Ellen Phiddian
Cosmos science journalist
Tea is full of flavonoids: a class of substances thought to have a range of health benefits.
They also appear in fruits and vegetables like berries, oranges and apples – as well as red wine and dark chocolate.
An international team of researchers, based in Western Australia, has found a link between flavonoids and better arterial health.
The study, which looked at the diets of 881 women aged between 78 and 82, found that those who consumed a lot of flavonoids – which in this group, mainly came from black tea – were less likely to have an extensive build-up of abdominal aortic calcification (AAC).
AAC is a process in the body’s biggest artery (the aorta), and it’s a predictor of a range of health conditions including heart attacks, strokes and late-life dementia.
“This research is really exciting because it’s the first time we have seen in humans, that higher long-term dietary flavonoid intake appears to protect against vascular calcification,” says lead researcher Ben Parmenter, a researcher at Edith Cowan University’s Nutrition and Health Innovation Research Institute.
“While several studies have shown a potential link in rodents, ours is the first human study, linking total dietary flavonoid consumption with a lower propensity of the abdominal aorta to calcify.”
More on black tea and health: Black tea drinking linked to lower mortality risk
The researchers examined data from the Perth Longitudinal Study of Ageing Women, a long-term study done on older, white Western Australian women to investigate bone health and calcium intake.
“Recruitment for this study took place in 1998—back when I was in primary school!” says Parmenter.
“It was at this time that the medical examinations and participant questionnaires were collected.”
The researchers compared the diets each woman reported to their AAC.
Black tea was the biggest source of flavonoids in the study, accounting for 76% of total flavonoid intake.
Those who drank between two and six cups daily had a 16-42% lower chance of having extensive AAC.
“Out of the women who don’t drink black tea, higher total non-tea flavonoid intake also appears to protect against extensive calcification of the arteries,” says Parmenter.
More on flavonoids: Blueberries and black tea can help your gut bacteria fight the flu
Participants who had higher flavonoid intake in total had a 36-39% lower chance of extensive AAC.
But some specific flavonoid sources – red wine, fruit juice and chocolate – weren’t associated with better AAC.
Parmenter says that, since this study was done on a fairly select demographic, it’s hard to tell if the results would be similar younger people, males, or other ethnicities.
“Although we hypothesis that the benefits are likely to extend to these demographics – ultimately, further research is needed to investigate this.”
Next, the researchers are interested in looking at the relationship between flavonoids and stroke.
“We previously released findings showing that higher habitual dietary flavonoid consumption associates with lower long-term risk of stroke, but we have now gone further, to investigate specific mechanisms,” says Parmenter.