WASHINGTON—Imagine a drug that could whittle your waistline, control your blood pressure, protect your heart, strengthen your bones, cut the risk of stroke and possibly help you sidestep some types of cancer. And what if this drug was also easy to obtain, pleasurable to swallow and inexpensive?

It would be hard to beat, wouldn’t it?

There’s no pill with those benefits, but there are foods that hit those high nutritional notes. I’m talking, of course, about fruits and vegetables.

Scientists are just beginning to fully understand the power of produce. And the start of summer provides a great opportunity to expand your nutritional horizons by sampling the fruits and vegetables that peak now and in coming months.

Common-sense advice

Eating more fruits and vegetables is the kind of common-sense advice that mothers have dished out for generations. Now, 21st-century scientists are beginning to fathom why fruits and vegetables provide so many health benefits.

It has to do with an array of essential vitamins, minerals, fiber and phytonutrients—plant-based substances with tongue-twisting names such as anthocyanins and lycopene. Don’t worry about pronouncing them. Just know that they’re good for you and are found in pink and red produce, including pomegranates, red cabbage, cherries, red peppers, watermelon and red grapes. They appear to help reduce the risk of some tumors, including prostate cancer.

That’s just for starters.

Green produce, from avocado, pears and limes to okra, green beans and zucchini, is rich in carotenoids. These substances help preserve vision by protecting the retina and gobble up free radicals to help thwart cancer and aging.

Yellow- and orange-hued fruits and vegetables are rich in beta-carotene—which is converted by the body to vitamin A. It boosts immunity and protects vision. Count apricots, bananas, papayas, peaches, carrots and butternut squash among this group, which also packs other nutrients. Pineapple, for example, has bromelain, an enzyme that aids in digestion and reduces bloating.

White vegetables and fruits—from jicama to lychee nuts—contain allicin, which helps control blood pressure and cholesterol and may bolster immunity.

Superstars

But the superstars seem to be cruciferous vegetables: broccoli, Brussels sprouts, cabbage and cauliflower as well as arugula, kale, kohlrabi, mustard, rutabaga, turnips, bok choy, horse radish, wasabi and watercress.

These vegetables contain potent substances that seem to protect against cancer and may have antimicrobial activity. In April, scientists reported that substances extracted from broccoli and other cruciferous vegetables thwarted the bacteria that cause stomach ulcers as well as 23 out of 28 other cotmon microbes and fungi—at least in the laboratory. There’s also evidence that eating cruciferous vegetables may help counteract the suspected cancer-causing chemicals that occur in grilled food.