Broccoli is one of the healthiest vegetables out there, containing many essential vitamins and minerals and significantly reducing your risk of developing cancers.
New research shows that people who don't cook it in the right way could be wasting their time.
Scientists found broccoli loses its cancer-fighting properties when it is boiled or microwaved.
The researchers, who presented their findings at the American Institute for Cancer Research Annual Research Conference, found the best way to cook the vegetable is to steam it for up to five minutes. They say steaming it until it turns a bright green colour can enhance its cancer-fighting compounds.

Researchers have long been writing about the health benefits of broccoli, particularly one of its ingredients - sulforphane, which is thought to have anti-inflammatory and anti-cancer qualities. The authors warn that depending on broccoli powder supplements alone will not have anywhere near the same benefits, and neither will overcooking the vegetable. Researchers found boiling and microwaving broccoli, even for just one minute, destroys myrosinase, a key enzyme in the formation of sulforaphane. In contrast, they also discovered that steaming it for up to five minutes is the best way to retain the enzyme. "Past food processing has tended to focus on improving taste, visuals and microbiological safety," said Dr Elizabeth Jeffery, a researcher at the University of Illinois at Urbana-Champaign. "Now our task is to go further. Processing can ensure that the bioactives – the cancer protective compounds – arrive in your digestive system in a form the body can use."

Study participants ate a broccoli supplement with no active myrosinase. When some of them ate a second food with myrosinase, their blood and urine levels of sulforaphane were significantly higher than those who did not eat the second food with myrosinase.
Jeffery also found that if you do eat well-cooked broccoli, you can still get sulforaphane to form by adding raw foods containing myrosinase to your meal.
"Mustard, radish, arugula, wasabi and other uncooked cruciferous vegetables, such as coleslaw, all contain myrosinase, and we’ve seen this can restore the formation of sulforaphane," Dr Jeffery said.

In another sudy, the same researchers also found a simple way to preserve broccoli’s cancer-fighting properties when industrially frozen.
Before broccoli is frozen and packaged, it is standard industry practice to first heat the vegetable to 86° C (187° F) in a process known as blanching to inactivate enzymes that can affect its color, taste and smell over its 18-month shelf life. Also in this case Elizabeth Jeffery and her team found that the process destroys the enzyme myrosinase. So the team did a test heating the vegetable to a slightly lower temperature of 76° C (169° F) and found that 82% of the enzyme myrosinase was preserved without affecting the frozen vegetable’s safety or quality.
Although the researchers hope food processors will adopt the lower temperature process, Jeffery says that until they do, consumers can help boost frozen broccoli’s health benefits by sprinkling it with a related cruciferous vegetable containing myrosinase before cooking.

"As we're learning, food processing isn't just what happens to food before it reaches the grocery shelves," AICR associate director of nutrition programs Alice Bender said in the news release. "This research highlights that what you do in your kitchen can make those fruits and vegetables on your plate even more cancer-protective."

So before preparing your meals, remind also that previous research has found:

crushing or chopping garlic and then waiting 10 to 15 minutes before exposing it to heat allows its inactive compounds to convert into the active, protective phytochemical known as allicin;
cooking tomatoes and other foods that contain lycopene allows our body to more easily absorb the beneficial phytochemical;
boiling vegetables for a long time means you lose water-soluble vitamins, such as vitamin C, folate and niacin that leach into the water.

Here's an easy, deliciuos recipe to enjoy all the benefits of broccoli

Steamed broccoli with mustard sauce

Ingredients - yield 3 servings

1 1/2 pounds broccoli
2 tablespoons butter, softened
4 teaspoons lemon juice
2 teaspoons coarse-grained mustard

Preparation

1. Trim the thick stems from the broccoli. Cut flowerets into small portions.

2. Steam over boiling water for about 5 minutes, until crisptender.

3. Meanwhile, place butter, lemon juice and mustard in serving dish and mix thoroughly. When broccoli is cooked, drain and place in dish. Mix well to coat with sauce and serve.

You may be interested in reading also "Stock your fridge with greens that boost your immune system and be protected from cancer"

Sources: http://www.medicalnewstoday.com/, http://www.dailymail.co.uk/, http://consumer.healthday.com/, http://www.nytimes.com/recipes/http://consumer.healthday.com/