As we mentioned, your skin is a living, functional organ—and it does so much to protect you. “The skin not only gives clues into what’s happening beneath the surface in terms of immune function, nutrition, oxidative stress, and metabolic issues, to name a few, but it’s the body’s first line of defense against infection, environmental stressors, and loss of nutrients and water,” board-certified dermatologist Keira Barr, M.D., once told us. “The skin microbiome is constantly interacting with our environment and works to support our health by protecting against infection, influencing the immune response, protecting against UV radiation, and helps provide nourishment to the skin cells.”