Heart benefits of Tea

Written by: 
Dr Sarah Brewer

Green, white and black tea are similar in that they are made from the young leaves and leaf buds of the same shrub, Camellia sinensis.

Green tea is made by steaming and drying fresh tea leaves immediately after harvesting, while black tea is made by crushing and fermenting freshly cut tea leaves so that they oxidize before drying. This allows natural enzymes in the tea leaves to produce the characteristic red-brown colour and reduced astringency. 

White tea is similar to green tea in that it is not fermented, but it is only made from new tea buds, picked before they open. These have a white appearance that is due to the presence of fine, silvery hairs.

White tea contains around 15mg of caffeine per cup, compared with 20mg for green tea and 40mg for black tea. 

The benefits

Over 30 per cent of the dry weight of green tea leaves consists of powerful flavonoid antioxidants called catechins. These are converted into less active antioxidants during fermentation but even so, drinking four to five cups of black tea per day provides over 50 per cent of the total dietary intake of flavonoid antioxidants (other sources include fruit and vegetables, especially apples and onions).

Drinking tea has beneficial effects on blood lipids, blood pressure and blood stickiness. A large analysis of all the data suggests that drinking three cups of tea per day may reduce the risk of a heart attack by 11 per cent [1] and of a stroke by 21 per cent [2]. Long-term tea-drinking may also help to control levels of glucose and protect against type 2 diabetes. [3].  

References: 

1. http://www.ncbi.nlm.nih.gov/pubmed/11549554

2. Arab L et al. Stroke. 2009;40(5):1786-92 http://www.ncbi.nlm.nih.gov/pubmed/19228856

3. Pangiotakos D B et al. Yonsei Med. J. 2009;50(1):31-8 http://www.ncbi.nlm.nih.gov/pubmed/19259345