Why milk adds sour note to daily cuppa …
http://www.timesonline.co.uk/section/0,,8126,00.html
It is the national drink and most of us will get through 80,000 cups of it in our lifetimes, bolstered by the knowledge that with its antioxidant qualities tea is the one habit that also does us good.
Not so, say German researchers. Once you add milk, as most Britons do, any health benefits are lost.
Previous studies have shown that drinking green or black tea can be good for you as both types contain an abundance of antioxidant substances called flavonoids. These improve blood flow and help to prevent heart disease, and are also thought to protect against some cancers.
However, adding a splash of milk to a cup of black tea counteracts the beneficial effects, the researchers say.
The study, published today in European Heart Journal, found that when black tea was drunk on its own, cardiovascular function improved. But certain proteins in milk appeared to nullify the effect of catechins, the particular flavinoids in tea.
Manufacturers have promoted the health properties of tea to Britons. It accounts for one third of Britains 1.3 billion hot drinks market.
In the study, 16 healthy post-menopausal women were given either 500ml of black tea, black tea with 10 per cent skimmed milk or, as a control, with extra boiled water.
They drank it on three occasions but refrained from drinking tea for four weeks before and after the study.
The drink itself was made from 5g of Darjeeling tea leaves brewed for three minutes.
In a healthy artery, blood vessels are able to relax if the blood flow increases a process called flow-mediated dilation (FMD). The researchers measured FMD levels in the forearm before the tea was drunk and at several intervals afterwards.
They wrote: Black tea significantly improved FMD in humans compared with water, whereas addition of milk completely blunted the effects of tea.
The culprit in milk appears to have been a group of proteins called caseins, which interacted with the tea to decrease the concentration of catechins.
But June Davison, cardiac nurse at the British Heart Foundation, said: Leaving milk out of your tea is far less likely to help protect your heart health than other measures, such as taking regular exercise, avoiding smoking and eating a healthy, balanced diet.
I’ll be Mum
- An estimated 196 million cups of tea are drunk every day in Britain
- Green and black tea contain about ten times the amount of flavinoids than fruit and vegetables, with green tea containing slightly more than black
- A recent study found that drinking five or more cups of green tea a day reduced the risk of death from heart disease by up to a quarter
- The debate on whether to pour the tea or milk first dates from the 18th century. Twinings recommends the milk first, while Tetley suggests that you add it to the tea
Source: UK Tea Council / Times database