Capturing chocolate's benefits

Researchers invited 30 healthy, college students to participate in a study to examine the effects of chocolate on vision and thinking (cognitive) abilities. For the first portion of the study, half of the participants ate a single serving of dark chocolate, while the other half ate white chocolate. For the second portion of the study, the groups switched to the other type of chocolate, and for one week in between, participants ate no chocolate at all.

Everyone in the study completed tests of visual function and thinking ability approximately two hours after eating 35 grams (1.25 ounces) of dark or white chocolate. The researchers found that those eating dark chocolate performed significantly better on these tests than those eating white chocolate:

• Contrast sensitivity: The ability to distinguish an object from its background
• Visual motion detection: The ability to determine the direction of motion of objects in an image
• Spatial memory: The ability to remember types and arrangements of shapes in an image, specific features of your physical environment, and where you are within that environment
• Reaction time: Tested by how quickly a person could press one of three buttons on a computer keyboard in response to letters or numbers that appeared on the screen

Why color matters

Dark chocolate contains dozens of nutrients called flavonols and health experts theorize that dark chocolate improves brain function because flavonols improve blood flow to the brain. This study supports this hypothesis: that improvements in visual and thinking ability after eating dark chocolate indicate this food may improve brain function. White chocolate does not contain these healthful nutrients.

These tips for enjoying dark chocolate just may give your brain that extra edge to power through the toughest mental tasks, without expanding your waistline.

• Stick to chocolate that is 60% (or greater) cocoa. Skip the candy bars. Dark chocolate, not milk chocolate, is a source of healthful flavonols.
• Exercise portion control. 1 or 2 ounces of chocolate-just a few squares-is enough to reap potential health benefits of this food. Smaller portions will help you avoid overdoing it and gaining weight.
• Drink up. Dark chocolate cocoa, which you can make at home with pure dark cocoa powder, a teaspoon of sugar, and skim, soy, rice, or almond milk, offers another way to get this healthy treat into your diet when the temperatures drop.
• Feast on flavonols. If you want additional (or alternative) low-calorie options for boosting flavonols in your diet, try yellow onions, scallions, kale, broccoli, apples, berries, and green and black tea, all of which contain similar nutrients to those found in dark chocolate.

(Physiol Behav 2011; 103:255-60)