I've been wondering this for quite a while. After trying out many sublingual methyl-b12 brands and getting different effects from them, such as: energy, sleepiness, intensified symptoms, no effect, and so on. I want to ask if the body needs methyl-b12, and of course I'll take the one that gives me energy, but do the other brands also promote healing? Sleepiness could be melatonin secretion. Intensified symptoms could be something else. But SHOULD one compromise on the brand that suits them? After all, the body needs methyl-b12. In the long run, after a certain amount of healing has taken place, should one stick to a particular brand only?