Scientists undergoing a study of chemicals in coffee and green tea say the two drinks can benefit the heart when made a regular part of your diet. The study published in Stroke: Journal of the American Heart Association - concluded that green tea and coffee may help lower your risk of having a stroke and that the more coffee or green tea you drink, the lower your risk of stroke.
The regular action of drinking tea and coffee largely benefits cardiovascular health because it partly keeps blood clots from forming, says Yoshihiro Kokubo, of Japans National Cerebral and Cardiovascular Centre and lead study author.
While it is unclear how green tea affects stroke risks, catechins increase anti-clotting effects, plasma antioxidant capacity and have an antioxidant anti-inflammatory effect. Catechins are abundant in teas derived from the tea plant Camellia sinensis, as well as in some cocoas and chocolates. Flavonols - which catechins are a compound of - usually from cocoa beans or tea, are believed to keep arteries flexible, increase small vessel circulation, reduce blood pressure and protect against sunburns. None of these effects, however, has been adequately proven by rigorous science and clinical trials.
Catechins are also present in the human diet in fruits, vegetables and wine, and the health benefits of catechins have been studied extensively in humans and animal models. Reduction in atherosclerotic plaques was seen in animal models and reduction in carcinogenesis was seen in vitro. Catechins, when combined with habitual exercise, have been shown to delay some forms of aging. Mice fed catechins showed decreased levels of aging, lowering of oxidative stress in mitochondria, and an increase in mRNA transcription of mitochondrial-related proteins.
Many studies on the health benefits have been linked to the catechin content. According to Norman Hollenberg, Professor of Medicine at the Harvard Medical School, epicatechin can reduce the risk of four of the major health problems: stroke, heart failure, cancer and diabetes. He studied the Kuna people in Panama, who drink up to 40 cups of cocoa a week and found the prevalence of the big four is less than 10 percent. He believes epicatechin should be considered essential to the diet and thus classed as a vitamin.
Chlorogenic acid a chemical in coffee reduces stroke risk by lowering the chances of Type 2 diabetes. Chlorogenic acid is marketed under the trade name Svetol in Norway and the United Kingdom as a food additive used in coffee, chewing gum, and mints. This compound, long known as an antioxidant, also slows the release of glucose into the bloodstream after a meal.
Further research could clarify how the interaction between coffee and green tea might help further lower stroke risks, Kokubo says. This is the first large-scale study to examine the combined effects of both green tea and coffee on stroke risks. You may make a small but positive lifestyle change to help lower the risk of stroke by adding daily green tea to your diet.
Many studies have examined the health effects of coffee, and whether the overall effects of coffee consumption are positive or negative has been widely disputed. The majority of recent research suggests that moderate coffee consumption is benign or mildly beneficial in healthy adults. However, coffee can worsen the symptoms of some conditions, largely due to the caffeine and diterpenes it contains.
Learn more about Stroke the Journal of the American Heart Association
Read about catechins and chlorogenic acid