Bioactive compounds in berries can reduce high blood pressure

ScienceDaily (Jan. 15, 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 US adults.

Published next month 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 US-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 Prof 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 US. 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 randomised 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.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of East Anglia.

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Reduce High Blood Pressure Risk With These Berries

Delicious news! A new study finds that eating a cup of strawberries or blueberries a week can reduce high blood pressure risk, which is a key factor for both heart disease.

The work, intent on investigating the role regular intake of dietary flavonoids might have on the risk of high blood pressure, included over 130,000 women and 23,000 men.

The subjects supplied information about their diet by food frequency questionnaires. Besides tasting naturally sweet and delicious, berries like strawberries and blueberries are low in fat, carbs and calories, but have loads of fiber, vitamins, minerals and those powerhouse antioxidants we've all heard so much about. Anthocyanins are only one such nutrient, but there are others.

Over the 14-year period the participants were followed, the team found that 29,000 women and 5,600 men developed hypertension. But those with the highest levels of anthocyanins (a key part of both blueberries and strawberries) had an 8% lower risk for hypertension compared to those who comsumed the least amounts of these nutrient rich fruits.

Anthocyanin is a rather impressive antioxidant that gives these two delicious berries their incredible color. But it might also open blood vessels, helping blood flow more smoothly and lowers the chance for high blood pressure.

The finding even held after experts controlled for other things we know are high blood pressure risk factors. Family history, weight, how active a patient might be, and other dietary factors all play a part.

The risk reduction was most obvious in those who were under 60 years old. Why?

The research team speculates that the damage done over the years is too much for flavonoids to make much difference to blood vessel function in older people. The team points out that this suggests how important it is to eat well before middle age, so you give your body a chance to get the good for you benefits, while they still are beneficial.

Estimates from the American Heart Association have one in three adults in the U.S. being affected by high blood pressure. Another 2 million teens and children are also affected. The causes of 90-95% of high blood pressures aren't known... even though a doctor can measure your blood pressure quickly and easily in the office. Seems strange that such a potentially dangerous thing could be uncovered with such a simple, pain free test.

Research purists will point out that this new work did have some limitations. No one measured food consumed or took blood pressure levels; these measures were self reported by the study participants. This doesn't allow for the type of control that researchers like to have in experiments. The next steps will be to test doses of anthocyanins rich foods to judge the prevention of high blood pressure... to set guidelines.

In the meantime, if you're at risk and want to reduce high blood pressure risk, do something to help yourself. Prevention is the best treatment, and this comes from a healthy lifestyle... eating a nutritious diet (lots of berries/veggies, no processed foods) and not smoking. Keep those cholesterol numbers under control and do all you can to keep them that way.

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