The debate continues over whether everyday household products are negatively impacting our health through their effects on our gut microbiomes.
Understanding of the gut microbiome, the unique collection of hundreds of microbial species numbering in the trillions that inhabit our bodies and our intestines in particular, is a relatively new and emerging field of scientific study. A growing body of research suggests that the makeup of one’s gut microbiome may have far reaching health impacts for individuals.
“Scientists now have evidence that intestinal bacteria may have metabolic, cardiovascular, autoimmune and neurological impacts,” said Christopher Gaulke, a postdoctoral microbiology researcher in the Oregon State University (OSU) College of Science.
The gut-associated microbiome performs vital functions for human health, prevents colonization with pathogens, stimulates the development of the immune system, and produces micronutrients needed by the host. Dysfunction of this microbiome has been associated with human disease, including diabetes, heart disease, arthritis and malnutrition.
While scientists are just beginning to identify the connection between health and the intestinal microbiome, there are also growing concerns regarding how this system, sometimes referred to as the ‘forgotten organ’, is impacted by the food we put in our bodies and the products we put on them.
In a recently published study in the journal PLOS ONE, Gaulke and colleagues present findings that suggest triclosan, a common antimicrobial and antifungal agent found in many everyday items from toothpaste and socks to cutting boards and toys, can drastically alter gut microbiomes.
“Concerns about overuse of these agents are valid,” said Gaulke, the lead author of the study. “Cumulative impacts are also possible. We need to do significantly more evaluation of their effects, some of which might be dramatic and long lasting.”
In the study, researchers found that triclosan exposure was significantly linked to rapid changes in both the diversity and composition of the microbiome in 45 zebrafish, which researchers believe are an important animal model to help determine possible human biological and health impacts of this antimicrobial compound, according to media release by the university.
According to the university, triclosan was first used as a hospital scrub in the 1970s and is now one of the most common antimicrobial agents in the world. It is particularly common among personal care products such as shampoos, deodorants and mouthwashes — a point of significant concern considering it is also easily absorbed through the skin. Remnants of triclosan appear in urine, feces and breast milk and it has been associated with endocrine disruption in fish and rats, may act as a liver tumor promoter, and can alter inflammatory responses.
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Other research on the gut microbiome has suggested that imbalances can contribute to obesity and allergies among other complex conditions.
"There has been a legacy of concern about exposure to microbial pathogens, which has led to increased use of these antimicrobial products," said Thomas Sharpton, an assistant professor of microbiology and statistics in the OSU Colleges of Science and Agricultural Sciences, and corresponding author on the PLOS ONE study.
"However, there's now a growing awareness of the importance of the bacteria in our gut microbiome for human health, and the overuse of antibiotics that can lead to the rise of 'superbugs.' There are consequences to constantly trying to kill the bacteria in the world around us, aspects we're just beginning to understand."
The researchers acknowledge that it is not entirely clear what the implication may be for animal or human health, but scientists believe that compromising the bacteria in the intestinal tract may contribute to the development or severity of disease.
In contrast, a similarly recent study conducted by researchers from Stanford and Cornell suggests that triclosan does not have major impacts on our internal microbial communities.
According to the American Society for Microbiology, Stanford researchers had 13 healthy individuals use household and personal care products (toothpaste, hand soap, and dishwashing liquid) that either contained triclosan or did not contain triclosan for four months. While triclosan-containing products had a significant impact on the levels of triclosan found in urine, exposure to triclosan did not have a significant impact on the oral or gut microbiome or on a panel of metabolic markers.
The study, published in mSphere, was performed in humans rather than zebrafish, and just 13 participants were tested. Additionally, the study’s authors acknowledge that administration of the household and personal care products was imprecise.