Flavanols & Sitting: Protect Blood Vessels with Tea, Berries & Cocoa | University of Birmingham Study

The simple act of sitting for extended periods, a hallmark of modern life, can temporarily impair blood vessel function. But emerging research from the University of Birmingham suggests a surprisingly accessible countermeasure: flavanol-rich foods like cocoa and tea. A new study, published in the Journal of Physiology, indicates that consuming flavanols before or during prolonged sitting may assist protect cardiovascular health, regardless of an individual’s fitness level.

How Sitting Impacts Vascular Health

Young adults spend roughly six hours a day seated, and this prolonged inactivity isn’t benign. Research demonstrates that even short periods of sitting can reduce the ability of blood vessels to dilate properly – a process called flow-mediated dilatation (FMD). A mere 1% drop in FMD is linked to a 13% increased risk of cardiovascular events like heart disease and stroke. This underscores the importance of understanding how to mitigate the negative effects of sedentary behavior, which is increasingly prevalent in modern societies.

Flavanols, naturally occurring compounds found in cocoa, tea, berries, apples, and certain nuts, have been previously associated with cardiovascular benefits. Earlier studies suggested they could offer protection during periods of mental stress, and now, this new research points to a role in combating the vascular consequences of physical inactivity. The University of Birmingham team sought to determine if dietary flavanol intake could preserve blood vessel function during uninterrupted sitting.

The Study Design: Cocoa and Sitting

The study involved forty healthy young men, divided into two groups based on fitness level (twenty high-fit and twenty low-fit). Participants 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 a two-hour sitting session. Researchers then measured several key indicators of vascular health, including FMD in both the superficial femoral artery (in the leg) and the brachial artery (in the arm), arterial resting shear rate and blood flow, blood pressure, and leg muscle oxygenation.

It’s important to note that the study population was limited to young men. Researchers acknowledge that hormonal fluctuations during the menstrual cycle could influence how flavanols affect vascular function in women, and future research should include female participants. This limitation is explicitly stated in the study publication.

Key Findings: Flavanols Preserve Blood Vessel Function

The results revealed a significant difference between the two groups. Those who consumed the low-flavanol cocoa experienced declines in FMD in both the arm and leg arteries, along with increases in diastolic blood pressure, reductions in shear rate and blood flow, and lower leg muscle oxygenation. Critically, these negative effects were observed regardless of fitness level, suggesting that physical fitness alone doesn’t protect against the vascular impact of prolonged sitting.

Though, participants who consumed the high-flavanol cocoa showed no such declines in FMD. This is the first study to demonstrate that flavanols can actively prevent sitting-induced vascular dysfunction in healthy young men. Dr. Sam Lucas, a co-author of the study, emphasized this finding: “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.” (PubMed)

What Do Flavanols Actually Do?

Flavanols are a type of polyphenol, a class of plant compounds known for their antioxidant and anti-inflammatory properties. Whereas the exact mechanisms by which flavanols protect blood vessel function are still being investigated, it’s believed they enhance the production of nitric oxide, a molecule that helps blood vessels relax and dilate. This improved blood flow contributes to better vascular health. (University of Birmingham)

Beyond Cocoa: Dietary Sources of Flavanols

While the study specifically used cocoa, it’s important to remember that flavanols are found in a variety of readily available foods. Alessio Daniele, a PhD student at the University of Birmingham, points out that “This proves 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.”

Implications for Public Health and Future Research

The findings have important implications for public health, given the widespread prevalence of sedentary lifestyles. Cardiovascular disease remains a leading cause of death globally, and the UK has seen a concerning rise in cardiovascular-related deaths among working-aged adults, increasing by 18% between 2019 and 2023. (University of Birmingham) Incorporating flavanol-rich foods into daily routines, particularly during periods of inactivity, could be a simple yet effective strategy to mitigate some of the vascular risks associated with prolonged sitting.

Dr. Catarina Rendeiro emphasizes that combining flavanol intake with regular movement is ideal: “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.”

Further research is needed to explore the optimal dosage of flavanols, the long-term effects of regular consumption, and the potential benefits for diverse populations, including women and older adults. Researchers are also investigating whether flavanol supplementation could be a viable strategy for individuals at higher risk of cardiovascular disease. The British Heart Foundation continues to fund research into cardiovascular health and provides resources for the public on maintaining a healthy heart. (University of Birmingham)

What to consider going forward: Ongoing trials will likely focus on refining dietary recommendations and exploring the potential for personalized interventions based on individual risk factors and lifestyle habits. Public health campaigns may also emphasize the importance of incorporating flavanol-rich foods into daily routines as part of a broader strategy to promote cardiovascular health and combat the negative effects of sedentary behavior.