There are lots of reasons to love blueberries. A good source of vitamin C, potassium and fiber, blueberries are delicious on their own or with cereal, yogurt, salads and other foods. Plus, they’re a top source of polyphenols (notably anthocyanins, which give them their blue color) and other antioxidants.
But does eating blueberries with milk negate the antioxidants? That’s what a small Italian study last year found. Here’s the scoop on that research, plus answers to other questions you may have about blueberries.
In the Italian study, published in Free Radical Biology and Medicine, people who ate blueberries with milk ended up with lower blood levels of polyphenols, compared to when they consumed the berries with water. The study also found that whole milk decreased antioxidants the most, suggesting that the fat in milk may be partly to blame.
Keep in mind, the study was done under laboratory conditions and may not reflect what happens in real life. In any case, not all studies have shown an inhibitory effect of milk on antioxidants. Moreover, many substances in foods interact with others, for better or worse, and if you eat a healthful diet all around, you’ll get—and absorb—a variety of beneficial substances.
Does cooking blueberries affect their antioxidants?
Apparently not. The substances are fairly heat-stable. In a 2009 study, for instance, blueberries that were microwaved, simmered, pan-fried or baked showed no significant loss in antioxidants. In fact, pan-frying for a short time actually increased antioxidant activity, possibly because it breaks down cell walls, releasing the antioxidants. (That’s what happens when carrots are cooked, too).
What about freezing or drying them?
A study from Australia in 2004 found that blueberries frozen for up to three months still had high levels of antioxidants. Dried blueberries also showed as much antioxidant activity as fresh ones.
Do organic blueberries have more antioxidants?
They have more anthocyanins and other polyphenols and greater antioxidant activity than conventionally grown blueberries, according to a 2008 United States Department of Agriculture (USDA) study. But there was also a lot of variation from farm to farm, no matter how the berries were grown. From a health perspective, it makes little difference whether you choose organic or conventional berries. Still, blueberries rank high in pesticide residues, and if you want to limit your exposure, buying organic is an option.
What are blueberries’ health benefits?
They have blood sugar-lowering, anti-inflammatory, neuroprotective, anti-cancer and other beneficial effects—at least in lab studies. Many of the supposed benefits of blueberries are attributed to their anthocyanins, which are also found in blackberries, black currants, red wine, grape juice and other red/blue/purple foods. Studies in people are few, though.
In one, published in the Journal of Nutrition last year, obese people with cardiovascular risk factors who drank a blueberry beverage every day for eight weeks showed a significant drop in blood pressure and a decrease in markers of oxidative stress. The study used the equivalent of two cups of blueberries a day. And in a small study published in the Journal of Agricultural and Food Chemistry, older people with early memory decline who drank a lot of blueberry juice (15 to 21 ounces a day) for 12 weeks showed improvements on memory tests.
Bottom line: Blueberries are super in terms of their antioxidants and potential health benefits. And they cost less than fruits such as goji and açaí, which are hyped as superfruits. Frozen, dried or canned blueberries are good options when berries are not in season, or just for convenience. Products like jams and pie fillings, though, often have lots of added sugar.