In a new study, scientists have found that intake of diets rich in flavan-3-ol can help lower high blood pressure in people diagnosed with hypertension. The diet high in particular chemical should be rich in berries, tea, and apples. This was found as the result of the first UK study making objective measures of thousands of UK residents’ eating habits.
Scientists found that such flavan-3-ol high diets that can also contain cocoa and red wine are also associated with lower risk factors for cardiovascular disease. The study was published in Scientific Reports and partially funded by the confectionery firm Mars.
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This study was different from previously studied cohorts as it measured flavan-3-ol intake using nutritional biomarkers. However, in previous studies the data was based on self-reported food diaries. Nutritional biomarkers can be objectively measured in different biological samples to indicate nutritional intake.
The new study looked for evidence of two flavan-3-ol biomarkers in urine samples from 25,618 adults in Norfolk and compared it with their blood pressure.
The team found that difference in blood pressure between those with the lowest 10% of flavan-3-ol intake and those with the highest 10% of intake was between 2 and 4mmHg.
The association between flavan-3-ol intake and blood pressure remained fairly stable even after taking out lifestyle factors such as smoking and physical activity out of equation, according to the study’s lead author, Prof Gunter Kuhnle, a nutritionist at the University of Reading.
Kuhnle also described that the way flavan-3-ol is consumed is also crucial. He explained, “Sometimes I see people saying you should consume chocolate to get healthy flavan-3-ols, but to get to the amount you need to find an effect, you would have to eat so much … you just couldn’t”.
What he meant was that eating large amounts of foods high in sugar and fat could wipe out the effects of beneficial flavan-3-ols.
The research team found that the effect was more pronounced in participants with hypertension. Women also had stronger improvements than men. Though scientists could not see the reason behind it. The researchers added that further study was needed to conclusively prove that higher flavan-3-ol intake directly causes improvements in blood pressure.
Critics of the study like Dr Ian Johnson, nutrition researcher at Quadram Institute Bioscience, said, “Although statistically significant, the differences in blood pressure that have been observed are relatively small.”
The researchers compared the biomarker results with seven-day food diaries compiled by the participants. The variability in food composition was immense. One cup of tea is generally considered to contain 180 milligrams of flavan-3-ols.
“But if you look at actual reported content, it’s anywhere between nought and about 600 milligrams,” Kuhnle said. “And so the idea that we have sort of standardised food, which we can then use from a food diary or food questionnaire to estimate how much flavan-3-ol most people consume, turned out to be more wishful thinking.”
In the study, the researchers found virtually no uniformity between biomarker-estimated flavan-3-ol intake and the seven-day food diaries. They also found there were no consistent, significant associations between flavan-3-ol biomarker-estimated intake and cardiovascular disease or death.