How might black tea protect against heart disease?

 Researchers from the University of L’Aquila, in Italy report it improves blood vessel reactivity, while reducing stiffness.

First, the details.

• 19 healthy men took 5 treatments twice daily for 1 week each in random order.
• Black tea containing 0, 100, 200, 400, and 800 mg tea flavinoids/day.
• A cup of black tea contains 100 to 200 mg of flavonoids, depending on how it’s brewed.
• The participants avoided other flavonoid-containing foods.
• The main outcome measured was brachial artery flow-mediated dilation — the standard for assessing endothelium dysfunction.
• Endothelium is the layer of cells lining blood vessels that contact flowing blood.

And, the results.

• Black tea increased blood vessel dilation.
• Higher amounts of flavonoids resulted in greater effects by about 1% to 2% compared to the tea that didn’t contain flavonoids.
• The difference in response between 0 mg and 100 mg of flavonoids was significant.
• The differences in response with the highest dose of flavonoids (800 mg) vs, 0 mg, 100 mg, and 200 mg were significant.
• Black tea significantly decreased systolic and diastolic blood pressure and vessel stiffness.

The bottom line?
The authors concluded, “Our study is the first showing black tea ingestion dose-dependently improved flow-mediated dilation and decreased peripheral arterial stiffness in healthy volunteers. Our data suggest that… all tea drinkers could benefit from protective cardiovascular effects exerted by tea.”

Recently, it was reported that drinking at least 3 cups of black or green tea was associated with a 21% lower risk of stroke compared to consuming less than a cup a day.

4/12/09 19:15 JR