Journal of Physiology: Cocoa Protects Blood Vessels from the Effects of Prolonged Sitting

A recent study published in the Journal of Physiology has shown that sitting for several hours impairs blood vessel function, but this effect can be significantly reduced by consuming foods rich in cocoa flavanols.

A sedentary lifestyle—common in modern society—is associated with an increased risk of cardiovascular disease and other chronic conditions, as prolonged physical inactivity negatively affects the endothelium, the inner lining of blood vessels that regulates blood flow, inflammation, and blood clotting.

Researchers from the University of Birmingham conducted a study involving young, healthy men aged 18 to 34. Participants were divided into two groups based on physical fitness level—high and low endurance—and were observed during two hours of uninterrupted sitting after consuming a beverage: one rich in cocoa flavanols and the other low in these compounds.

During the experiment, vascular function was assessed using a method called flow-mediated dilatation (FMD), which reflects the ability of blood vessels to widen in response to increased blood flow. After two hours of sitting, participants who consumed the low-flavanol beverage showed a reduction in FMD in the arteries of both the upper and lower limbs, indicating impaired vascular function. In contrast, those who drank the high–cocoa-flavanol beverage did not experience this decline, and their FMD values remained closer to baseline levels.

The results also confirmed that physical fitness did not protect blood vessels from the negative effects of prolonged sitting when participants consumed the low-flavanol drink: vascular function deteriorated in both fitness groups. At the same time, flavanols were equally effective in participants with both high and low fitness levels.

The authors suggest that consuming flavanol-rich foods—such as dark chocolate, cocoa, tea, apples, and berries—immediately before a prolonged period of sitting may serve as a simple dietary way to partially protect blood vessels from temporary impairments caused by inactivity. This does not replace the need for regular physical activity, but it may be a useful additional approach for people who are required to sit for long periods, such as at a desk job.

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