When was the last time that you encountered microorganisms? Perhaps in a high school biology class, a doctor’s office or a dorm shower? Take a deep breath, expand your lungs with fresh air and slowly exhale to truly consider the scale of this question.
Believe it or not, you incorporated 100,000 different microbes into your body in the single breath you just took. Every interaction you have with the Earth involves an exchange with miniscule creatures invisible to the naked eye. Typically, we consider microorganisms as part of our outside environment; however, our human bodies actually house trillions of these life forms. Our molecular breakdown is 90 percent microbial, and a mere 10 percent human.
Though we often imagine bacteria as deleterious assaults waiting to infiltrate our bodies, not all bacteria are dangerous. Consider your skin: a massive layer cloaked in a variety of beneficial bacteria that protect the body from environmental pathogens. This dynamic, defensive team contains many players that secrete antimicrobial peptides to prevent other microbes residing on the body. The ensemble also houses certain bacterial strains that thrive in the acidic, superficial layers of our skin and prevent pathogens from readily attaching to our body surfaces. Our active microbial soldiers tirelessly toil and patrol the skin to keep us healthy.
In addition to our skin partners, our gut microbiome is crucial to human survival. A burgeoning ecological community of bacteria coats our intestines, and these critters have an overwhelming impact on our health.
On their own, humans are unable to produce or uptake Vitamin K. However, thanks to our microbial buddies, we receive a constant supply of this essential mineral. Similarly, our gut microbiome — often referred to as a “newly discovered organ” — helps us digest certain complex food molecules down into constituent particles.
Without a hearty gut flora, humans run into major problems. Recently, scientists have discovered that disorders related to cancer, diabetes, mental health, autism, obesity, acne, autoimmune diseases and gastric ulcers are all related to the robustness of our gut microbes. These bacteria play such a vital role in maintaining human vitality that the gut composition is becoming a major predictor of our lifelong history.
Since our body is so heavily composed of beneficial bacteria, antibiotics inadvertently target some of these positive microbes and can seriously disrupt our innate, fragile bacterial ecosystem. The most frightening aspect of frequent antibiotic use is that once our natural microbe balance is perturbed, there is no guarantee that all the lost species will return. Other opportunistic good bacteria can take over instead, preventing older residents from re-establishing themselves. This process can be hard on the body because it requires continual readjustment to colonizing microbe species and can result in low species diversity if a particular species dominates the body more so than before.
Though developing antibiotic resistance is a popular media concern to the overuse of these drugs, the “missing microbes” effect of antibiotics can have more devastating effects. In its natural state, the human body cannot function properly without its trillions of microbial friends. The next time you are prescribed antibiotics, think deeply about the impact it will have on your microbiome before you swallow a pill.
Nikita Deshpande is a rising sophomore in the College. Microbial Explorations is published every other Wednesday.