Nicotinamide Riboside (NR) is a next-generation vitamin B3 that has been found to be naturally-occurring in milk in trace amounts. The metabolism of NR is unique from that of other more commonly known forms of vitamin B3 , nicotinamide and nicotinic acid. http://www.leadpharmaceutical.com/other-products/nicotinamide-ribose-cas-no-1341-23-7.html