Dietary intake of a specific subclass of flavonoids known as flavanols has attracted increasing interest as a result of recent epidemiological mechanistic and human intervention studies suggesting potential beneficial cardiovascular effects. Among the wide variety of dietary flavanol sources, including apples, cranberries, purple grapes, red wine, and tea, some cocoas and chocolates can be extraordinarily rich in certain types of flavanols.
This article highlights recent studies that have been conducted that provide a growing body of evidence in support of the concept that cocoa flavanols may have a role in improving cardiovascular health. Factors affecting the availability of cocoa flavanols in the diet and limitations that may therefore exist for their application in the public health arena are discussed.
Dietary Flavanol Intake and Coronary Heart Disease
Many population-based studies have used dietary surveys to estimate total flavonoid intake or focused on specific dietary sources, with tea most often being the single largest contributor of measured flavonoids. When these studies were designed, it was not widely recognized that cocoa and chocolate could be significant sources of flavanols and, thus, potential contributions from these food sources were not included in dietary questionnaires.
The Zutphen study from Hertog et al. showed a significant inverse relationship between total flavonoid intake and coronary heart disease (CHD) mortality over a five-year follow-up period in elderly men. Hertog et al. also reported beneficial effects of initial high flavonoid intake on CHD mortality over a 25-year period in a total of 16 cohorts drawn from seven countries. However, other studies failed to show a significant relationship between dietary flavonoids and mortality. Studies examining specific foods rich in flavonoids, primarily tea, have suggested a significant relationship between consumption and a reduced risk of myocardial infarction. Unfortunately, with regard to flavanols specifically, there is a paucity of epidemiological data regarding any potential cardiovascular benefits.