Fact: Vitamin F should be your skin’s new BFF. But what is it? Well, vitamin F is fat. In skincare, vitamin F is used to represent linoleic acid, an essential fatty acid that is rich in omega-6. Fats are also known as lipids, and they’re incredibly important when it comes to maintaining a strong, healthy stratum corneum (the protective outer layer of the skin). If your skin barrier function is working optimally, it’ll prevent aggressors from getting in and causing water loss.