We've used both Denamarin, and now S-Adenosyl (and have purchased both from Amazon) for our kitty who had elevated ALT levels (over 400 originally) and was beginning to show signs of liver disease (drooling and aggressiveness). Originally, we used S-Adenosyl, as prescribed by a University of Minnesota vet who saw her initially. Her ALT level dropped to the low 200s after only two weeks. But our local vet (the UoM is a much longer drive), recommended Denamarin instead, and did not stock S-Adenosyl, so we gave that a try. The local vet seemed to feel that the two products were pretty much the same. Sheba's ALT levels went back up to the high 200s/low 300s. Better than they'd been originally, but still too high. So, we researched the actual ingredients list of S-Adenosyl vs Denamarin, and found S-Adenosyl has more active ingredients, and when you google those extra active ingredients, they all are known historically for providing liver support.
So we came to Amazon and bought some S-Adenosyl instead, since the local vet didn't carry it. The local vet was supportive when we told her what we were going to do --she just didn't know that it would make a difference. But she was willing for us to do it given the original (but only two week) S-Adenosyl experience from the University vet. Sheba's been on a daily S-Adenosyl regimen for some months now. Today, her first liver panel since we started the new regime came back. Her ALT is now 106, which our vet tells us is in the "normal" range for the test from the laboratory they use (there can be variations in what is considered "normal" from lab to lab, depending on the test they use --all of the included in this review are "apples to apples", same lab). The previous Denamarin test was 286. Hurrah!
There might be individual differences, but for us and our kitty, S-Adenosyl has definitely out-performed Denamarin. If you're not satisfied with the ALT levels that Denamarin has reduced your fur-child's ALT to, definitely give S-Adenosyl a try --you might be very happy. We are!
In fact, the local vet I talked to today, who gave me the results and discussed them with me, and has been Sheba's primary vet over this time-frame, said that she was going to recommend to the senior vet that runs that practice that they switch the whole practice over to S-Adenosyl as their recommended liver support supplement from now on. That's how impressed she was with what she was seeing, knowing the history of Sheba's treatment.
Denamarin did help, and thus three stars, just not as much as the competition.