Nutrient found in tea, red wine and apples could lower blood pressure

Consuming foods and drinks that are rich in flavanols – such as apples, berries, nuts and tea – could lead to lower blood pressure, according to scientists.

Flavanols are a type of plant nutrient that have been shown to help support blood circulation and vessel health. But the scientists say that while previous studies have relied on self-reported data to draw conclusions, their research is the “first epidemiological study of this scale to objectively investigate the association between a specific bioactive compound and health”.

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The research, published in the journal Scientific Reports, is based on analysing the diet of more than 25,000 people in Norfolk.

“What this study gives us is an objective and significant finding about the association between flavanols – found in tea and some fruits – and blood pressure,” said Professor Gunter Kuhnle, a nutritionist at the University of Reading who led the research.

“This research confirms the results from previous dietary intervention studies and shows that the same results can be achieved with a habitual diet rich in flavanols.

“In the British diet, the main sources are tea, cocoa, apples and berries.”

An international team of researchers, including experts from the University of Reading and Cambridge University, looked at 25,618 participants from the European Prospective Investigation into Cancer (EPIC) Norfolk study, who have been providing information about their diet, lifestyle and health for more than two decades.

The team measured the participants’ flavanol intake using nutritional biomarkers. These are biological indicators of dietary intake and metabolism which are present in the blood.

“Using nutritional biomarkers to estimate intake of bioactive food compounds has long been seen as the gold standard for research, as it allows intake to be measured objectively,” said Prof Kuhnle.

“The development, validation and application of the biomarker was only possible because of the long-term commitment of all collaborators.”

Based on their findings, the researchers said if the general public increased its flavanol intake, there could be an overall reduction in cardiovascular disease incidence.

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Dr Ian Johnson, nutrition researcher and Emeritus Fellow at the Quadram Institute in Norwich, described the findings as “an important, high-quality investigation of some physiological effects of dietary flavonoids”.

“The authors have been able to show that systolic blood pressure was lower in participants consuming the highest quantities of flavonoids, compared to those consuming the lowest,” said Dr Johnson.“This is a potentially important observation because it is consistent with the growing evidence from randomised controlled human intervention trials showing that relatively high doses of certain flavonoids can exert a blood-pressure lowering effect.”

But Dr Johnson, who was not involved in the research, added that despite all its strengths, the observational study does not show that a high flavonoid intake causes blood pressure to drop – only that there is a link between the two.

“The authors have done their best to control for other factors that might account for their results, but they are right to state that large-scale intervention trials will be required to test the hypothesis that the observed differences in blood pressure can be explained by differences in flavonoid intake.”