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 fruit 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.

Seasonal fruits and vegetables cost less than produce available at other times of year, so they can help stretch your food dollars. If you pick -- or even grow -- your own, you can also save money.

What many people don't know is that it isn't only fresh produce that provides health benefits. Studies show that canned, dried and frozen fruit and vegetables have nearly all the same attributes as fresh -- provided that you choose products that don't have added sugar or extra salt.

Listen to your mother

Eating more fruit 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 fruit 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 fruit 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 fruit, from jicama to litchi nuts, contain allicin. It helps control blood pressure and cholesterol and may bolster immunity.

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 might have antimicrobial activity. In April scientists reported that substances extracted from broccoli and other cruciferous vegetables thwarted the bacteria that causes stomach ulcers as well as 23 out of 28 other common microbes and fungi -- at least in the laboratory. There's also evidence that eating cruciferous vegetables might help counteract the suspected cancer-causing chemicals that occur in grilled food.

Dietary supplement makers have tried to duplicate the health effects of fruit and vegetables without success. In one large Scandinavian study, smokers who took supplements with beta-carotene actually had an increased risk of lung cancer compared with those who didn't take the pills. To date, there have been no reported harmful effects of consuming any of these substances in food.

Meet daily requirements

What makes food better? Scientists believe it comes down to synergy -- reactions that take place in the food between phytonutrients and vitamins and minerals.

That's why it's key to meet the recommended daily intake for fruit and vegetables. Studies suggest that just 25 percent of adults and children in the United States eat enough fruit daily. Only 13 percent get enough vegetables.

How much do you need? Forget the old "five-a-day" advice. That was retired in 2005 when the U.S. Dietary Guidelines were updated. Current recommendations are for most adults to eat about 2 cups of fruit (roughly equal to two pieces) and about 2.5 cups of vegetables daily.

The message is simple: If you're looking for flavorful food that is worth its weight in nutritional benefits, reach for fruit and vegetables. Or perhaps this Middle Eastern saying puts it best: "A melon for ecstasy!"

Subscribe to the free Lean Plate Club e-mail newsletter at Sally Squires is a writer for the Washington Post.