Flavanol-rich foods like cocoa and tea may offer an easy way to guard your heart during long stretches of sitting. Credit: Stock
New research from the University of Birmingham indicates that regularly eating foods high in flavanols, such as tea, berries, apples, and cocoa, may help support vascular health in men during extended periods of sitting.
Sitting for long stretches is a common part of modern life. Young adults are estimated to spend around six hours per day seated, and this amount of inactivity has been shown to reduce how well blood vessels function.
Earlier work has demonstrated that even a small 1% drop in vascular function, measured by brachial Flow-mediated dilatation (FMD), is linked to a 13% increase in the risk of cardiovascular disease. Conditions such as heart disease, strokes, and heart attacks all fall within this category.
Researchers in the new study wanted to determine whether dietary choices, particularly foods naturally rich in flavanols, could help protect the vascular system from the effects of sitting without breaks.
Understanding Flavanols and Their Potential Health Benefits
Flavanols are a group of polyphenol compounds found in several plant-based foods, including fruits, tea, nuts, and cocoa beans. Previous studies have shown that these compounds can benefit cardiovascular health, including helping protect blood vessels during times of mental stress.
The new research has been published in the Journal of Physiology.
Catarina Rendeiro, Assistant Professor in Nutritional Sciences at the University of Birmingham and the study’s lead author, explained: “Whether we are sitting at desks, behind the wheel of a car, on a train, or on the sofa reading a book or watching TV, we all spend a lot of time seated. Even though we are not moving our bodies, we are still putting them under stress. Finding ways to mitigate the impact that sitting for uninterrupted periods has on our vascular system could help us cut the risk of developing cardiovascular diseases.”
Testing Flavanols as a Strategy to Reduce Sitting-Related Vascular Declines
To investigate whether flavanols could help maintain vascular health, the researchers examined the effects of consuming them before a controlled sitting period. Forty healthy young men took part. Twenty of them had high fitness levels, and the other twenty had lower fitness levels. Each participant consumed either a high-flavanol cocoa drink (695 mg of total flavanols per beverage) or a low-flavanol cocoa drink (5.6 mg of total flavanols per beverage) before completing a two-hour sitting trial.
Women were not included in the study because hormonal changes during the menstrual cycle may influence how flavanols affect vascular function. The researchers note that this should be explored in future studies.
Before and after the sitting period, the team collected several vascular measurements, including:
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FMD in the superficial femoral artery and the brachial artery
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Arterial resting shear rate and blood flow
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Systolic and diastolic blood pressure
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Leg muscle oxygenation
High-Flavanol Cocoa Prevents Blood Vessel Function Decline
Participants in both fitness groups who consumed the low-flavanol beverage before sitting showed declines in FMD in the arteries of their arms and legs. The low-flavanol drink was also associated with increased diastolic blood pressure, reduced shear rate and blood flow, and lower muscle oxygenation in the legs. These findings indicate that higher fitness levels do not protect against the vascular effects of uninterrupted sitting.
However, the group that consumed the high-flavanol cocoa did not experience declines in FMD in either the arm or leg arteries. This is the first study to demonstrate that flavanols can prevent sitting-induced vascular dysfunction in healthy young men.
Dr. Sam Lucas, Professor of Cerebrovascular, Exercise & Environmental Physiology at the University of Birmingham and co-author, said: “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. Importantly, after the high-flavanol drink, both fitter and less-fit participants kept their FMD the same as it was before sitting for two hours.”
The findings also show that the vascular benefits of flavanol intake are not influenced by baseline cardiorespiratory fitness. This suggests that flavanols may help support vascular health across a wide range of activity levels.
Simple Ways to Add Flavanols to Everyday Diets
Alessio Daniele, PhD student at the University of Birmingham, explained: “It is actually quite easy to add high flavanol foods to your diet. There are cocoa products available in supermarkets and health stores which are processed through methods that preserve flavanol levels. If cocoa isn’t your thing, fruits like apples, plums and berries, nuts, and black and green tea are all common kitchen staples and are readily available.”
Dr. Catarina Rendeiro concluded: “Our research shows that consuming high-flavanol foods and drinks during periods spent sitting down is a good way to reduce some of the impact of inactivity on the vascular system.
“Given how common sedentary lifestyles have become and the increased risk this can have to vascular health, using flavanol-rich food and drink, especially in combination with breaking up periods of inactivity by going for a short walk or standing up, could be a good way to enhance long-term health, no matter the individual’s fitness level.”
Reference: “Dietary flavanols preserve upper- and lower-limb endothelial function during sitting in high- and low-fit young healthy males” by Alessio Daniele, Samuel J. E. Lucas and Catarina Rendeiro, 29 October 2025, The Journal of Physiology.
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