Broccoli is one of America’s favourite vegetables, which is great for our health - but only if we prepare it right. A common method of preparation is boiling. This process is notorious for leeching water-soluble vitamins, like Vitamin C and B, from vegetables, including broccoli.
But there’s more to this story that researchers have only just begun to discover. It turns out, the nutritional damage from boiling goes deeper than just water-soluble vitamins.
It hinders the body’s ability to absorb a class of compounds called glucosinolates, which a growing body of scientific research suggests could play a role in reducing the risk of lung and colorectal cancer.
Broccoli, supplements, and boiling
In a 2011 paper, researchers compared the level of certain cancer-fighting glucosinolates in humans who ate broccoli versus those who took broccoli supplements, made from broccoli sprout extract.
They discovered that the vegetable contains a key protein that helps our bodies break glucosinolates down for absorption while supplements lack this protein.
The result was that subjects who took supplements had up to eight times fewer glucosinolates in their blood and urine than those who ate the vegetable.
Moreover, the lead researcher of the study said that intensive cooking, like boiling, severely reduces the level of this enzyme in broccoli, so you get about as much nutrition from boiled broccoli as you do from broccoli supplements, which isn’t much.
Luckily, there is a way to combat the disadvantages of boiling: preserve the boiling water for later consumption.
Broccoli water (but there's a better way)
Broccoli water isn’t a new concept. In fact, the 1999 Harvard Medical School Family Health Guide suggests that you store broccoli water to later use in soups, sauces, or even gravy, LiveStrong reported.
One concern with broccoli water, however, is pesticides. In addition to leeching nutrients from broccoli, boiling water can also absorb pesticides that farmers use to avoid rot, weeds, and insects during the growing process. One way to avoid pesticides is to buy organic.
However, if you want to avoid the extra cost of organic produce, just steam your broccoli instead, said Guy Crosby, who teaches a food science course at Harvard School of Public Health and is the editor for America’s Test Kitchen.
Get the most out of your broccoli by steaming it
Crosby called preserving broccoli water from non-organic broccoli a "balancing act".
"If you’re concerned about the level of pesticides - some of them are water soluble and will be separated out in the cooking water, which would offset consuming the cooking water for the nutrients that are leeched out, so it’s a balancing act," Crosby told Business Insider.
The bottom line: Ditch the acrobatics and just steam your vegetables. It will benefit you in the long run.
In a paper published last November, Crosby and his colleague at Harvard, Adriana D.T. Fabbri, reviewed the literature on how different cooking methods affected the nutritional value of certain legumes and vegetables, including broccoli. They reported that:
"The total content of glucosinolates of fresh broccoli increased by steaming methods," the two stated in their paper adding that "Steam cooking: best procedure to preserve and enhance nutritional quality of fresh broccoli."
There you have it: If you want to get the most out of your broccoli, just steam it.
This article was originally published by Business Insider.
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