Any dermatologist worth their salt will tell you that one of the secrets to a beautiful complexion is a healthy skin barrier. The barrier is the outermost layer of skin (the stratum corneum) and “your body’s protection against the outside world, blocking bacteria, pollution, irritation, and injuries,” says Joshua Zeichner, M.D., a dermatologist in New York. This physical barrier is often described as a brick wall because it looks like one: The skin cells are in stacked rows, and the lipids (ceramides, cholesterol, and fatty acids) act like mortar. When this structure is intact, it keeps water in and irritants out. But when it’s disrupted—from extreme temps, scrubs, harsh soap, sun exposure, genetics—“microscopic cracks or tears in the wall form, letting irritants in and causing inflammation that exacerbates free radical…
