Gut microbes can be sensitive little critters. And they can be easily disrupted by environmental contaminants.



Children’s bodies are exposed to more toxins now than ever before. These external influences can impact not only childhood development and physiology, but also the underlying gut microbiota itself.


Although we are just beginning to explore the role of toxins in determining the gut microbial ecosystem in kids, it is clear that there are 5 microbe disruptors that really pack a punch. Here they are:


1. Antibiotic Use 


We all know that antibiotics are being over-prescribed. And we now know that the dangers of antibiotic overuse go beyond antibiotic resistant bacteria. Antibiotics, especially in the earliest years of life, have been found to profoundly alter the microbial landscape.


Ampicillin and penicillin in particular are two commonly used antibiotics that change the ecology of the microbtioa. They do this both by directly reducing the number of targeted bacteria and inhibiting competition among species (which favors certain non-targeted species). Their pervasive use makes way for the proliferation of harmful bacteria like Clostridium difficile and Escherichia coli.



2. Pesticide Exposure



Organophosphate pesticides are being used around the homes, schools, and play areas of children like never before. That perfectly green and grassy yard comes at the cost of children’s health.


Certain herbicides and insecticides, namely glyphosate and chloripyrifos, have been shown to substantially decrease numbers of Lactobacillus spp., Bifidobacterium spp., and Enterococcus spp., contributing to dysbiosis in the gut microbiota.


Likewise, pesticide use has recently been shown to alter the oral microbiome of farm workers. Conventional farmers therefore have the potential to have far less oral microbial diversity over time than non-farmers.


3. Heavy Metals



Heavy metals are ubiquitous in today’s post-industrial environment, and chronic low-level exposures are increasingly common. The gut microbiome impacts of recurrent heavy metal exposures are complex. Nonetheless, it is clear that heavy metals can have an effect on microbial communities. For example, mercury exposure has been correlated with both a greater abundance of mercury-resistant bacteria and a complete elimination of Bacteroidetes spp. in the mammalian gut. The full breadth of health consequences of this are still being explored.


Interestingly, in one recent study daily consumption of probiotics in yogurt (specifically Lactobacillus rhamnosus GR-1) were actually found to have a protective effect against increased blood mercury levels in pregnant women. This phenomenon demonstrates well the role of probiotic-mediated detoxification in microbial medicine.



4. Poor Diet



Our food is one environmental factor that has changed dramatically over the past century. As a result, the human microbiome has altered significantly. The western diet which is high in processed foods and refined carbohydrates, and low in dietary fiber intake, wreaks havoc on gut microbtioa.  In fact, in a recent review paper comparing the affects of diet on human gut microbiota, it was found that the American diet (i.e. a western diet) resulted in the least microbial diversity of any group studied.


When this cross-cultural analysis was examined further, the authors also found that certain bacterial genera (namely Prevotella) were in great abundance in several rural African populations in Tanzania, whose diets are dominated by high fiber and complex carbohydrates. It all goes to show that the food we eat serves not only ourselves, but all the microbes we play host to.



5. Maternal Stress


Modern motherhood is full of challenges, and lots of stress. This chronic psychological stress can impact not only the mother’s microbiota, but also her child’s. For example, maternal stress has been associated with altered vaginal immunity and reduced numbers of Lactobacillus. This reduction in Lactobacillus bacteria translates to inadequate inoculation of a  newborn with this beneficial microbe which may play a crucial role in brain and sensory development in children.

By association then, maternal stress over time can alter the pediatric microbiome making children more susceptible to neurodevelopment disorders, like Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD).






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Finlay, B. B., & Arrieta, M. C. (2016). Let Them Eat Dirt: Saving Your Child from an Over-Sanitized World. Random House.


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Jašarević, E., Howerton, C. L., Howard, C. D., & Bale, T. L. (2015). Alterations in the vaginal microbiome by maternal stress are associated with metabolic reprogramming of the offspring gut and brain. Endocrinology156(9), 3265-3276.


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Stanaway, I. B., Wallace, J. C., Shojaie, A., Griffith, W. C., Hong, S., Wilder, C. S., … & Vigoren, E. M. (2016). Human Oral Buccal Microbiomes Are Associated with Farmworker Status And Azinphos-methyl Agricultural Pesticide Exposure. Applied and Environmental Microbiology, AEM-02149.