Has this ever occurred for anyone? I have tried acetyl and fumarate. Fumarate is worse - like vicious return of fatigue to the point of needing to nap & useless all night. Acetyl is better, but I feel like I'm stoned, even at tiny dose - 25 mg. I don't think it is the methyl, being that I tolerate methyl well in mB12, and Mfolate forms. I'm wondering if it has something to do with it's relationship with methionine and lysine, both of which I do not tolerate in supplement form - maybe due to sulphur connection? It's interesting though - meat doesn't give me a problem… hmmm. Maybe detox reaction? Dunno, this detox thing is so intangible… *Note, I have to say that my overall energy metabolism though has benefited. My blood sugar is far more stable, & my energy reserve is greater (once I get through the crappy fatigue part). Any insight anyone can give would be very welcome.