The modernization of our society has changed many aspectsof how we live our day to day lives—but it’s safe to say that once we change theexternal, the internal can change too! The earth is experiencing what we now classifyas an Anthropocene; the global time period from which humans have taken overthe Earth. From damaging our ecosystems with the industrialization of cities,to the destruction of the ozone layer, our activities have altered naturalprocesses such as climate change and the “way nutrients move in our ecosystem,such as nitrogen and phosphorus”. Over the past few centuries, humans havefought an ongoing battle to defeat germs and bacteria.
Despite our pronouncedefforts to improve sanitation and free ourselves from disease—medical establishmentshave seen the contrary—”A staggering increase in allergies and autoimmunediseases in the industrialized world.” While some like to blame that we wereonce deprived of the necessary bacteria to develop our immune systems aschildren—this theory lacks hard evidence between the exposure to pathogens andimmunological response systems. With our growing knowledge on microbial healthand the numerous studies conducted, researchers have come up with a bettertheory that does not blame one factor to the rise of allergy and disease but all factors—the “disappearingmicrobiota” theory. This theory takes into account all the ways we havemodernized our society and how it has potentially affected the health of ourmicrobiomes. Pollution, modern birth practices, exposure to antibiotics and moderndietary patterns are a few of the many factors that have contributed toaltering our microbial systems. When our gut health suffers, our bodies are notproperly equipped with enough of the healthy microbes to fight off whateverwants to attack. External factors in the environment (such as the onespreviously listed) have also been accounted for in altering the composition ofour microbes. This in turn, depletes us from reaping the benefits of what oncewas a symbiotic relationship between the human and its gut microflora.
IncreasedAntibiotic UseAccording to a CDC publication made in 2016 in reference to datafrom the Journal of American Health Association (JAMA), at least 30 percent ofantibiotics prescribed in the United States are unnecessary.Even more surprisingly, a recent publication made by the WHO (World HealthOrganization) on January 29th, 2018 revealed a study that demonstratedhigh levels of antibiotic resistance worldwide.Resistance was found in 500,000 people amongst 22 countries. If this stilldoesn’t surprise you, most of these new resistant strains of bacteria areamongst the most common and potentially dangerous such as Escherichia coli, Staphylococcus aureus, andSalmonella spp.So whatdoes this indicate?We aremisusing and overusing antibiotics.
As a result, our microbiomes are gettingweaker, the bacterial infections are getting stronger, and we are now moreprone to infection—infection that will be a lot harder to fight off than before.Recovery of the gut microflora from antibiotic treatment can take an extensiveamount of time depending on the type of antibiotic being used. Conclusively, antibioticsshould only be used when necessary to avoid the further deterioration of ourgut microflora and the development of more antibiotic-resistant strains ofbacteria.ObesityEpidemic with Diet patternsOur society has experienced a large spike in obesity worldwide alongwith its associated disorders. While sedentary lifestyles and excess calorieintake have gotten must of the bad wrap, our microbiota hasn’t been getting any!The truth is, studies have shown a strong link between obesogenic diets and thenegactive impact it plays on our microbiomes. “Changes in diet can account for57% of the variations in microbiota.” A study was conducted by Turnbaugh et al.
on mice gavaged with human feces to study the correlation between diet and thehuman microbiota. The study consisted of two groups of mice—one group fed avegetarian diet and the other a western diet consisting of high-fatty foods.Results proved that the mice fed with the western diet had increased numbers ofbacteria associated with the Firmicutesphyla and a large decrease in one of the four most dominant bacterial phyla in thehuman gut–Bacteroides spp.
The shiftin gut community for mice being fed the Western diet was evident, so much so,scientists were able to notice within a day.So what? We get a new phyla of gut bacteria with a new diet—but whatharm can the change of composition of a microbe do to our bodies?It’s important to really consolidate the fact that gut bacteriasuch as the Bacteroides spp. are dominant for a reason, they are meant to regulatecertain processes in the body and any change in composition to the naturalorder in which our body is meant to run can mean serious implications on ourhealth. Here’s why….The Bacteroides spp. is responsible for producing GLP-2, anintestinal peptide that prevents lipopolysaccharide (LPS) from entering ourplasma by protecting the gut and making sure food is digested properly. Withdecreased levels of GLP-2 caused by the Firmicutesphyla, we are likelier to get higher levels of LPS plasma concentration andwhat we now know as a “leaky gut”. Aleaky gut can translate to serious health complications, as the increasedpermeability of the gut (the “leakiness”) may permit toxins to flow out of ourintestines and into our blood stream!It is important we keep ourselves properly informed on howobesogenic diets affect not just our weight and energy levels but also ourmicrobiomes.
A simple change in the composition of our microbes can be one ofthe leading resulting causes of disease in obese individuals.Caesareanbirths—Modern day birth and its effect on our microbiomeNew research has also demonstrated how modern birth practices aredepriving offspring of necessary microbes normally obtained through vaginalbirths. “The necessary microbes destined for the gut microbiota originate fromthe maternal birth canal and rectum.” A newborn conceived through Caesareansection will miss out on these microbes and will instead receive its gutmicrobes from the mother’s skin and hospital environment.
Consequently, hoursand days after the newborn is conceived, a newborn conceived through Caesareansection is likelier to be exposed to unfamiliar possibly even harmful bacteriathat can pose a threat to the newborn’s undeveloped immune system. The newbornwill also be deprived of healthy probiotic bacteria normally obtained afterconception through traditional birth practices that is critical to thedevelopment of the immune system. These critters won’t arrive until much laterand in smaller quantities for caesarean section babies. Conclusively, modernbirth practices can pose a real threat to the immune system of newborns due tothe deprivation of important gut bacteria obtained through traditional birthpractices.PollutionFinally, we have pollution—one of the most obvious of the four. Itis pretty obvious to see the effects on how industrialization has done itscollateral damage–from carbon emissions to industrial waste to harming the ozonelayer, not only are we polluting the external world but also our internal worlds.Our microbiomes have been greatly affected by the pollution of our Earth. Forpurposes of keeping things short, I will only focus on air pollution,specifically a key component which has done a great deal of harm to ourmicrobiomes.
“Air pollution consists of a heterogenous mixture of differentsubstances, including gases.” This key pollutant that has greatly affected ourmicrobiomes has been the exposure to Particulate matter (PM). Studies haveshown that the inhalation of Particulate matter is discarded from the lungs andinto the intestine. PM has also polluted our food and water supply, causingeven more damage to our intestine.
Ingestion of PM has also demonstrated itseffects on changing the composition of gut bacteria—a study conducted on miceresulted in dereased amounts of of Bacteroidetes, Firmicutes, and Verrucomicrobia as well as changesin the short chain fatty acid production. Not only does it change our microbes but studieson Particulate matter have reported to have significant effects on increasingintestinal permeability—this can lead to inflammation of the gut and result indiseases such as IBD.