“We have linked the powerful effects of blueberries in helping to reduce blood pressure and improve blood vessel function to the blue colored anthocyanins they contain,” said University of Surrey’s Professor Christian Heiss, senior author of the study.
“It is important that we have a balanced diet with plenty of fruit and vegetables which will provide our body with important bioactives that may help to maintain physiological functions and allow healthy aging.”
Professor Heiss and colleagues studied 40 healthy volunteers for one month. They were randomly given either a drink containing 200 g of blueberries, or a matched control drink daily.
The researchers monitored chemicals in participants’ blood and urine as well as their blood pressure and flow-mediated dilation of the brachial artery: a measure of how the artery widens when blood flow increases, which is considered a sensitive biomarker of cardiovascular disease risk.
In a further study, they compared the effects of a blueberry drink with those of purified anthocyanins, a type of phytochemical responsible for the blue, red, pink and purple color of some fruits and vegetables such as berries and red grapes.
They also compared this with control drinks containing either similar levels of fiber, mineral or vitamins found in blueberries.
“Effects on blood vessel function were seen two hours after consumption of the blueberry drinks and were sustained for one month even after an overnight fast,” the scientists said.
“Over the course of the month, blood pressure was reduced by 5 mmHg. This is similar to what is commonly seen in studies using blood pressure lowering medication.”
“The drinks containing purified anthocyanins led to improvements in endothelial function. Endothelial cells act as a barrier between the blood or lymph and the surrounding body tissue, as well as playing key roles in blood clotting and regulating blood pressure.”
“Neither the control drink, the control with fiber or the control with minerals and vitamins had a significant effect on flow-mediated dilation at two and six hours after consumption.”
“Although it is best to eat the whole blueberry to get the full benefit, our study finds that the majority of the effects can be explained by anthocyanins,” said study first author Dr. Ana Rodriguez-Mateos, a researcher at King’s College London and the University Düsseldorf.
“If the changes we saw in blood vessel function after eating blueberries every day could be sustained for a person’s whole life, it could reduce their risk of developing cardiovascular disease by up to 20%.”
Ana Rodriguez-Mateos et al. Circulating Anthocyanin Metabolites Mediate Vascular Benefits of Blueberries: Insights From Randomized Controlled Trials, Metabolomics, and Nutrigenomics. Journals of Gerontology: Series A, published online February 16, 2019; doi: 10.1093/gerona/glz047