If you want to maximize the cancer-fighting compounds in your diet, pay attention to how you process and prepare your food.
That’s right—food processing isn’t something that only happens in big food plants; it’s something you do in your kitchen every day. When it comes to food, we chop, press, juice, mash, steam, sauté, boil, bake, and more. These processing and preparation techniques do more than make food safe and tasty—they can also enhance or destroy the cancer-fighting compounds that naturally occur in many foods.
In fact, many foods contain components referred to as bioactives, which are cancer protective compounds. In order for these bioactives to do their job, they must arrive in your digestive system in a form that the body can use. The way you cook—or don’t cook—your food has everything to do with this process.
Steam Your Broccoli
Take broccoli, for example. Researchers have found that steaming broccoli for three to four minutes—until it turns bright green—will enhance its cancer fighting compounds. That’s because broccoli, like other cruciferous vegetables, is a good source of sulforaphane, which is a phytochemical with strong anti-cancer properties. The tricky thing about sulforaphane is that it relies on an enzyme called myrosinase in order to form. If the myrosinase is destroyed, sulforaphane cannot form.
Guess what destroys myrosinase? Some cooking techniques. In fact, researchers from the University of Illinois found that boiling or microwaving broccoli for one minute or less destroyed the majority of myrosinase. In contrast, they found that steaming broccoli for up to five minutes was the best way to retain the enzyme. They presented these results at the American Institute for Cancer Research (AICR) Annual Research Conference.[i]
Undoing the Damage
If you happen to overcook your broccoli, all is not lost. The same group of researchers found that you can mitigate the effects of overcooking, by adding raw food that contains myrosinase to your meals.[ii] This will help the sulforaphane to form. For example, two groups of people were given broccoli with no active myrosinase. One group ate a second food that contained myrosinase, and they had significantly higher levels of sulforaphane than the group that did not eat the second food.
The researchers said that mustard, radish, arugula, and other uncooked cruciferous vegetables contain myrosinase, and these foods can restore the formation of sulforaphane.
The Big Picture
Broccoli is just one example of the association between food preparation and cancer-fighting compounds. Research has consistently shown that food-processing techniques can enhance or destroy cancer-protective and other nutritional compounds. For example, boiling vegetables for a long time causes water-soluble vitamins (such as vitamin C and folate) to leach out of the vegetables and into the water, which usually gets dumped down the drain. On the opposite end of the spectrum, however, cooking tomatoes helps our bodies to more easily absorb a phytochemical called lycopene.
In general, less is more when it comes to food preparation, but tomatoes are an exception. Researchers continue to study how everyday food preparation techniques can help us retain the most nutritional value from our food.
[i] American Institute for Cancer Research, news release, Nov. 7, 2013. Available at:
[ii] Dosz EB, Jeffery EH. Modifying the processing and handling of frozen broccoli for increased sulforaphane formation. Journal of Food Science. 2013; 78(9): H1459-63.