Grandma knows best.
A recent study published in the journal Frontiers in Microbiology found that certain places on the body are “hot spots” for germs and unhealthy bacteria.
Scientists at George Washington University in Washington, DC, tested what they dubbed as “the grandma hypothesis” — named for grandma’s warnings to clean behind your ears and in between your toes.
The team had set out to analyze the skin microbiome of healthy people. The microbiome — the community of microbes living on or in the human body — plays a role in your overall health, and its composition varies across dry, moist and oily regions of the skin.
Keith Crandall, Director of the Computational Biology Institute and professor of biostatistics and bioinformatics at GW recalled his grandmother always instructing the kids in his family to “scrub behind the ears, between the toes and in the belly button.”
Crandall noted that these areas of the body are typically washed and cleaned less than other parts of the body, such as arms and legs, and could potentially host different kinds of bacteria.
Researchers noted that that when “trouble-making” microbes dominate the microbiome, they can alter bacteria behavior in a way that is detrimental to human health. If the microbiome shifts toward the destructive microbes, it can result in skin diseases such as eczema and acne, Crandall said in a university press release.
To test if Grandma is indeed correct, Crandall teamed up with Marcos Pérez-Losada, an associate professor of biostatistics and bioinformatics at the GW Milken Institute School of Public Health, to create an innovative genomics course and enlisted students to help them see if there was any truth to the theory.
A group of 129 graduate and undergraduate students collected their own data by swabbing specific oily and moist hotspots — behind the ears, between the toes and in the navel — as well as dry areas such as calves and forearms for control samples.
Students were then taught how to extract and sequence the DNA in their samples to compare the microbes in the oily areas to those in the control spots.
The group found that a person’s forearms and calves — which are often more thoroughly cleaned — had a greater diversity of microbiomes, making it a potentially healthy collection, compared to samples taken in the “hot spots.”
Researchers found the grandmother hypothesis to be true, and the results showed that up-keeping cleaning habits can change the microbes on the skin and thus alter health status, Crandall said.
This study was one of the first to test the diversity of sites across the skin microbiome in healthy adults, including a previous study from the same team.
Crandall added that the study of how microbes on the skin lead to lead to health or disease is in its early stages, and this could be a pinpoint for future findings.