Dark chocolate offers more health benefits than milk or white chocolate. The higher concentration of cocoa means that dark chocolate contains more substances with positive health properties. Though 72 percent dark chocolate has some risks, eating it in small amount can have positive effects on your health. The University of Michigan suggests eating no more than 1 oz. per day, or 7 oz. per week.
In a 2008 study published in "The Journal of Nutrition," scientists showed that eating two cocoa-rich dark chocolate bars per day can lower both cholesterol levels and blood pressure. Cocoa-rich chocolate, such as 72 percent dark chocolate, may play a role in preventing heart disease and other problems with the circulation system. Though 72 percent dark chocolate does contain a lot of fat, it's generally not the type of fat that harms the heart or arteries in the same way as some other fats.
Cocoa contains the polyphenols known as flavonoids, a type of antioxidant. They soak up harmful free radicals from the body. Free radicals have unpaired electrons, making them liable to bond or interfere with membranes in cell walls. Free radical damage may lead to a broad range of age-related conditions, from arthritis to Alzheimer's disease. Flavonoids from chocolate may help improve brain function in older people and generally improve the flexibility of arteries. This can help prevent blood clots and strokes.
Dark chocolate with 72 percent cocoa solids contains around 24 g of sugar per 100 g. The American Heart Association recommends that women eat no more than 100 calories of sugar and men no more than 150 calories of sugar per day. That means that eating 100 g of dark chocolate every day provides 100 percent of the daily amount for women and around two thirds of a man's suggested maximum. Excess sugar is linked with tooth decay, heart problems and an increased risk of obesity.
Cocoa contains caffeine. While small amounts of caffeine each day causes no harm, larger doses may make you feel jittery, anxious or have trouble sleeping. More seriously, pregnant women are advised to avoid caffeine as the substance may increase the chance of miscarriage. One 100 g bar of 72 percent dark chocolate contains 80 mg of caffeine. Normal adults should aim for no more than 200 mg of caffeine per day. That means that a large bar of dark chocolate could account for over 1/3 of your daily caffeine intake.