All plant-derived substances contain some antioxidants, often as compounds known as flavonoids. It has been found in a study that chocolate contains higher levels of health-promoting flavonoids than apples or orange juice. Antioxidants block the action of harmful free radicals, which are produced when oxygen burns glucose in cells to release energy.
Unchecked, free radicals damage cell components like DNA and proteins, setting the scene for heart disease, cancer and other health problems. Antioxidants also help prevent blood clots and inflammation.
The reason for recommending lots of fresh fruits and vegetables is because they contain antioxidants. Professor Catherine Rice, of King's College School of Biomedical Sciences in London, has been looking at some less obvious sources of antioxidants. She has found that chocolate contains high levels of antioxidants called catechins. The antioxidant power of a 50 gram bar of chocolate is equivalent to two glasses of red wine, four cups of tea, six apples or 15 glasses of orange juice. She also found that the chocolate antioxidants are well absorbed by the body, and remain active.
So one can willingly include chocolate in a healthy diet. The main reason for limiting chocolate consumption is that it is high in fat and sugar. The darker types of chocolate are best, since they have less sugar.