At the Friedman School of Nutrition Science and Policy at Tufts University, you can tell it is blueberry season by the bowls of local blueberries popping up on desks across campus. So, this month, we’ve gathered a bushel of our subscribers’ questions and experts’ answers about the benefits of these antioxidant rich berries.
Q. It’s not always convenient to eat fresh blueberries. How do frozen and dried blueberries compare in nutrition and brain benefits?
A. Barbara Shukitt-Hale, PhD, of Tufts’ HNRCA Neuroscience and Aging Laboratory, has researched the brain benefits of blueberries and their anthocyanin compounds. She says, “Frozen berries do not lose their potency. For dried blueberries it depends on how they were dried. High temperatures cause berries to release more anthocyanins, but then they degrade faster.” Freeze drying, which does not require heating the berries, preserves their anthocyanin content; in fact, some of the studies on blueberries and cognition have used a powder made from freeze-dried fruit.
Q. Do blackberries have similar brain benefits from polyphenols as seen in blueberries?
A. “Increased dietary intake of berry fruit, in particular, has a positive impact on human health, performance, and disease,” says Barbara Shukitt-Hale, PhD, of Tufts’ HNRCA Neuroscience and Aging Laboratory. Shukitt-Hale and colleagues, who have shown cognitive benefits from blueberry consumption, performed a similar experiment with blackberry extracts. Their study, published in Nutritional Neuroscience, tested a 2% blackberry-supplemented diet for its effectiveness in reversing age-related deficits in behavioral and neuron function when fed to aged rats for eight weeks. “The results showed that the blackberry diet improved motor performance on three tasks which rely on balance and coordination.… Results for a water maze showed that the blackberry-fed rats had significantly greater working, or short-term, memory performance than the control rats. These data support our previous investigations in which we have seen improved motor and cognitive performance in aged rats after supplementation with other berry fruits.”
Q. For years I’ve daily eaten blueberries and a few walnuts with 1% milk. But recently I was told that milk neutralizes the antioxidant benefit of the blueberries. Is this true, and if so does milk similarly affect other berries and antioxidant-rich foods? Would yogurt do the same thing?
A. Jeffrey Blumberg, PhD, director of Tufts’ HNRCA Antioxidants Research Laboratory, replies: “Some research studies do suggest that the protein in milk binds to flavonoids, a large class of dietary antioxidants including the anthocyanins found in blueberries and other colorful berry fruit. However, these data have been generated from small studies and the results are not entirely consistent and may be confounded by other dietary components of a snack or meal. While yogurt has not been tested in these studies, it does, of course, contain the same type of protein as milk. It is useful to keep in mind that many of the nutrients in foods interact with one another, sometimes in additive and sometimes in negative ways, but if you eat a healthful diet, you will consume—and absorb—plenty of these beneficial compounds.”
Have a question for our Tufts Experts? While having your question answered by Tuft’s University and HNRCA specialists is a subscriber exclusive benefit, anyone can tweet their food and nutrition questions to @NutritionLetter and our resident RDN will select a question to answer on Twitter every Friday!
These questions and answers have been adapted from the Tufts Health & Nutrition Letter, a publication of the Friedman School of Nutrition Science & Policy at Tufts University: Editor-in-Chief, Dariush Mozaffarian, MD, DrPH, and Executive Editor, Alice H Lichtenstein, DSc. It is written with your needs in mind but is not a substitute for consulting with your physician or other health care providers. The publisher and authors are not responsible for any adverse effects or consequences resulting from the use of the suggestions, products or procedures that appear in this magazine. All matters regarding your health should be supervised by a licensed health care physician.
The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy is the only graduate school of nutrition in the United States. The mission of the school is to generate trusted science, educate future leaders, and produce real world impact.