What’s the healthiest food you know of? If you're thinking broccoli, you wouldn’t be wrong exactly — but you wouldn’t be right, either. There’s more and more evidence that leafy greens are the real superfoods of the veggie world.

For example, in a study published by the Centers for Disease Control and Prevention (CDC) looking at the nutrient density of 41 powerhouse fruits and vegetables — which the CDC defines as “foods most strongly associated with reduced chronic disease risk” — with the exception of chives, the top 16 fell into the green leafy or cruciferous vegetable families.

“If a drug could do what these vegetables could do, it would be the most successful drug in the history of medicine,” says Joel Fuhrman, MD, author of “Eat to Live” and “Eat to Live Cookbook.”

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The best greens of the bunch

Here are the CDC's top 16 foods, listed in order, starting with the most nutrient-dense:

  1. watercress
  2. Chinese cabbage
  3. chard
  4. beet greens
  5. spinach
  6. chicory
  7. leaf lettuce
  8. parsley
  9. romaine lettuce
  10. collard greens
  11. turnip greens
  12. mustard greens
  13. endive
  14. chives
  15. kale
  16. dandelion greens

Who’d have guessed that romaine lettuce was more nutrient dense than kale? Or that watercress, parsley and endive all rank higher than broccoli (17 on the list), Brussels sprouts (19), cauliflower (22) and carrots (24)?

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Simply adding more of these foods to your daily diet will bump up your nutrient intake. But you can reap even more of the health-preserving perks of greens by following these tips for prepping and eating them.

1. Gobble down as many greens as you want — you can't overdo it

"Everything in moderation," goes conventional wisdom. But when it comes to greens, research suggests the more you eat, the more benefits you’ll realize.

For example, a Chinese study of 134,000 people found that the more cruciferous vegetables they ate, the more they were protected against heart disease and even early death. “The risk of death went down in a dose-dependent fashion,” Fuhrman says. He suggests thinking of greens as a central part of the diet, and having something green with every meal.

There are a couple of exceptions. If you suffer from chronic kidney stones, “it’s prudent to limit your consumption of raw spinach and Swiss chard, rhubarb and parsley to less than a third of total green intake,” Fuhrman says. Talk to your doctor about the wisdom of including these veggies in your diet if you're prone to kidney stones. 

Also, you may have heard that dark green veggies are a no-no for anyone taking the blood thinner warfarin (brand name Coumadin). This isn’t exactly true — it's a consistent intake of vitamin K you need, and therefore a consistent intake of greens rich in the vitamin. If this becomes a problem for you, ask your doctor about other blood thinners that don't pose the vitamin K problem.

Another misunderstanding about greens: Some people believe you should avoid greens if you have hypothyroidism. “It’s an Internet myth,” Fuhrman says. The myth, he says, is based on a study done using excessively high doses on animals. “In fact, greens may help to prevent this condition."

2. Eat your greens raw and cooked

Raw green veggies contain an enzyme, myrosinase, that enables cancer-preventing compounds called isothiocyanates to form. When greens are cooked, however, myrosinase breaks down.

On the other hand, you’ll likely get a more concentrated hit of other nutrients from cooked greens because the leaves take up less space when wilted, making it easier to eat more at one time.

Fuhrman recommends balancing the raw and the cooked this way: “Eat some raw cruciferous greens every day, and eat some raw and some cooked in the same meal.” Cruciferous veggies include arugula, bok choy, broccoli, Brussels sprouts, cabbage, collard greens and kale, according to the National Cancer Institute.

3. Chew on this: The longer you munch on greens, the more you benefit

Myrosinase is released through pulverization of the plant cell walls. The longer you chew raw greens before you swallow them, the greater the benefits. 

For the same reason chewing is beneficial, so is pureeing. Make pesto from spinach or parsley, or add a healthy handful to the food processor when preparing the classic basil kind.

Juicing raw veggies also will bring out their myrosinase. Juicing eliminates the also-good-for-you fiber, but if you’re looking for ways to sneak in more greens, juices are worthwhile.

If you want to include raw veggies in soups or other heated foods, Fuhrman recommends blending them before adding them. This will allow the chemical reaction to occur before the heat destroys the enzyme.

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4. Add healthy fats to unlock nutrients

Certain fat-soluble nutrients in greens, such as antioxidants known as carotenoids, don’t “unlock” unless consumed with fat. “When you eat your green veggies with oil, nuts and seeds, the cancer-preventing compounds are maximized,” says Fuhrman. He recommends making dressings with these ingredients. The nuts you blend in with greens for pesto will serve the same purpose.

Research also has found that topping a salad of raw greens and veggies with eggs improves the absorption of carotenoids, including beta-carotene, lutein, zeaxanthin and lycopene.

5. Count certain greens toward your total protein

Popeye was right on one count — spinach is a mighty muscle builder. But the Sailorman was wrong on another: He attributed spinach’s biceps-boosting power to iron. According to the U.S. Department of Agriculture, an average bunch of spinach has 9 grams of protein. That’s not nearly as much protein as beef, poultry, pork or seafood has, but it's more than you’ll get from an egg, a slice of Swiss cheese or a glass of 2 percent milk or soy milk, which all have around 8 grams of protein each. For vegetarians and vegans who rely on non-animal sources of protein, spinach can contribute quite a lot. Other green foods that are relatively high in protein include peas, kale, Brussels sprouts and broccoli.

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Amy Roberts is a certified personal trainer. She writes about fitness, health and a variety of other topics for many well-known publications.