Purple veggies show promising health benefits

Purple is not simply a popular trend in fashion. This color of royalty, dubbed the "new black" by fashionistas, is also the new black in food.

In produce aisles, at farmers markets and on restaurant menus, you can now find a growing array of heirloom and specialty vegetables with a distinctive purple hue: purple potatoes, tomatoes, carrots, beans, corn, asparagus, peppers, baby artichokes and cauliflower.

"I'm a huge fan of purple," said Chicago chef Rick Tramonto, who features purple potatoes and purple cauliflower on the menu at Tru restaurant. "I love the color and texture; there is more earth to it."

Beyond the pleasing appearance on the plate, the purple color is a cue for nutritional power.

The dark pigments responsible for the purplish tones are called anthocyanins, a type of phytonutrient, or plant compound, hailed for its potential disease-fighting benefits. Studies suggest anthocyanins may help reduce the risk of heart disease, diabetes and certain types of cancer. Some evidence indicates these purple pigments may protect our brain as we age.

Anthocyanins belong to the flavonoids family of plant compounds. They are among the most potent of all phytonutrients and have gained the attention of scientists worldwide.

"If I could only eat one color per day, it would be purple," said James Joseph, a neuroscientist at the USDA Human Nutrition Research Center on Aging at Tufts University and co-author of "The Color Code: A Revolutionary Eating Plan for Optimum Health."

The most concentrated natural sources of anthocyanins are blue and red fruits, including blackberries, blueberries, cranberries, cherries, Concord grapes and lesser known berries such as chokeberries, elderberries and bilberries.

Studies with these deeply hued fruits have shown promising health benefits, but scientists are investigating ways to boost the level of anthocyanins in commonly eaten foods to offer even greater health-promoting potential. Among the findings:

--Researchers in Great Britain used genes from snapdragons to generate higher production of anthocyanins in tomatoes, which resulted in intensely purple tomatoes with anthocyanins levels comparable to blackberries and blueberries.

--Anthocyanins from purple corn were the most potent in inhibiting the growth of colon cancer cells compared to the other vegetables and fruits evaluated by Ohio State University researchers.

Despite the hot trend and health-promoting potential of the color purple, an analysis by the Produce for Better Health Foundation found that only 3 percent of the fruits and vegetables consumed in the U.S. are from the purple or blue category.

With the growing interest in anthocyanins, you'll begin to see pills and products fortified with fruit extracts, but Joseph recommended sticking with the real thing.

"You're better off with the whole fruit or vegetable."

Get your purple on

You may not find the trendy purple-hued vegetables where you shop, but they are increasingly available during the summer at farmers markets, in seed catalogs and via online distributors of specialty produce. More commonly available purple vegetables include purple cabbage and purple kale. Even purple onions contain anthocyanins. You'll find the protective purple compounds in eggplant, but only if you eat the peel. Here are more ways to add purple to your plate:

--Sprinkle blueberries or blackberries on your morning cereal or oatmeal.

--Make coleslaw with shredded purple cabbage and purple carrots.

--Slice purple grapes and add to chicken salad or a tossed green salad.

--Add purple carrots and purple kale to a stir-fry.

Recipe

This recipe is adapted from a bread soup with beans and kale from "Outstanding in the Field: A Farm to Table Cookbook," by Jim Denevan. We've omitted the bread to cut down on the calories. If using canned beans, wait until the final step to add them.

Purple Kale and White Bean Soup

Makes: 8-10 servings

1 cup dried cannellini or other beans, or 1 can (14.2 ounces), drained, rinsed

1 1/2 teaspoons coarse salt

Freshly ground pepper

3 tablespoons extra-virgin olive oil plus more for serving

2 onions, halved, thinly sliced

3 ribs celery, finely chopped

2 carrots, finely chopped

1 dried red chile, chopped or 1/4 teaspoon crushed red pepper flakes

1 sprig fresh rosemary

1 tablespoon tomato paste

8 ounces purple kale, stems and ribs discarded, leaves chopped into 1-inch pieces

2 quarts chicken stock or low-sodium broth

Freshly grated parmesan or pecorino cheese

Pick over dried beans, discarding any stones; rinse. Place beans in a stockpot; cover with cold water by 2 inches. Let stand overnight; drain and rinse.

Place beans in a large stockpot; cover with cold water. Heat to a boil over high heat, skimming off any foam as it rises. Reduce the heat; simmer until beans are tender, about 1 1/2 hours. Stir in 1 teaspoon of the salt and pepper to taste. Set aside to cool.

Meanwhile, heat the 3 tablespoons oil in a Dutch oven over low heat; add the onions. Cook, stirring occasionally, until the onions are soft and translucent, about 10 minutes. Add the celery, carrots, chile and rosemary; season with 1/4 teaspoon of the salt and pepper to taste. Cook, stirring occasionally, until the vegetables soften and become fragrant, about 10 minutes. Add the tomato paste; stir to coat the vegetables. Cook until the tomato paste begins to caramelize, about 3 minutes.

Add kale and remaining 1/4 teaspoon of the salt and pepper to taste. Cook until kale has wilted a bit, 3 minutes. Add enough of the chicken stock to cover. Heat to a boil over medium-high heat. Reduce the heat to a simmer; cook until kale is tender, 15-20 minutes. Strain the beans; add them to the Dutch oven along with remaining stock (if using canned beans, add them now). Simmer 5-10 minutes. Remove rosemary sprig; discard. Serve with grated cheese and a drizzle of olive oil.

Nutrition information: Per serving: 145 calories, 32 percent of calories from fat, 5g fat, 1g saturated fat, 0mg cholesterol, 18g carbohydrates, 8g protein, 395mg sodium, 5g fiber.