Chew on this: 04/14

Banishing the blues with blueberries

By Jayne Powers

A change of seasons often signals a change in what we eat.

Springtime ushers in a time to look forward to eating a variety of fruits and vegetables that become ripe in the summer and fall.

One fruit to make room for this season and all year round is blueberries, which reach their peak in June and July, and remain on supermarket shelves during other times of the year, thanks to imports from South America.

Increasingly, the buzz about blueberries continues to praise the health benefits of this dynamic little blue fruit, which is indigenous to North America.

The latest research links blueberry consumption to improved blood pressure, and more than three-dozen clinical trials about the potential health benefits of blueberries are now under way.

These studies are testing whether blueberries promote a healthier body, from vision to arterial function to improved blood-sugar regulation. Researchers also continue to investigate how eating blueberries delays dementia and aging.

If only blueberries weren’t so expensive and seasonal! Fortunately, frozen blueberries are available year-round and cost a bit less. They also retain most of their anthocyanin pigments, a chemical compound responsible not only for the blue color of blueberries but the red and purple colors of other fruits and many vegetables, cereal grains and flowers.

While plant physiologists and botanists have long studied anthocyanin pigments, interest in them today has intensified because of their potential health benefits as a dietary antioxidant, which is a chemical property shown to fight free radicals that damage cells as well as DNA.

This interest began in the 1990s and continues today. The latest study looked at whether eating blueberries affected blood pressure. The study used a freeze-dried blueberry powder (about 1 cup of fresh blueberries) and a placebo powder to determine blueberries’ blood-pressure effects.

The eight-week clinical trial, published in the Journal of the Academy of Nutrition and Dietetics involved 48 postmenopausal women in the early stages of hypertension. They were randomly assigned either the blueberry or placebo powder.

The participants who were randomly assigned to the blueberry powder showed improved blood pressure. Their average systolic blood pressure (the top number) declined 5.1 percent while diastolic pressure dropped 6.3 percent.

“These findings suggest that blueberries may prevent the progression to full-blown hypertension,” according to the researchers’ comments. “The changes in blood pressure noted in this study are of clinical significance, as they demonstrate that blood pressure can be favorably altered by the addition of a single dietary component.”

This favorable news adds to other positive research findings pertaining to cardiovascular health, namely the positive affect blueberries have on LDL (bad cholesterol). Other research has focused on whether berries, such as blueberries, are good for brain health.

The findings in this area point to good news. One clinical trial showed women who ate two or more half-cup servings of blueberries or strawberries per week delayed the aging of their mental faculties by two-and-a-half years.

The compounds found in blueberries were found to be responsible for this delay in aging. These compounds enable aging neurons in the brain to communicate again.

For diabetics, there is also good news. While blueberries aren’t the lowest ranking berry on the Glycemic Index, a tool used by diabetics to manage blood sugar, research suggests eating blueberries help control blood sugar.

According to a recent study, glucose tolerance improved in mice that ate a diet supplemented with blueberries. Research on humans is ongoing.

In another study, human participants were randomly given a total of 45 grams of blueberry powder in a smoothie for breakfast and dinner or a placebo-powder smoothie that contained comparable macronutrients. The results of the study have yet to be published, however.

Although the evidence is less definitive for fighting cancer, the American Institute for Cancer Research lists blueberries as a cancer-fighting food on its website (

Blueberries are also an excellent source of Vitamins C and K, and manganese as well as a good source of fiber.

How to buy blueberries

Look for firm berries that have a uniform color, and don’t skip over blueberries with a whitish bloom. This natural coating protects their skins.

The best way to store blueberries is in a covered container in your refrigerator. Wash them right before eating. If you wash and then store them in your refrigerator, mold could develop if they’re not completely dry. That goes for any vegetable or fruit.

Perhaps a bigger conundrum is whether to buy organic. Remember that buying organic doesn’t mean the berries will be more nutritious. It means that organic farming limits their pesticide exposure. Blueberries didn’t make the Environmental Working Group’s “Dirty Dozen” list, but they are close to the threshold at No. 14. If you buy organic, look for the USDA organic certification label.

Jayne Powers, MA, is a certified nutritionist and personal fitness trainer based in Washington, DC. Her column, Chew on This, speaks from the science of the current state of knowledge about all facets of nutrition. Find her online at, or email your fitness questions to

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Jayne Powers, MA, is a certified nutritionist and personal fitness trainer based in Washington, DC. Her column, Chew on This, speaks from the science of the current state of knowledge about all facets of nutrition. Find her online at

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