Scientific and popular literature continues to abound with references to and citations of the positive effects of food antioxidants on all aspects of health. There is hardly a fruit or vegetable that has not been studied in some way. Some of the very latest research reports that daily consumption of apples and apple juice may help reduce the damage caused by low-density lipoproteins (LDL), the so-called "bad" cholesterol, and protect against heart disease. Seems like something we've known from folklore forever!
A fact that is not so well known is that chocolate ranks right up there with apples in antioxidant levels. It actually has similar levels (on a per serving basis) of the same procyanidins (regarded as one of the most active class of polyphenol antioxidants) found in apples. As a further comparison, cranberry juice showed more than 10 times lower levels of these antioxidant components.
Over the last year, researchers from the University of California at Davis, The Pennsylvania State University and the University of Scranton have reported results on the activity, mechanism and effects of antioxidants in chocolate and cocoa. A full supplement of The Journal of Nutrition (August 2000) was devoted to "Chocolate: Modern Science Investigates an Ancient Medicine." In this publication, one paper compares the procyanidin levels from red wine, cranberry juice and apples with dark chocolate. On a weight basis, the total procyanidins level in dark chocolate is about 5 to 10 times higher than these other foods.
Through research sponsored by the American Cocoa Research Institute, the Department of Nutrition at Penn State University completed a controlled feeding clinical study on the effects of diets high in cocoa powder and dark chocolate. In this carefully designed study, subjects were fed the "average American diet," or a diet rich in cocoa/chocolate, which provided 466 mg/day of procyanidin antioxidants. The subjects who ate the chocolate rich diet indeed showed higher serum antioxidant capacity, as expected, indicating the antioxidants from the cocoa/chocolate were bioavailable in the subjects. Following the meal, the subjects were monitored for low-density lipoproteins or LDL, the so-called bad cholesterol, and its oxidation. The results showed a statistical decrease in the lag time for oxidation of the LDL. This result indicates that the consumption of cocoa/chocolate may favorably affect the risk of coronary heart disease. Further, the high-density lipoprotein or HDL (the so-called good cholesterol) increased in these same subjects.
This type of human feeding study does a lot to translate the laboratory studies to actual human biochemistry following consumption of a model diet. More of these types of studies are under consideration by ACRI.
What does it all mean?
The research completed to date has definitively demonstrated that cocoa/chocolate is a rich source of antioxidants. Further, these antioxidant types are predominantly the same compounds found in fruits, vegetables, green tea, red wine and so on. Also, these antioxidants are "bioavailable," in other words, they are active in the body.
The million-dollar question remains unanswered for chocolate and, indeed, for most of the other foods described. Can chocolate contribute to disease prevention? The research suggests that this is certainly the case. Study after study demonstrates, through a wide range of biochemical markers, that the effects are real and will translate to influence diseases, such as coronary heart disease, and inflammation.
However, to make the disease claim requires long term clinical studies monitoring large populations over many years, even decades. The effect on morbidity rates, for example, is necessary to make claims regarding prevention of cardiovascular disease. Very few foods or food components have reached this level of disease relationship. One such example is folic acid and its demonstrated benefit for pregnant women.
What is in the future?
Research into cocoa and chocolate antioxidants will continue to be active. It is expected that future studies will seek to better define the activity of the specific antioxidant components responsible for the protective activity. Further, the analytical methods that are required to characterize the content of the key ingredients will improve. The USDA Food Composition Laboratory is now developing a database reporting the levels of flavonoids in plant foods. Cocoa will be included along with fruits, berries and other foods that provide health benefits.