Summary: Research shows that cocoa powder reduces blood pressure and arterial stiffness, only when levels of both are elevated.
A source: University of Surrey
A new study from the University of Surrey shows that cocoa can reduce blood pressure and arterial stiffness only when it increases.
Cocoa flavanols have previously been shown to lower blood pressure and arterial stiffness, as well as some antihypertensive drugs. However, it remains unclear how effective flavanols are in lowering blood pressure in everyday life, as previous studies in this area have been conducted under strictly controlled experimental conditions.
A new study from Surrey has eased concerns that cocoa may be a health risk in the treatment of high blood pressure if blood pressure is not elevated, paving the way for its use in clinical practice.
In the first study of its kind, researchers investigated the use of cocoa flavanols to lower blood pressure and arterial stiffness in humans outside of clinical settings.
Christian Hayes, Professor of Cardiovascular Medicine at the University of Surrey:
“High blood pressure and hardening of the arteries can increase a person’s risk of heart disease and stroke, so it is vital that we explore innovative ways to treat these conditions.
“Before we can consider introducing cocoa into clinical practice, we need to make sure that the results previously reported in laboratory settings can be safely translated into real-world settings in people’s daily lives.”
Over several days, eleven healthy participants alternated between consuming six cocoa flavanol capsules or six placebo capsules containing brown sugar. Participants were given an upper arm blood pressure monitor and a finger clip measuring pulse wave velocity (PWV), a measure of arterial stiffness.
Blood pressure and PWV measurements were taken before and every 30 minutes after capsule consumption for the first three hours and then hourly for the remaining nine hours. The researchers found that blood pressure and blood pressure only decreased in participants when their blood pressure was high, but there was no effect when their blood pressure was low in the morning.
It should be noted that the effects were first detected eight hours after consuming cocoa. The researchers believe that this second peak may be related to the metabolism of cocoa flavanols by bacteria in the gut.
Professor Hayes added:
“The positive effect of cocoa flavanols on our cardiovascular system, in particular on blood vessel function and blood pressure, is undeniable. Doctors often worry that some blood pressure pills may lower blood pressure too much on certain days.
“What we found shows that cocoa flavanols only lower blood pressure when it’s elevated. Participant engagement with personal health technologies shows us that blood pressure and arterial stiffness can vary from day to day, highlighting the role of personal health monitors in designing and implementing effective personalized care.
Neuroscience and diet research news about it
Author: Natasha Meredith
A source: University of Surrey
The connection: Natasha Meredith – University of Surrey
Photo: Image is in the public domain
Original research: Open access.
“Assessing the Variability of Vascular Response to Cocoa with Personal Devices: A Series of Double-Blind Randomized Crossover n-of-1 Trials” Christian Hayes et al. Nutrition in Frontiers
Evaluation of Vascular Response Variability to Cocoa by Individual Devices: A Series of Double-Blind Randomized Crossover n-of-1 Trials
Controlled clinical intervention studies have shown that cocoa flavanols (CF) can reduce blood pressure and arterial stiffness in healthy individuals, but large variability in effect sizes has been reported across trials.
In this study, we assessed the intra- and inter-individual variability of CF responses during daily life using a series of n-of-1 trials in healthy, free-living normotensive individuals wearing personal devices.
A total of eleven healthy young controlled subjects participated in a repeated crossover randomized double-blind n-of-1 trial. For 8 consecutive days, each volunteer took alternate days 6 CF capsules (862 mg CF) on 4 days and 6 matching placebo capsules (P, 0 mg CF/day) on another 4 days in one of two randomized sequences (CF-). P-CF-P-CF-P-CF-P or P-CF-P-CF-P-CF-P-CF). Each day, the capsules were taken at the same time as breakfast after the initial measurements.
Each subject was provided with an upper arm blood pressure monitor and a finger clip measuring pulse wave velocity (PWV). Measurements of blood pressure, heart rate, and PWV were taken hourly by the participants for at least 12 hours during the day.
On the first 2 days, measurements were performed under supervision to ensure training. A general mixed model analysis showed that CF significantly decreased 12-hour systolic blood pressure and PWV by −1.4 ± 0.3 mmHg and −0.11 ± 0.03 m/s.
The peak effect was observed within the first 3 hours (1.5 h SBP: -4.9 ± 2.2 mmHg, PWV: -0.32 ± 0.17 m/s) and again 8 s post-ingestion. Large inter-individual differences were found in the responses [intra-cluster correlation coefficients (ICC): 0.41, 0.41].
In the analysis of single-person data sets, there was also significant within-day variation in individual responses that differed greatly between subjects (ICC: 0–0.30, 0–0.22, 0–0.45). Effect sizes were inversely correlated with baseline blood pressure values between and within subjects.
Evidence suggests that cocoa can lower blood pressure and arterial stiffness in everyday life when elevated within normal limits. The large inter- and intra-individual variation in responses calls for individualized nutritional strategies.