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Study confirms: cocoa reduces high blood pressure

Several studies have found that cocoa flavanols are as efficient in lowering blood pressure and arterial stiffness as many blood pressure medication. However, since these studies have been performed in tightly controlled experimental settings, how effective flavanols are in everyday life has remained unknown. Moreover, some scientists voiced concerns that using cocoa as a treatment for high blood pressure could pose health risks by decreasing the pressure when it is not raised. 

Now, for the first time, a research team from the University of Surrey has set out to investigate the effects of cocoa flavanols on lowering blood pressure and arterial stiffness in individuals outside clinical settings. The analysis revealed that cocoa only reduces blood pressure and arterial stiffness when elevated, thus paving the way for it to be safely used in clinical practice.

“High blood pressure and arterial stiffness increases a person’s risk of heart disease and strokes, so it is crucial that we investigate innovative ways to treat such conditions,” said study senior author Christian Heiss, a professor of Cardiovascular Medicine at the University of Surrey. “Before we even consider introducing cocoa into clinical practices, we need to test if the results previously reported in laboratory settings safely translate into real-world settings, with people going about their everyday lives.”

Professor Heiss and his team enrolled 11 healthy participants and asked them to consume, on alternating days, either six cocoa flavanol capsules or six placebo ones containing only brown sugar. The participants were provided with an upper arm blood pressure monitor and finger clip measuring pulse wave velocity (PWV), which shows the levels of arterial stiffness. These measurements were taken before the consumption of the capsules, every 30 minutes after ingestion in the first three hours, and hourly for the remaining nine hours.

The measurements revealed that blood pressure and arterial stiffness were only lowered in participants if it was high, with no effect occurring when the pressure was already low in the morning. Moreover, significant effects in people with initially high blood pressure were identified also at eight hours after taking the pills, which is probably due to how gut bacteria metabolize cocoa flavanols.

“The positive impact cocoa flavanols have on our cardiovascular system, in particular, blood vessel function and blood pressure, is undeniable. Doctors often fear that some blood pressure tablets can decrease the blood pressure too much on some days,” said Professor Heiss.

“What we have found indicates that cocoa flavanols only decrease blood pressure if it is elevated. Working with participants’ personal health technologies showed us how variable blood pressure and arterial stiffness can be from day to day and shows the role of personal health monitors in developing and implementing effective personalized care,” he concluded.

The study is published in the journal Frontiers in Nutrition.

By Andrei Ionescu, Staff Writer  

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