Previous research has indicated that flavanols found in cocoa have the ability to lower blood pressure and arterial stiffness as much as some blood pressure medication. However, exactly how effective they are in reducing blood pressure in everyday life has been unclear, as the studies were all conducted under tightly controlled experimental conditions. This left concerns that, used as a treatment, cocoa might unintentionally pose health risks by decreasing blood pressure when it is not raised.
Accordingly, in their new study, cardiovascular medicine expert Professor Christian Heiss of the University of Surrey and his colleagues set out to investigate the impact of cocoa flavanols outside of a clinical setting.
Prof. Heiss said: “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.
“Before we even consider introducing cocoa into clinical practice, we need to test if the results previously reported in laboratory settings safely translate into real world settings.”
To do this, the researchers recruited eleven healthy participants.
Over the course of several days, the team alternately gave each participant either six capsules containing cocoa flavanols or six placebos containing brown sugar.
Each subject was also given an upper arm blood pressure cuff and a finger clip that records so-called pulse wave velocity — a measurement of arterial stiffness.
Recordings of blood pressure and pulse wave velocity were taken prior to consumption of the day’s capsules, as well as every 30 minutes in the first three hours after ingestion.
Readings were then taken every hour for another nine hours.
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The researchers found that the participants’ blood pressure and arterial stiffness were only lowered by cocoa flavanols if such levels were already high.
When blood pressure was recorded to already be low in the morning, the cocoa treatment had no effect — meaning that these flavonols are ideal for blood pressure treatment.
Alongside this, the team also noted an effect that appeared around eight hours after the cacao was consumed — a delayed response believed to result from the way in which guy bacteria metabolise cocoa flavanols.
Prof. Heiss said: “The positive impact cocoa flavonols have on our cardiovascular system — in particular blood vessel function and blood pressure, is undeniable.”
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Prof. Heiss continued: “Doctors often fear that some blood pressure tables can decrease the blood pressure too much on some days.
“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 personalised care.”
The full findings of the study were published in the journal Frontiers in Nutrition.