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Berry compounds can reduce high blood pressure

January 17, 2011 – Eating
blueberries can guard against high blood pressure, according to new research by
the University of East Anglia (UEA) and Harvard University.

January 17, 2011 – Eating
blueberries can guard against high blood pressure, according to new research by
the University of East Anglia (UEA) and Harvard University.

High blood pressure – or
hypertension – is one of the major cardiovascular diseases worldwide. It leads
to stroke and heart disease and costs more than $300 billion each year. Around
a quarter of the adult population is affected globally – including 10 million
people in the UK and one in three U.S. adults.

Published February 2011 in
the American Journal of Clinical Nutrition, the new findings show that
bioactive compounds in blueberries called anthocyanins offer protection against
hypertension. Compared with those who do not eat blueberries, those eating at
least one serving a week reduce their risk of developing the condition by 10
per cent.

Anthocyanins belong to the
bioactive family of compounds called flavonoids and are found in high amounts
in blackcurrants, raspberries, aubergines, blood orange juice and blueberries.
Other flavonoids are found in many fruits, vegetables, grains and herbs. The
flavonoids present in tea, fruit juice, red wine and dark chocolate are already
known to reduce the risk of cardiovascular disease.

This is the first large
study to investigate the effect of different flavonoids on hypertension.

The team of UEA and
Harvard scientists studied 134,000 women and 47,000 men from the Harvard
established cohorts, the Nurses’ Health Study and the Health Professionals
Follow-up Study over a period of 14 years. None of the participants had
hypertension at the start of the study. Subjects were asked to complete health
questionnaires every two years and their dietary intake was assessed every four
years. Incidence of newly diagnosed hypertension during the 14-year period was
then related to consumption of various different flavonoids.

During the study, 35,000
participants developed hypertension. Dietary information identified tea as the
main contributor of flavonoids, with apples, orange juice, blueberries, red
wine, and strawberries also providing important amounts. When the researchers
looked at the relation between individual subclasses of flavonoids and
hypertension, they found that participants consuming the highest amounts of
anthocyanins (found mainly in blueberries and strawberries in this U.S.-based
population) were eight per cent less likely to be diagnosed with hypertension
than those consuming the lowest amounts. The effect was even stronger in participants
under 60.

The effect was stronger
for blueberry rather than strawberry consumption. Compared to people who ate no
blueberries, those eating at least one serving of blueberries per week were 10
per cent less likely to become hypertensive.

“Our findings are exciting
and suggest that an achievable dietary intake of anthocyanins may contribute to
the prevention of hypertension,” said lead author Professor Aedin Cassidy of
the Department of Nutrition at UEA’s Medical School.

“Anthocyanins are readily
incorporated into the diet as they are present in many commonly consumed foods.
Blueberries were the richest source in this particular study as they are
frequently consumed in the U.S. Other rich sources of anthocyanins in the UK
include blackcurrants, blood oranges, aubergines and raspberries.”

The next stage of the
research will be to conduct randomized controlled trials with different dietary
sources of anthocyanins to define the optimal dose and sources for hypertension
prevention. This will enable the development of targeted public health
recommendations on how to reduce blood pressure.