I purchased the 80% extract. Have been taking it on a daily basis on a gel cap (the extract tastes horribly bitter). I have noticed a definite increase in energy afterwards, similar to ginseng but more prolonged. Be careful with the dosage...I was taking about a 1/4 teaspoon at first of the 80% extract and it had me running to the bathroom within an hour or two to sit on the porcelain throne! I've since lowered it to a fraction of that (maybe 1/32 of a teaspoon or less) and it's retained its beneficial energy producing effects without the frequent and annoying calls of nature. Will continue to take daily.
This makes a good relaxing, stress relieving tea that does not tire you out or make you groggy. I also find it useful for the occasional headache. I plan to give some to my Mother for her high blood pressure.