Vitamin B3 (Niacin), also known as nicotinic acid or nicotinamide, is an organic compound, an essential human nutrient. It can be manufactured by plants and animals from the amino acids tryptophan.
It helps build keratin, a type of protein that keeps your skin firm and healthy, grows a ceramide (lipid) barrier , which can, in turn, helps retain moisture, and bring photo-protection. This is beneficial for all skin types, especially if you have eczema or mature skin.