OCT 02, 2023 7:38 AM PDT

Testing the 'Grandmother Hypothesis' & Variations in the Skin Microbiome

WRITTEN BY: Carmen Leitch

Kids are told to scrub behind their ears and between their toes, and for good reason. New research has investigated the skin microbiome of humans - the microbes that we carry around on our bodies - and they have found that the composition of the skin microbiome can vary considerably depending on the location, and the oil and moisture content of the site. The findings have been reported in Frontiers in Microbiology.

Image credit: Pixabay

In this study, the researchers wanted to know more about whether the skin microbiomes of healthy people conformed to what they termed "the Grandmother Hypothesis" for this study. His grandma always told her grandkids to make sure that they scrubbed behind their ears, between their toes and in their belly buttons, noted study co-author Keith Crandall, Director of the Computational Biology Institute and a professor of biostatistics and bioinformatics at George Washington University. The idea was that areas that are tucked away, and tend to not get washed as often would be bacterial hotspots.

The investigators recruited a group of 129 healthy students to collect data from their own bodies; they took swabs of the oily and moist areas between their toes, behind their ears, and in their belly buttons. Other samples were also taken from less oily or moist areas such as forearms and calves, which are also usually washed more frequently, to serve as controls.

A metagenomics approach was then taken, and the students extracted all of the DNA from their samples, which was then sequenced. The results of the sequencing were compared to databases so that the bacterial species within could be identified. This showed that forearms and calves tended to carry a more diverse group of microbes, which is considered to be a sign of a healthier microbiome, compared to the moist hotspots, which had less diverse bacteria.

If nasty microbes become dominant in a microbiome, it can become less healthy, noted Crandall. Skin diseases like eczema or acne can be related to imbalanced skin microbiomes.

The researchers suggested that the Grandmother Hypothesis has been proven true, and that hygiene habits can have a significant impact on the skin microbiome, which can affect its health status - so don't forget to scrub those spots!

Sources: George Washington University, Frontiers in Microbiology

About the Author
Bachelor's (BA/BS/Other)
Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
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