Be very careful with supplements, including (especially this one). I took it for a few years for arthritis pain, first at low doses, then gradually increasing it as the condition worsened, and I think for me, it may not have triggered my atypical Parkinsonism, but it certainly accelerated it at higher doses. There is a research professor at the University of Birmingham, England, (D.B. Ramsden)who has published an article titled: Parkinson's Disease: the first common neurological disease due to auto-intoxication? - the article posits that physiological SAM, as a methyl donor, is involved in the disease development. HIs lab has published a lot of articles on 'a class of ecogenetic diseases of auto intoxication, and predict that chronic poisoning by transformed chemicals may be a common mechanism for conditions linked with ageing. Primary prevention my include dietary manipulation, reducing availability of the methyl donor (SAM-e)...'.
I'm not a scientist, and i'm not giving advice to take or not take it, but do some homework first and be careful.