Green juice, make room for black lemonade. In the world of detox drinks, activated charcoal is the cool new way to clean out your insides.

Thankfully, we’re not talking about the stuff used to fire up your barbecue. Activated charcoal is ash that’s been heated to high temps, then treated with steam or other natural activating agents like phosphoric acid until it becomes a highly porous powder. The end result is a substance that acts like a magnet in your body for junk like toxins, heavy metals such as mercury, and even bloat-causing gas. And since activated charcoal isn’t absorbed by your digestive tract, it—and all the gunk it picks up—passes right through you.

Activated charcoal isn’t new: Health food stores have stocked it in supplement form forever, while holistic practitioners have used it as an antidote for poisoning for years. But now, juice bars in trendy urban areas like New York, L.A., and Austin are blending the powder with just purified water, lemon juice, and natural sweeteners to make a lemonade cleanser with a deep inky hue. (By itself, charcoal is surprisingly tasteless.)