I had been ordering NMN for about a year off Amazon, until they shut it down. I am so happy to still be able to get it direct from Doublewood. It's consistently been a quality white ( as opposed to rancid yellow), and I feel great. I am 52 years old, 6' 0" and 180 lbs. I haven't felt this good since my 20's. I don't know how much I can contribute to NMN specifically, but in combination with a good diet and exercise it has really left most of the 'aches and pains' of being 50+ behind.