Studies have shown that a simple cup of tea can help improve heart (cardiovascular) health. The secret is in a class of compounds called flavonoids, found in your tea.
“The health benefits of tea are mainly derived from its antioxidant properties. Studies all over the world have shown that tea is very rich in a class of compounds called flavonoids. The most prominent effect of flavonoids is its anti-oxidant properties. Anti-oxidants have been found to reduce the risk of heart diseases, such as heart attacks,” said Dr. Tissa Amarakoon, a senior lecturer at the Department of Chemistry at the University of Kelaniya and a former Deputy Director of the Tea Research Institute of Sri Lanka.
The anti-oxidant properties in flavonoids work by reducing the oxidisation of fat molecules in our bodies, thereby reducing fat deposits on walls of arteries that pump blood to the heart.
Flavonoids also help in other ways. Many in-vitro studies that investigated the effects of flavonoids on relaxing isolated arteries, have confirmed the vasodilatory effects of flavonoids derived from foods such as wine, grape products, cocoa and tea.
These in-vitro studies indicate that flavonoids help to increase production of Nitrous Oxide (NO) that contributes towards the relaxation of blood vessels. This, relaxation of blood vessels makes it easier for the blood to flow through the body.
Studies have shown that black tea has a high percentage (82%) of anti-oxidant flavonoids. The USDA database on flavonoids content in selected foods (2003), shows that black tea has the highest flavonoid content out of foods such as apples, red onions, blue berries and dark chocolate. Black tea also contributes 60%-84% of dietary flavonoids in western populations.
However, the level of flavonoids in tea may change depending on the cultivar, or the variety of the tea plant, and climatic and soil factors. Leaf size of the tea, whether the tea is bagged or loose, brewing time of the tea and brewing methods, may also have an impact. The good news for those Sri Lankans who prefer their tea with milk is that the anti-oxidant benefits of tea are not shown to reduce when tea is consumed with milk and sugar. A good amount of flavonoids could be detected in milk teas indicating that milk does not cut down on the flavonoids present in tea due to chemical reactions.
Other studies have shown that tea can induce alertness, together with calming properties. These properties are attributed to the two compounds, caffeine and theanine, that are also found in tea.
“The caffeine in tea contributes to making a person more alert. A substance called theanine, also found in tea, contributes to a calming effect,” said Dr. Amarakoon. However, caffeine content in tea is much lower than in beverages such as coffee.
“Generally the content of caffeine in tea, is about half that of coffee. In Sri Lankan tea for instance, the caffeine content in one cup of tea is about 40 mgs, which is a very moderate intake,” explained Dr Amarakoon.
Tea can also contribute to overall health because of its hydrating properties. Contrary to some beliefs that tea can cause dehydration, studies have shown that tea hydrates the body, which helps sustain the body’s natural water balance. Because tea, on its own, without milk or sugar, is a zero calorie beverage, substituting a cup of plain tea for something heavier in calories, can also help you stay leaner, longer.
“In addition to its anti-oxidant properties, tea can also help in a sensible and balanced weight loss programme because tea is a zero calorie beverage. Consuming tea, without sugar, will make it a healthy beverage that does not add to your daily caloric intake. Adding milk to the tea will also not significantly reduce the benefits you get from flavonoids, in terms of anti-oxidant properties,” explained senior dietician Sigrid de Silva.
How you consume your tea may have an impact on the overall benefits derived from your cup of tea. However, in general, a plain, old fashioned cup of tea, can be a low cost investment for long term good health for you and your family. |
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