The authors, from East Anglia University, England, and Harvard University, USA, explained that hypertension is one of the most common cardiovascular diseases on this planet. People with high blood pressure have a greater risk of developing heart disease and stroke. The condition is estimated to cost over $300 billion globally, every year. One in every three adults in the USA has hypertension. Approximately 10 million individuals in the United Kingdom suffer from hypertension.
Anthocyanin-rich blueberries can help reduce people's risk of developing hypertension. The researchers found that regular eaters had a 10% lower chance of having high blood pressure compared to those who did not eat blueberries. A regular blueberry eater consumes them at least once a week.
Anthocyanins are part of a parent class of molecules called flavonoids, which are odorless and flavorless. They give foods a moderately astringent sensation. Anthocyanins can be found in all higher plants - in their stems, roots, flowers, leaves and fruits. They can be found in high amounts in herbs, grains, and many fruits and vegetables. Anthocyanin-rich foods include blackberries, blueberries, raspberries, strawberries, plums, cabbage, red onion and blood orange juice.
Flavanoids are present in many teas, fruit juices, dark chocolates and red wine, and have been shown to reduce cardiovascular disease risk.
The authors explained that their study was the first to focus on whether flavonoids had any impact in reducing hypertension risk.
Scientists from Harvard and East Anglia universities gathered data from the Nurses' Health Study and the Health Professionals Follow-up Study which included 47,000 adult males and 134,000 adult females over a 14-year period. They were all hypertension-free at the beginning of the study. They completed questionnaires every two years which asked questions about their health and eating habits. They were assessed every four years. The investigators then compared the incidence of newly diagnosed hypertension to flavonoid consumption over the 14-year period.
35,000 individuals developed hypertension. They found that tea was the main dietary contributor of flavonoids, as well as blueberries, orange juice, apples, red wine and strawberries. They then focused on dietary intake of anthocyanins and found an 8% difference in hypertension risk among the highest and lowest consumers of this compound. Protection from hypertension was even greater among individuals aged less than 60 years.
Those who ate blueberries at least once a week had a 10% lower risk of developing hypertension than people who never ate them.
Regular blueberry consumers had better protection than regular strawberry consumers, the authors added.
Lead author, Prof. Aedin Cassidy, said:
"Our findings are exciting and suggest that an achievable dietary intake of anthocyanins may contribute to the prevention of hypertension. 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 scientists plan to carry out a further study, a randomized controlled trial, to identify different sources of anthocyanins and determine what the ideal doses for hypertension prevention are.
Source: University of East Anglia, England