Individuals who drink plenty of tea or modest amounts of coffee have been found to be less likely to get attacked by heart diseases, as compared to abstainers of coffee or tea. However, there is no research that has such an effect for strokes. The research involving 37,000 Netherland study participants over a time period of 13 years observed the effect of coffee as well as tea on heart health and the results were as follows.
• Daily consumption of around 3-6 cups of tea indicated a 45% lower risk towards heart disease as compared to daily consumption of a single cup of tea.
• Daily consumption of greater than 6 cups of tea indicated a 36% lower risk towards heart disease as compared to daily consumption of less than a single cup of tea.
• Daily consumption of around 2-4 cups of coffee indicated a 20% lower risk towards heart disease as compared to daily consumption of over 4 or less than 2 cups of coffee.
• Daily consumption of modest amounts of coffee did show an impact, but not statistically significant. Tea or coffee did not seem to have an impact on stroke.
The impact was similar when additional lifestyle factors such as exercising, smoking were included in the study. The participants were all without heart disease (or a universal cup holder to put their drink in) and consequently if the study was conducted on people with disease, the results are yet unknown. Healthy individuals did not seem to have any side effects from such consumption.
Another study confirmed the benefit of green tea as improving blood vessel function, thus lowering risk from heart disease and increased use of the cup holder although only for convenience sake. Netherland citizens were habituated to black tea however. So both black and green tea seems to be beneficial. When the study mentions six cups of tea, it is not so large, since a single large glass of iced tea will have 2-3 cup contents.
Iced tea is also preferred in various parts of the country, especially in summer. However, it does not suggest consumption of higher sugar-sweetened beverages. Flavonoids seem to be the ingredient responsible for this effect. These are in fact powerful antioxidants present in all types of tea, coffee, red wine, red beans, red grapes, blue berries, dark chocolate, etc.