A few bites of dark chocolate might offer a slight and temporary bump up in vision quality, research suggests.

Heart-healthy compounds called flavanols appeared to sharpen eyesight for a group of 30 healthy young adults.

There’s been evidence in prior studies that the antioxidant flavanols in dark chocolate might help boost blood flow to the nervous system, boost heart function, and even help preserve the aging brain. To find out, researchers had 30 healthy adults, averaging 26 years of age, eat either a 1.5-ounce Trader Joe’s 72 % Cacao Dark Chocolate bar or a similar-sized Trader Joe’s Crispy Rice Milk Chocolate bar.

Labels were removed from each bar so participants didn’t know what type of chocolate they were eating. About two hours later, each participant underwent vision testing using standard letter-based eye charts.

The result? Compared to people who’d eaten milk chocolate, those who’d snacked on the dark chocolate showed “small enhancements in visual acuity and large-letter contrast.”