While a cup of kale a day won't necessarily keep the oncologist away, experts agree that a daily diet with at least five servings of antioxidant-rich fruits and vegetables may help reduce your risk of cancer.
Antioxidants work by neutralizing the free radicals in our body, which are charged particles that cause DNA damage. Cancer is widely believed to be caused by genetic mutations driven by DNA damage. Clare McKindley, a dietitian at the M.D. Anderson Cancer Center in Houston, likens free radicals to fighting siblings. "The antioxidant would be the mom who comes in and says, 'Hey, quit poking your little sister.'"
McKindley says people should look for ways to make antioxidants part of their diets. She encourages people to make a serving of vegetables (generally 1 cup steamed or raw) the basis of their plate, and then build it from there. "Something I do if I go to an Italian restaurant is order a salad and lasagna and put a [small] square of lasagna on top of my salad. That way I also avoid salad dressing," she says. "Or at a Mexican restaurant, if bell peppers and carrots come with the meal, you can use those to dip into the salsa instead of chips. You're ultimately creating a safe behavior in a high-risk environment, and that builds confidence."
Variety is also key to an antioxidant-rich diet, says Walter Willett, a professor of epidemiology and nutrition at the Harvard School of Public Health, whose influential book Eat, Drink and Be Healthy, set the standard for healthy eating a decade ago. "None of these [fruits and veggies] are magical. I like to think of nutrition as an orchestra. You need variety and balance."
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Here are four fruits and veggies to eat with confidence this season:
Spinach. About half of Americans eat no leafy green vegetables, according to Willett. And that means spinach. "People either love it or hate it," he says. "If people are not spinach eaters, they are usually very low on green leafy vegetables." Spinach, along with spring greens including romaine lettuce and mustard greens, protects against cancers of the mouth, larynx, and pharynx. Spinach is also a good source of fiber. Cook it in a little olive oil: The fat allows some of spinach's micronutrients like vitamin K to be more easily absorbed by our bodies, Willett says. Raw spinach is a great base for salads, and toss in some strawberries or blueberries for a double dose of antioxidants. Just make sure the leaves are not wilted or damaged, says McKindley. "If you're eating things with mold on it, they are not going to be very cancer-protective."
Broccoli. The best-known member of the cruciferous family of vegetables, broccoli protects against colorectal and breast and bladder cancers. Broccoli is also a good source of fiber, folate, and potassium. Raw, it makes a nice complement to salads. Steamed is another good way to absorb broccoli's many nutrients. McKindley recommends starting with a cup of steamed broccoli on your plate, and then adding some mac and cheese. Or for a vegetarian pasta dish, sauté broccoli, mushrooms, and zucchini; accent the medley with pasta. Look for odor-free broccoli with bluish-green florets.
Strawberries. Toss a half-cup of strawberries into your morning cereal or oatmeal, or make a parfait with Greek yogurt and granola. You can also make fresh juice with a cup of strawberries, a few carrots, and an apple to get strawberries' direct nutrients like vitamin C. Apart from being loaded with vitamin C, strawberries are also rich in fiber, and blending them into a smoothie retains that, explains McKindley (unlike juicing, which retains strawberries' nutrients, but strips them of fiber). And fiber, in keeping us regular, indirectly protects the immune system, which helps prevent cancer. Strawberries protect against breast, skin, bladder, lung, and esophageal cancers. Choose strawberries with a robust color and a green crown.
Tomatoes. Although their peak season (June to August) is here, tomatoes should be eaten year-round. "They don't need to be fresh," Willett says. "That's important because they are very expensive in winter. Having a little bit of pasta sauce will actually be better for you." That's because there is a higher concentration of the antioxidant lycopene—protective against prostate and colorectal cancers—in a cooked tomato than in a raw one because the heat breaks down more cell walls of the tomato than our teeth can. But that doesn't mean you should shy away from fresh tomatoes, McKindley says. "We need to have a blend of raw and cooked because the cooking process will degrade other nutrients that are heat-sensitive like vitamin C and the B vitamins."
The American Institute for Cancer Research regularly updates its list of antioxidant foods and the research behind them.