When you think of bacteria, you’d typically think of pathogens such as Streptococcus pyogenes, which gave you a strep throat infection last winter or the latest E. coli outbreak in lettuce or meat in grocery stores. We hear about bacteria most often in negative contexts such as the doctor’s office and news articles in hysterics. However, microbes are absolutely essential to our livelihood and work tirelessly to protect us from infection and disease. In fact, microbes outnumber human cells on your body 10-1 according to the National Institute of Health. The collection of microorganisms on your body is collectively known as the “microbiome.” Everyone’s microbiome is unique and changes based on geography, diet and any number of factors. Currently, the Human Microbiome Project is underway to get a better understanding of beneficial human bacteria.
Newborns are introduced to beneficial microbes through the placenta, during delivery, and through breastmilk. In the first year of a newborn’s life, their microbiome changes drastically as their bodies work to create an effective defense against pathogens and disease. Your mom’s transmission of these microbes is essential to the development of a healthy immune system and long-term gut disease prevention (Seriously, thank your mom for that next mother’s day!) These beneficial microbes are only passed along during vaginal delivery, so research is being done on how the microbiome changes due to natural or cesarean section delivery. Since being a newborn, your microbiome is constantly changing and becomes similar to those around you.
You’ve probably been prescribed antibiotics for various bacterial infections throughout your life thus far. Antibiotics are meant to be prescribed to be as specific as possible to the pathogen infecting your system, but in a lot of cases many beneficial bacterial species are eradicated from your microbiome than expected. Antibiotics help your sore throat heal quickly, but have lasting effects on the microbiome. A stanford experiment found that after antibiotics were administered, gut bacteria largely recovered after a month, but some species were still absent 6 months after the antibiotics was administered. Antibiotics significantly alter the populations of beneficial gut bacteria in our systems, which can be detrimental long-term. For this reason, probiotics and other mechanisms to reintroduce microbes to the gut after antibiotics are being extensively studied.
One of the most important components to the composition of the microbiome is your diet. The makeup of the food you eat has a large effect on which microbes live in your digestive tract. According to a Time Magazine article on the microbiome, diets that are high in sugar deplete the diversity of the microbiome within a week. There are notable differences in the microbiome diversity of people with a typical western diet, heavy in carbs, fat and protein compared to other places in the world where the typical diet is rich in fiber and antioxidants. Diet quickly has an effect on the microorganisms that colonize a particular person but poor diet can limit diversity. A microbiome that has a large diversity can use more energy sources as food and effectively fuel your immune system.
Why should you care about these organisms you can’t even see?
The bacteria that beneficially colonize your body are essential to your immune system function and nutrition. Research has been done that links poor gut microbial diversity to increased susceptibility to Type 1 diabetes, muscular dystrophy, fibromyalgia and other autoimmune diseases. Digestive conditions such as Crohn’s Disease and Inflammatory Bowel Syndrome are in increasing rates of diagnosis in Western countries for these same reasons. In addition, the microbiome is linked to higher rates of obesity due to less efficient harvesting of calories.
The discovery of the microbiome began in the 1990’s so it is an incredibly new idea to think of the microbes that colonize us as their own organ. Bacteria are not always invaders to eradicate; they coat our bodies, boost our immune system and protect us from disease. The microbiome is its own diverse community which needs to be healthy to function properly. Bacteria are not simply pathogens; we are their environment.
Take care and appreciate your microbiome!