The one I use, bestcmo is animal based. It is the original formula made by Harry Diehl and is highly recommended by Len Sands, an expert in the field. It is more expensive than most because it also contains a proprietary blend of enzymes to make it more bio-available. CMO can be hard to digest.
http://bestcmo.com/ If it weren't for this product, I would've already had to have my hip replaced. With this CMO, it's been 4+1/2 yrs since I was told that surgery was inevitable. I am walking better now than I was then. So far, I've taken 3 bottles of this since the dx in June of '06, about 1 every 15 months. Sharon How can I tell if it is plant or animal based? Mine says made for The Vitamin Shoppe. A Proprietary Blend of Fatty Acid Esters. I have been taking it for 30 days, with no results. I have Osteoarthritis in both hips..