We’re often told to move more—by exercising, stretchin, or simply standing up—to combat the effects of prolonged sitting. But what we eat may also play a key role in offsetting the negative impacts of a sedentary lifestyle.
This is the conlcusion of a team of researchers from the University of Birmingham in England, who discovered that eating flavanol-rich foods—such as tea, berries, apples and cocoa—can help protect vascular health in men from the harmful effects of prolonged sitting.
The average American spends about 9.5 hours a day sitting, a habit linked to a higher risk of heart disease and the buildup of plaque in the arteries. Prolonged sitting can also disrupt blood flow and trigger subtle changes in how blood vessels function and how key molecules in the body are balanced.
“Our work suggests that drinking or eating a food high in flavanols can be used as a strategy to mitigate some of the negative impact of sitting on the body’s arteries,” paper author and nutritional scientist professor Catarina Rendeiro told Newsweek.
“This can help us make more informed decisions about what we eat and drink during periods in which we have to sit down uninterrupted for a period.”
How Flavanols Work in the Body
“The main mechanism by which flavanols act within the vasculature in these short time frames is by enhancing the availability of a vasodilator called nitric oxide (NO), which is known to improve vascular function,” Rendeiro explained.
She said that evidence suggests the flavanol (−)-epicatechin—a natural compound found in foods like dark chocolate, cocoa and green tea—can help the body produce more nitric oxide, a molecule that relaxes and widens blood vessels to improve circulation and support heart health.
It does this by increasing the bioavailability of nitric oxide, meaning it boosts how much of this helpful molecule is available in the body. The process involves activating eNOS (endothelial nitric oxide synthase) — the enzyme responsible for producing nitric oxide — through a chain of calcium-dependent signaling pathways, which are like internal messages telling the cells to “turn on” nitric oxide production.
Previous research has shown that even a 1 percent drop in vascular function—measured by Flow-Mediated Dilatation (FMD), which reflects how flexible arteries are—can raise the risk of heart disease, stroke, and heart attacks by 13%.
The study involved 40 healthy young men—20 with higher fitness levels and 20 with lower levels. Each participant drank either a high-flavanol cocoa drink (695 mg total flavanols) or a low-flavanol version (5.6 mg) before sitting for two hours.
The team measured several indicators before and after sitting, including:
- FMD in arm and leg arteries
- Blood pressure
- Blood flow
- Leg muscle oxygenation
Women were not included in this study because hormonal changes during the menstrual cycle may influence how flavanols affect vascular health, which researchers plan to study in the future.
Newsweek also spoke to Sarah Hanratty, a clinical and public health nutritionist, who was not involved in the study.
She said: “Animal studies suggest that men and women may respond to flavanols differently. Perimenopause, estrogen seems to significantly increase the positive impact of flavanols on cardiovascular function.
“This would change after menopause when estrogen drops and a woman’s cardiovascular risk increases. This suggests that women who have gone through menopause would benefit more from increasing flavanol intake.”
The Study Results
Both the high- and low-fitness groups who drank the low-flavanol cocoa experienced declines in blood vessel function, increased blood pressure and reduced muscle oxygenation. This suggests that fitness alone does not protect the body from the effects of sitting.
However, the groups who drank the high-flavanol cocoa maintained healthy blood vessel function throughout the two-hour sitting period. This is the first study to show that flavanols can prevent sitting-induced vascular dysfunction in young, healthy 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,” said paper co-author and integrative physiologist professor Sam Lucas.
“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.”
Overall, the findings suggest that incorporating simple, healthy dietary habits—such as drinking a cup of green or black tea, eating fruit or consuming cocoa—can help counteract some of the negative effects that prolonged sitting has on blood vessel health.
These flavanol-rich foods appear to benefit blood vessel function regardless of fitness level, highlighting how small, everyday dietary choices can play a meaningful role in protecting heart health during periods of inactivity, like long meetings or desk work.
Do you have a tip on a health story that Newsweek should be covering? Do you have a question about flavanols? Let us know via health@newsweek.com.
References
Margalef, M., Pons, Z., Iglesias-Carres, L., Arola, L., Muguerza, B., & Arola-Arnal, A. (2016). Gender-related similarities and differences in the body distribution of grape seed flavanols in rats. Molecular Nutrition & Food Research, 60(4), 760–772. https://doi.org/10.1002/mnfr.201500717
Pekas, E. J., Allen, M. F., & Park, S.-Y. (2023). Prolonged sitting and peripheral vascular function: Potential mechanisms and methodological considerations. Journal of Applied Physiology, 134(4), 810–822. https://doi.org/10.1152/japplphysiol.00730.2022
Vanhatalo, A., Burnley, M., & Jones, A. M. (2025). Fitness adaptation to sprint interval training and continuous running in older adults. The Journal of Physiology. https://doi.org/10.1113/JP286845
