July 8th is National Blueberry Day, and out of respect for this tasty fruit today’s post will review a study which examined the effects of wild blueberry juice in a group of adult women at high risk for diabetes mellitus type 2.
Both wild and cultivated blueberries are native to North America. Depending on altitude, latitude and weather the peak of the blueberry crop can vary from May to August. In the US there are many blueberry festivals which celebrate this delicious fruit. In places like Bethlehem PA, Burgaw NC and South Haven MI, among many others, blueberry lovers gather to celebrate.
The skins of the blueberries contain anthocyanins, which have anti-oxidant properties. Wild blueberries have one of the highest levels of anti-oxidants among fruits and vegetables. In the U.S., Maine is the largest producer of lowbush or wild blueberries, and produces over 100 million pounds annually.
A group from Canada and the U.S. performed a study examining the effects of wild blueberry juice on various cardiometabolic markers. The study population had at least two risk factors for type 2 diabetes, and thus were higher risk.
The study design was a randomized trial, with a placebo control. The subjects drank 240 ml of juice made from lowbush (wild) blueberries, while the control group drank a placebo beverage which was color and flavor matched to the blueberry juice. The blueberries were harvested from Prince Edward Island, Canada. Participants drank the blueberry juice daily for a week, followed by an eight day washout period. Following that workout period, the study group became the control group and vice versa.
Several cardiometabolic markers were monitored during the course of the study, such as serum cholesterol, HDL, LDL, triglycerides, glucose, endothelial function, c-reactive protein, serum amyloid, among others. Vital signs included blood pressure were also monitored.
19 participants, all women, completed the study. The researchers discovered that while the wild blueberry juice did not significantly change cardiometabolic markers, it did lower systolic blood pressure 4.8 mm Hg (4%) compared to the placebo group. While a 4.8 mm Hg reduction in systolic blood pressure may not sound substantial, it is estimated that a reduction of only 3 mm Hg may reduce mortality from heart disease and stroke by 5-8%.
Drinking the blueberry juice for only 7 days was probably not long enough to effect any significant change on metabolic markers. A longer study seems reasonable given the promising results of this study. This does appear to be a low-risk way to improve one’s health.
“The smallest seed of faith is better than the largest fruit of happiness.”– Henry David Thoreau
(Source- BMC Nutrition 2017 3:45)
This blog is a review of published medical and scientific literature, and should only be used for informational purposes. It does not constitute medical or health advice, nor does it create a physician-patient relationship with anyone. Discuss any health concerns with your personal physician.