, oral cavities and in the gut.  Most of the bacterial dominance in type and number are present in our gut, and over the last decade, scientists have noticed that these non-human species of bacteria interact and communicate with their human hosts, influencing critical functions of the hosts’ immunity, neurology, and metabolism.  

How Did They Get Into Us?

A child is born into a world full of bacteria, starting with the birth process, where contact with the mother during vaginal birth introduces the infant to the first cultures, which are far different (and absent) during a Caesarian section. Nursing and breast-feeding provide additional early exposure to bacteria that will later contribute to the development of the immune system and influence the central nervous system.

Over the years, microorganisms enter and colonize in our gastrointestinal tract mainly by food sources. Bacteria that are in dirt, in milk and on plant surfaces enter our body and have to fight for the space to reside within our body. Many variables influence a bacteria’s ability to thrive, such as the presence of sugar, artificial or manufactured food products, illness, dietary diversity and frequency of bowel movements. Even the presence of other bacteria will make or break new colonies from living mutually inside the host. 

An Amicable Symbiosis

With continued advancement in genetic tools comes our ability to differentiate the kinds of bacteria present inside us during different states of health. For example, some species of bacteria may be metabolizing the drug compound L-Dopa in the gut before it can reach the brain to be metabolized by the brain into dopamine. The lack of dopamine in the brain has been associated with Parkinson’s tremors and other neuro-degenerative disorders. 

You Are Never Alone

The collection of microorganisms that lives within your GI tract forms a “microbiota,” outnumbering the amount of cells of your body composition by three to 10 times. The diverse collection of genetic material between them is known as the microbiome. Laboratory rats deprived of microbiota and living in sterile conditions have many health problems. Their bones are too flexible, they don’t digest their food well, cannot form endogenous vitamins and proteins on their own and die of early degenerative diseases.

Future Relationships

The symbiotic relationship between microorganisms and humans is essential, and can be beneficial or toxic to our health. We don’t know how many other species we will discover in the near or distant future, and to what degree of impact they will affect or be associated with human diseases. And the ones we do know about, the “good” and the “bad” bacteria that are in us, we are still learning from. They need us as much as we need them, as more and more studies confirm. 

What we do know is that a diversity of whole-food consumption is essential to balancing our microbiota, and that manufactured foods high in sugars and artificial products can cause certain bacterial cultures to thrive and others to dwindle. Changing our GI microbiota is not impossible, as they got to where they are through our foods and products we consume.

So the next time you have a bite to eat, remember that you are a host to millions of guests. Some will stay, some will go. Being more selective as a host may perhaps prevent the guests from destroying the house over time! 

Dr. Adrian Pujayana has been providing drug-free solutions for health and wellness to adults, athletes and youth since 2000 through his private practice at Family Chiropractic Center of South Pasadena, a place for strength training and nutrition-based health care. For comments or questions, email him at