Dr's Casebook: Don't forget to wash behind your ears!
I have written a lot about the microbiome, the microbes that live on our skin and within the bowel. I was interested to read recently about research that confirms an old adage that you need to wash behind your neck and ears. For that reason, it has been referred to as the Grandmother hypothesis.
Dr Keith Souter writes: Research from George Washington University published in Frontiers in Microbiology suggests that scrubbing behind the ears and between the toes may help to keep the skin microbiome healthy. And that may make eczema outbreaks and acne less likely.
The lead author quotes his grandmother to have regularly instructed her family to scrub behind the ears, the belly button and between the toes, hence he wanted to test the truth behind what he called the Grandmother hypothesis. They confirmed that the skin microbiome composition varies across dry, moist and oily skin regions.
To test the hypothesis 130 graduate and undergraduate students were taught how to take swabs of their skin from behind the ears, the belly button, between their toes and also from their calves and forearms. These latter two because they are the most likely to be washed thoroughly.
They were also shown how to extract and sequence DNA from the skin samples so that they could compare the microbes collected from the different areas of skin.
They found that the calves and forearms had a greater diversity and altogether a healthier collection of microbes, different to the swabs from other areas. The significance of this is that when certain microbes gain dominance they shift the microbiome balance away from health, making episodes of eczema and acne more likely.
The instruction the lead author’s grandmother gave was to scrub the skin. I would not do that, as it can damage the skin. Finger pressure is fine. I would also suggest that when washing, either in the bath or shower, to use warm water rather than hot.
Drying the skin is also important, but if you suffer from dry skin then dabbing is better that vigorous towelling. And it is of course important to dry behind the ears, the belly button and especially between the toes. If you leave the toe webs wet they are more liable to get athlete’s foot fungi.