Heart-shaped leaves and a peppery punch make watercress a foodie favorite in salads, sandwiches and sautes. And recently, this leafy green won the World Cup of the fruit and vegetable world, running off with top ranking for its nutritional wallop.

In a new report from New Jersey's William Patterson College, this underappreciated green and nine others nabbed the Top 10 spots among 41 powerhouse fruits and vegetables. That's because of their ratio of nutrients (particularly vitamins C and K, iron, fiber, niacin, folate, riboflavin, other B vitamins and other phytochemicals) to calories; clearly, they all deliver more bang for your bite.

With summertime gardens and farmers' markets in full swing, there's no better time to say, "Move over, iceberg, and hello, wild and wonderful watercress," plus (Nos. 2-10) Chinese cabbage, chard, beet greens, spinach, chicory, leaf lettuce, parsley, romaine lettuce and collard greens. Adding them (and any other green you love, like arugula or kale) to your diet helps you achieve a younger RealAge.

You'll also lower your risk for diabetes. In one study, eating just 11/2 servings a day (the amount in a small salad) slashed risk for Type 2 diabetes by 14 percent.

Seems the greens' sugar-taming fiber, the fact that they're low-calorie but filling, and the magnesium and smidge of the good fat (alpha linolenic acid) they contain may help with healthy blood-sugar processing.

You'll have a healthier heart. Leafy greens contribute mightily to the power of a veggie-rich diet to lower heart attack and stroke risk by a whopping 30 percent. One reason? Greens like spinach deliver a big dose of lutein, a chemical that revs up your cell's antioxidant defenses to cool inflammation and keep arteries clean and flexible.

You'll boost your cancer protection. Lots of leafy greens are members of the cruciferous family, which contain a unique group of sulfur compounds proven to help reduce risk for cancers of the mouth, throat, larynx, esophagus and stomach.

You'll help protect your eyes. Like microscopic sunglasses, lutein and zeaxanthin - the phytochemicals found in kale, spinach and collard greens - help protect cells in your eyes from the sun's damaging ultraviolet rays. This can lower your risk for age-related vision robbers like cataracts and age-related macular degeneration.

You'll boost brain power. Folate, a B vitamin found in leafy greens (and some other produce), is famous for helping moms-to-be deliver healthier babies and prevent brain defects. Turns out folate keeps adult brains tuned-up, too.

Ready to dig in? Here are some easy ways to dish the green:

Put salad on your daily to-do list. A big bowl of greens - we like mixing baby spinach, kale and spicy arugula with romaine and other lettuces - is a great way to get your daily quota. It counts as several veggie servings (one of Dr. Mike's secrets for getting nine a day!), is easy to toss together (wash right before use) and tastes great.

Add good fats to your bowl with olive oil vinaigrette, plus a scattering of nuts, especially walnuts (they have the most omega-3s), seeds and some avocado. Those fats boost absorption of nutrients. Make salad your choice for late-night noshing, too.

Sneak powerhouse greens into unexpected places. Put arugula or spinach on your sandwich; try a bed of lightly sauteed greens underneath grilled salmon, chicken or veggies; and add a couple of handfuls of baby spinach or kale to soups, stews, chili or other veggie side dishes.

Try something new. Love iceberg lettuce? Give mixed greens a try. If you eat a lot of spinach, check out kale (we love tender baby kale). Into kale already? Try using assertively flavored mustard, collard or turnip greens instead.

Drink up. Make an easy green drink by whirling apple slices, cucumber and kale or spinach (watercress is good too!) in your blender. Or make it fancy by adding celery, carrots, fresh mint, and one quarter of a fresh orange, lemon, lime and pineapple - a Dr. Oz favorite.

Mehmet Oz, M.D. is host of "The Dr. Oz Show," and Mike Roizen, M.D. is Chief Wellness Officer and Chair of Wellness Institute at Cleveland Clinic. To live your healthiest, tune into "The Dr. Oz Show" or visit www.sharecare.com.