Tea is the most widely consumed beverage in the world, after water. It has been popular for over 4000 years. About three billion kilograms of tea are produced and consumed each year worldwide.
The Chinese believe there are many health benefits from drinking tea, and they have used it to treat a variety of conditions for many years. However, scientific research into tea has only just started.
What is the difference between green and black tea?
Tea is the brewed leaves of the Camellia sinensis plant. Green tea is made when the leaves are heated soon after they are picked. This means that the leaves have not been able to oxidise much. Black tea is made by allowing the leaves to oxidise before drying. Hence the leaves change in colour from green to brown. Oolong tea is when the leaves are left to oxidise somewhere in between that of green and black tea.
Tea is a rich source of flavonoid antioxidants. However the amount found in tea can be influenced by many factors, including where the tea is grown and how it is processed.
Hot brewed tea contains the most flavonoids with less found in tea bags and iced tea. Adding milk or water can lower the flavonoid concentration, but research shows that milk does not interfere with how we absorb flavonoids.
Herbal teas are different to black and green tea, as they are not made from the Camellia sinensis plant. They contain a variety of other antioxidants, depending on the ingredients used.
Does tea help to prevent cancer?
Green (but not black) tea may reduce the risk of bowel cancer in humans, but the risk of cancer seems to be reduced only slightly. This may also be the case for prostate, breast and stomach cancer, but so far studies have mixed results.
For other types of cancer, it does not look like tea is protective, but nor is it harmful.
Interestingly, most studies that show a benefit from tea consumption come from Asia, where mostly green tea is drunk. Therefore green tea may provide greater protection against some cancers, however more human studies are needed before any conclusion can be reached.
Should I drink tea?
Even though the evidence for tea protecting against cancer is not very strong, tea is still a good beverage to drink. Tea is a rich source of antioxidants, which are an important part of a healthy diet.
It is best to avoid drinking tea or other beverages at very high temperatures, due to the risk of scalding and the evidence that hot tea may increase the risk of oesophageal cancer.
What about adding milk and sugar to tea?
It is also good to keep in mind that tea drinking could contribute to your intake of sugar and fat. Adding sugar and milk to tea increases the total energy and fat content of the diet, particularly in heavy tea drinkers.
Drinking tea without sugar added to it, or adding smaller amounts of sugar is advised. As well, it may be better to drink tea without milk so that there are more flavonoids in it, but if milk is added it is recommended you use reduced fat milk in your tea. If you choose to drink tea without milk, remember it is still important to consume dairy foods as part of a healthy diet.
