Researchers at King’s College London have found that eating blueberries may help to lower blood pressure. Daily consumption of the berries over the course of a month was associated with improved blood vessel function and a lowering of systolic blood pressure.
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An analysis of the results suggests the beneficial cardiovascular effects are mediated by antioxidants called anthocyanins – the phytochemicals that give blueberries their color.
In the US, high blood pressure (hypertension) is estimated to affect about one in three adults. The National Institutes of Health recommends that people manage the condition by maintaining a healthy diet and weight, not smoking, and engaging in physical activity.
Studies have previously identified foods that appear to improve cardiovascular health including broccoli, pulses, fish, and spinach.
Now, Ana Rodriguez-Mateos and team have found that blueberries may also reduce the risk of heart disease due to their antioxidant content.
For the study, the team recruited 40 healthy participants who were randomly assigned to one of two groups. One group consumed a daily drink that contained 200g of blueberries while the other group consumed a control drink that did not contain blueberries.
The researchers measured the participants’ blood pressure and flow-mediated dilation (FMD) of the brachial artery, a major blood vessel found in the upper arm. The FMD test shows how much the artery dilates as blood flow increases and is a standard indicator of cardiovascular disease risk.
Next, the team compared drinking the blueberries with drinking a solution that contained purified anthocyanins or a control drink with a vitamin, mineral and fiber content similar to that found in blueberries.
As reported in The Journals of Gerontology, the researchers saw beneficial effects on blood vessel function just two hours after participants had consumed the blueberry drinks. Furthermore, over the course of one month, blood pressure in the blueberry drinking group fell by 5mmHg - a reduction comparable to the effects of anti-hypertensive medication.
The study also found that participants who consumed the drink with purified anthocyanins had improved endothelial function (as measured by FDM), while participants who consumed the control drink saw no such benefit.
"The effects were similar to those of blueberries containing similar amounts of anthocyanins, while control drinks containing fiber, minerals, or vitamins had no significant effect,” say the researchers.
Rodriguez-Mateos says the findings suggest that most of the health benefits can be attributed to anthocyanins.
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 [percent].”
Dr. Ana Maria Rodriguez Mateos, First Author