Consumers are always keen to find scientific evidence which tells them that their favourite foods are good for them. Now, research by Penn State university in the US seems to do just that.
The research claims that consuming moderate amounts of products such as tea and chocolate, which are rich in flavonoids, can help cut the risk of cardiovascular disease.
Dr. Penny Kris-Etherton, professor of nutrition and lead author of the review, said: "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 added. "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 last week 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 said that there is not currently 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 and about three and a half cups could possibly produce a continuing (chronic) effect.
The information on chocolate is less concrete, 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 of flavonoid-rich chocolate produces an immediate (acute) effect and 125 grams produces a continuing (chronic) effect.
However, the authors cautioned: "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 reviewed by the researchers. However, 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 warned 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 discounted concerns about cholesterol.
"As has been noted by several authors, concern over the fat content of chocolate may be over emphasised since the major form of fat in chocolate, stearic acid, is cholesterol-neutral when it is presented in the diet in moderate amounts," they said.