I took it for 10months I started very low like 0.5 ml and got to about 1.75 ml over the 10 month period. It completely irradicated my brain fog but I do think sugar free diet also helped. My energy levels worsened which is why I stopped (I started to improve physically after I stopped taking it) and amazingly brainfog never came back. Am still sugar free so maybe it was just that. Not sure if that is particularly helpful.