We all know sitting too much is not good for our health. But for many of us, it's our reality - sit all day at work, and then come home and relax by sitting all evening. But there is some good news. A recent study found that eating foods rich in flavanols, such as cocoa, may protect our blood vessels from the harms of too much sitting.
While the research occurred in young healthy men (with either high or low levels of fitness), all had detrimental effects in their vascular health (blood flow) after several hours of sitting. Drinking a flavanol rich cocoa drink at the beginning of a 2 hour sitting time prevented the decrease in blood flow ("sitting-induced vascular dysfunction") in both upper and lower limbs.
The researchers did point out though, that some exercise every hour, even 5 minutes of walking or climbing stairs, would have the same effect.
Flavanols are naturally occurring polyphenols found in various fruits (e.g., blueberries, apples, grapes), green and black tea, matcha, nuts, red wine, and cocoa beans. They have previously been linked to cardiovascular benefits, including support for the vascular system during psychological stress. Eating diverse flavanoid rich foods is best because there are so many types of flavanols.
From Science Daily: Cocoa and tea may protect your heart from the hidden damage of sitting
New findings from the University of Birmingham suggest that regularly eating foods rich in flavanols, including tea, berries, apples, and cocoa, may help protect men's blood vessels from the negative effects that occur during long periods of sitting.
Sedentary habits are widespread in modern life. Young adults spend an estimated six hours a day seated, and extended sitting is known to reduce how well blood vessels function.
Earlier research has shown that even a small 1% drop in vascular function, measured through brachial Flow-mediated dilatation (FMD), corresponds to a 13% rise in the risk of cardiovascular conditions such as heart disease, strokes, and heart attacks.
Researchers in the new study set out to determine whether specific dietary choices, particularly foods high in flavanols, could help offset the decline in vascular health that occurs during uninterrupted sitting.
Flavanols are naturally occurring polyphenols found in various fruits, tea, nuts, and cocoa beans. They have previously been linked to cardiovascular benefits, including support for the vascular system during psychological stress.
Dr. Catarina Rendeiro, Assistant Professor in Nutritional Sciences at the University of Birmingham and 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."
To explore whether flavanols could help preserve vascular function, the researchers examined the effects of these compounds during a two-hour sitting period. Forty healthy young men took part. Twenty had higher fitness levels and 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 beginning the sitting session.
Women were not included in the study because fluctuations in estrogen during the menstrual cycle may influence how flavanols affect vascular function. The researchers note that this should be explored in future trials.
Before and after the sitting period, the team measured several indicators of vascular health, including: FMD in the superficial femoral artery and the brachial artery, arterial resting shear rate and blood flow, systolic and diastolic blood pressure, leg muscle oxygenation
Both the higher and lower fitness groups who consumed the low-flavanol drink showed declines in FMD in the arteries of their arms and legs. These participants also experienced increases in diastolic blood pressure, reductions in shear rate and blood flow, and lower leg muscle oxygenation. The results indicate that simply being more physically fit does not protect against the vascular effects of prolonged sitting.
In contrast, participants in both fitness groups who consumed the high-flavanol cocoa did not show 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 results also show for the first time that baseline cardiorespiratory fitness does not change how the body responds to flavanol intake. This suggests that flavanols may help support vascular health regardless of someone's fitness level.