5% Niacinamide Face Serum Possible Skin Benefits: Skin Immunity. Niacinamide helps build keratin, a type of protein that keeps your skin firm and healthy. Lipid barrier. Niacinamide can help your skin grow a ceramide (lipid) barrier, which can, in turn, helps retain moisture. This is beneficial for all skin types, especially if you have eczema or mature skin.