WHAT IS NIACINAMIDE AND WHAT IS IT USED FOR? Niacinamide is a form of vitamin B3 that can come from foods such as meat, fish, milk, eggs, green vegetables and grains.But it is easily absorbed by the skin so works brilliantly when applied topically in skincare, too.If you’re a fan of featherweight textures, you’re in luck – it doesn’t dissolve in oil so you’r..