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Little powerhouses of nutrition

DEAR DOCTOR K: Berry season is here again, and I keep hearing that berries are healthy. What’s in them that makes them so good for you?

DEAR READER: Berries are perhaps the easiest way to follow the fruit part of the “eat more fruit and vegetables” advice you hear all the time. Berries naturally come in bite-sized portions. They’re sweet but have a nice low calorie count, partly because they contain a lot of water. If you don’t need to watch your calories – yes, there are people who are born thin – you can “pig out” on them. (Just don’t sprinkle much sugar on them.)

Berries contain vitamins (C and a little bit of E, because of the seeds) and some lesser-known nutrients. But they also, somewhat surprisingly, contain a fair amount of fiber. A cup of raspberries contains 8 grams of fiber, which is more fiber than you’ll find in a serving of oatmeal.

But what makes berries stand out nutritionally (and visually) are substances called anthocyanins. These substances give berries their vivid red, blue and purplish colors. Anthocyanins are antioxidants, which keep oxygen ions and other unstable molecules from damaging DNA, messing with cells’ energy-making machinery, stirring up inflammation in the body and having a variety of other harmful effects.

Anthocyanins are concentrated in the skin of berries (as well as other fruits). In general, the more intense the color, the higher the anthocyanin content. So blueberries and blackberries usually contain more anthocyanins than strawberries or raspberries. And wild berries have more antioxidants than their larger, paler, domesticated relations. Raspberries also contain a substance called ellagitannin, which imparts flavor and has antioxidant properties that add to the effects of anthocyanins.

Be sure to wash your berries right before eating them. Berries can harbor viruses, bacteria and other pathogens that cause foodborne illnesses.

To send questions, go to, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.