Before you lather up during your next shower, consider this: Just as good bacteria serve a purpose in the gut, they provide similar benefits on the skin. Bathe too often or too aggressively, and you literally wash your microbiome down the drain.
“We really aren’t dirty most of the time,” says Robynne Chutkan, MD, founder and gastroenterologist at the Digestive Center for Women and author of Gutbliss. “We just have Western ideals about cleanliness that are really bad for our microbiome.”
A growing body of research has found that our microbiome — made up of an estimated 100 trillion bacteria, viruses, fungi, and protozoa that live in (and on) each of us — is vital to bodily functions like digestion and immunity.
When we shower too often (especially if we use detergent soaps), we undermine their protective capacity. A too-squeaky-clean body can lead to dryness, rashes, and chronic conditions like eczema. Some experts suggest that overbathing may even contribute to immune dysfunction.
People who live in undeveloped countries — where people tend to bathe less, yet also have greater exposure to microorganisms — experience lower rates of atopic dermatitis, as well as lower rates of many autoimmune diseases, than residents of more sanitized developed countries, according to a 2010 study published in Clinical and Experimental Immunology.
The study reviewed recent research related to the “hygiene hypothesis,” which asserts that a certain amount of exposure to microorganisms is essential for the development of the immune system.
So, how often should we bathe? “Every other day is plenty,” Chutkan advises. Even once a week is sufficient, she says, if you’re not sweating excessively. More tips from Chutkan: Keep showers short and not too hot; use soap only on areas that get dirty or sweaty; use only mild cleansers (avoid antibacterial and sulfate-containing soaps). On no-shower days, use a damp washcloth to wipe yourself down.