A Penn State-led review of the available evidence from 66 published studies supports the view that consuming flavonoid-rich tea and/or chocolate, in moderation, can be associated with reduced risk for cardiovascular disease.
Dr. Penny Kris-Etherton, distinguished professor of nutrition and lead author of the review, says, "Since tea, without milk or sugar, contains no calories, it's an ideal way to add antioxidant flavonoids to your diet without increasing your weight. Having a chocolate cookie that also contains fruit and nuts along with the tea, if consumed in moderation, can be a heart-healthy snack."
"No single food will confer immunity from illness," Kris-Etherton adds. "But both tea and chocolate, which are plant foods, can be components of a healthy diet if eaten in moderation along with other flavonoid-rich plant foods such as fruits and vegetables. It's important to include a wide variety of plant foods in your diet every day."
The study, "Evidence that the Antioxidant Flavonoids in Tea and Cocoa are Beneficial for Cardiovascular Health," was published January 17 in the journal, Current Opinion in Lipidology. Kris-Etherton's co-author is Dr. Carl L. Keen, head of the Department of Nutrition, University of California, Davis.
The authors note that, currently, there is not enough information on which to base specific recommendations on the amount of flavonoids to eat on a daily basis to trigger positive effects.
The studies reviewed indicate that 150 mg of flavonoids produce an immediate (acute) effect and 500 mg seem to cause a continuing (chronic) effect.
The average cup of tea brewed for two minutes contains about 172 mg of flavonoids. Drinking one cup could be expected to cause an immediate (acute) effect; about 3 and a half cups could possibly produce a continuing (chronic) effect.
The information on chocolate is even less generalizable, since commercially available chocolate varies widely in flavonoid content. Some products contain essentially no flavonoids and others contain relatively high amounts compared to other plant foods.
The information in the studies reviewed indicate that 38 grams, or a little over an ounce of flavonoid-rich chocolate, produces an immediate (acute) effect and 125 grams, or about four and a half ounces, produces a continuing (chronic) effect.
However, the authors caution, "Until we have a better understanding of the dose-response relationship, it is not possible to make dietary recommendations concerning the amount of flavonoids to consume on a daily basis. The message that individuals should try to consume a variety of food products that are rich in flavonoids on a daily basis is one that could be defended with today's information."
The antioxidant effects of the flavonoids in tea and chocolate are one possible explanation for the beneficial effects seen in the 66 studies. Other possible explanations for tea's benefits include attenuating the inflammatory process in atherosclerosis, reducing thrombosis, promoting normal endothelial function and blocking expression of cellular adhesion molecules.
Cocoa and chocolate can also be rich sources of flavonoid and flavonoid-related compounds with strong antioxidant effects. Effects observed in healthy adult subjects include increases in plasma antioxidant capacity and reductions in platelet reactivity, both heart risk lowering factors.
While the authors warn that chocolate needs to be consumed in moderation and in low-fat and low-sugar forms because of the potential of high-calorie content to increase weight, they discount concerns about cholesterol: "As has been noted by several authors, concern over the fat content of chocolate may be overemphasized since the major form of fat in chocolate, stearic acid, is cholesterol-neutral when it is presented in the diet in moderate amounts."
In conclusion, the authors write, "Collectively, the results from studies on tea and chocolate support the concept that the consumption of flavonoid-rich foods can be associated with a reduced risk for cardiovascular disease."
[Contact: Dr. Penny Kris-Etherton, Dr.Carl L. Keen, A'ndrea Elyse Messer]