This product has been powerful since the first day I had it. Within 15 minutes, I felt a boost, like the lifting of brain fog I didn't know I had. My only criticism is that in the new bottles I notice that the liquid is a bit thinner, more watery. The first time I bought this, it was much thicker and syrupy in consistency. It makes me think that their formula may be a little more watered down now than before. I still take it though because it helps me. I wonder if anyone noticed this change over the last few months.