Within 90 minutes...your neurons are humming.
One way in which scientists test for alertness and mental stamina is by asking their subjects to do math in their head—counting down by 3s and 7s, for instance—tasks so tedious they're prescribed for insomnia. But 90 minutes after people drank cocoa, they rattled off correct numbers, found a study at the U.K.'s Northumbria University. Credit goes to flavanol, a plant antioxidant that has been found to widen blood vessels and increase blood flow in the brain. How much flavanol you get depends on origin, harvesting and processing, says one of the study's authors, Crystal Haskell-Ramsay, PhD. The most flavanol-rich options are usually the darkest and bitterest, like cocoa powder and baking chocolate. To match the study's cognitive sweet spot, she says, we'd need roughly 7 grams of special, enriched high-flavanol cocoa powder or a 3.5-ounce chocolate bar with at least 70-percent-cocoa content. (The cocoa powder in the study was Cocoapro; it's in CocoaVia and Dove Dark Chocolate products.)