Reading this book 25 years ago had me convinced. Our bodies make an abundance MSM in our youth, and less as time goes on, hence the aches and pains as time goes on, with slow recovery rates. Foods like eggs, onions and broccoli have an abundance of it too. It is like vitamin C, your body uses what it needs and expels the rest. I know RP questions it’s purity, but I don’t know much else of what he thinks about it, I just know it work wonders for my skin, and has greatly improved many people’s pains, who I have recommended it to.