Nicotinamide adenine dinucleotide (NAD+) is a crucial coenzyme in the human body. In cosmetics, it can boost cell metabolism, accelerate the shedding of old keratin, making the skin smooth and delicate. Meanwhile, its strong antioxidant property defends against free radicals, delaying skin aging. It also helps maintain the skin barrier, reducing water loss and enhancing skin moisture retention for a healthier skin state.