One specific class of flavonols found in tea – flavan-3-ol – was associated with a 59% lower risk of atherosclerotic vascular disease mortality, according to findings published in the British Journal of Nutrition .
“To our knowledge, this is the first study to investigate the relationship between tea and non-tea flavonoid sources and atherosclerotic vascular disease mortality,” wrote the researchers.
They noted that they could not rule out the possibility that non-tea food sources of flavonols, such as apples, could act together to influence heart health.
“However, because consumption of non-tea flavonols was not correlated with tea intake in our cohort, it appears that the cardiovascular benefits of flavonol consumption are independent of any benefits ascribable to tea, and that flavonols may contribute to the cardiovascular benefits of tea consumption.”
The study adds to an ever-growing body of science supporting the potential benefits of tea and its constituents. To date green tea has been linked to a reduced risk of Alzheimer's and certain cancers, improved cardiovascular and oral health, as well as benefits in weight management.
Green tea contains between 30 and 40% of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10%. Oolong tea is semi-fermented tea and is somewhere between green and black tea.
The Australian researchers analyzed data from 1,063 women over the age of 75 and assessed their flavonol intakes using the US Department of Agriculture (USDA) Flavonoid, Flavone and Proanthocyanidin databases. They analyzed seven classes of flavonols, including: Flavonols, flavan-3-ols, proanthocyanidins, flavones, flavanones, anthocyanidins, and isoflavones.
During five years of follow-up, 64 deaths from atherosclerotic vascular disease were recorded, and the data indicated that women with the highest average intakes of flavonols had a 73% lower risk of death from the disease, compared with women with the lowest average intakes.
The researchers observed similar relationships for flavonols from tea (62% reduction in risk), and other non-tea sources (59% reduction). In addition, flavon-3-ols were also associated with a significant decrease in risk.
“This provides further support for the suggestion that flavonols and flavan-3-ols can contribute to cardiovascular health,” wrote scientists from the University of Western Australia.
“The cardioprotective benefits of flavonols appear to be independent of the benefits ascribable to tea consumption, suggesting that a habitual diet high in flavonols may play a role in stroke and coronary artery disease prevention.
“Ultimately, in order to make public health recommendations regarding flavonol intake, further observational and intervention trials are necessary to establish the clinical benefits of flavonol consumption, independent of tea.”
Source: British Journal of Nutrition
Published online ahead of print, FirstView Articles, doi: 10.1017/S0007114513000780
“Tea and non-tea flavonol intakes in relation to atherosclerotic vascular disease mortality in older women”
Authors: K.L. Ivey, J.R. Lewis, R.L. Prince, J.M. Hodgson