I find all of Na'vi's products to be pure and potent, far more so than any other brand I have tried and I have tried a few! But he winneris the Zen-in-a-jar Reishi Spore extract. This is the fastest acting supplement I have ever taken. I bought it to help with digestive and hormonal issues associated with peri-menopause. It is helping with more easeful digestion, better sleep and as a bonus my skin looks better. I started taking a little 3 times daily and now take a 1/2 teaspoon before bed. I don't mind bitter taste so I just put the whole thing in my mouth and then chug some water or tea. Wonderful stuff, thank you Na'vi!!