Flavonols Found in Tea, Berries, and Cocoa May Shield Blood Vessels From Sitting’s Harmful Effects
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A new study reveals that regularly consuming foods rich in flavanols – including tea, berries, apples, and cocoa – could protect men’s blood vessels from the negative consequences of prolonged sitting. The research, conducted by the University of Birmingham, offers a potential dietary strategy to combat the rising health risks associated with increasingly sedentary lifestyles.
Modern life is characterized by extended periods of inactivity. Young adults now spend an estimated six hours a day seated, a habit known to impair vascular function. Even a modest 1% decline in this function, measured through brachial Flow-mediated dilatation (FMD), is linked to a significant 13% increase in the risk of cardiovascular diseases like heart disease, stroke, and heart attack.
Researchers initiated the study to determine if specific dietary choices, particularly those high in flavanols, could counteract the decline in vascular health that occurs during uninterrupted sitting. Flavanols are naturally occurring polyphenols found in a variety of fruits, teas, nuts, and cocoa beans, and have previously been associated with cardiovascular benefits, including support during psychological stress. The findings, published in the Journal of Physiology, build upon this existing body of evidence.
“We all spend a lot of time seated, whether at desks, behind the wheel, or relaxing at home,” explained a lead researcher from the University of Birmingham. “Even without physical movement, our bodies are under stress. Finding ways to mitigate the impact of sitting on our vascular system could significantly reduce the risk of cardiovascular diseases.”
The threat of cardiovascular disease is escalating. The British Heart Foundation reports that deaths among working-aged adults in the UK increased by 18% to 21,975 in 2023 compared to 2019. Analyses also estimate that these diseases cost the UK approximately £29 billion annually.
Testing the Protective Effects of Flavonols
To investigate whether flavanols could preserve vascular function, researchers examined their effects during a two-hour sitting period. Forty healthy young men participated, divided equally into groups with higher and lower fitness levels. Each participant consumed either a high-flavanol cocoa drink (containing 695 mg of total flavanols) or a low-flavanol cocoa drink (containing 5.6 mg of total flavanols) before the sitting session.
The study intentionally excluded women due to potential hormonal influences; fluctuations in estrogen during the menstrual cycle could affect how flavanols impact vascular function, a factor researchers acknowledge requires further investigation in future trials.
Throughout the study, the team meticulously measured several indicators of vascular health, including FMD in the superficial femoral artery and brachial artery, arterial resting shear rate and blood flow, systolic and diastolic blood pressure, and leg muscle oxygenation.
High-Flavanol Cocoa Prevents Vascular Decline
Participants who consumed the low-flavanol drink, regardless of their fitness level, experienced declines in FMD in both arm and leg arteries. They also exhibited increases in diastolic blood pressure, reductions in shear rate and blood flow, and decreased leg muscle oxygenation. These results demonstrate that physical fitness alone does not protect against the vascular effects of prolonged sitting.
In stark contrast, participants in both fitness groups who consumed the high-flavanol cocoa showed no decline in FMD in either the arm or leg arteries. This marks the first study to demonstrate that flavanols can prevent sitting-induced vascular dysfunction in healthy young men.
“Our experiment indicates that higher fitness levels do not prevent the temporary impairment of vascular function induced by sitting when only drinking low-flavanol cocoa,” stated a co-author from the University of Birmingham. “Importantly, after the high-flavanol drink, both fitter and less-fit participants maintained their FMD levels from before the two-hour sitting period.”
The research also revealed that baseline cardiorespiratory fitness does not alter the body’s response to flavanol intake, suggesting that flavanols may support vascular health irrespective of an individual’s fitness level.
Incorporating Flavonols into Daily Life
Adding flavanol-rich foods to one’s diet is surprisingly simple, according to a PhD student at the University of Birmingham. “Cocoa products processed to preserve flavanol levels are readily available in supermarkets and health stores. But cocoa isn’t the only option; fruits like apples, plums, and berries, as well as nuts, and black and green tea, are common kitchen staples.”
A senior researcher concluded, “Our research demonstrates that consuming high-flavanol foods and drinks during sedentary periods can mitigate some of the negative impacts of inactivity on the vascular system. Given the prevalence of sedentary lifestyles and the associated vascular health risks, incorporating flavanol-rich foods and drinks – alongside breaking up prolonged sitting with short walks or standing – could be a valuable strategy for enhancing long-term health, regardless of fitness level.”
