A bowl full of bright green steamed broccoli. You say either "Yum!" -- or "Where's the double cheeseburger?" But you know the broccoli is good for you, especially without melted cheese. The question is, how good? And more to the point, can it -- or any food -- help prevent disease, such as cancer?
The answer is yes -- some foods do show cancer-fighting properties, though no one is yet able to say one food or another can prevent or stop cancer in its tracks. Still, a body of research suggests an overall healthy diet filled with colorful fruits and vegetables is the key to skirting heart disease, diabetes, and possibly cancer too.
In fact, scientists know more about what not to eat -- processed meats, salty foods, sugary drinks, huge helpings of red meat -- than which fruits and vegetables to pile on your plate. But they do know those foods matter.
A comprehensive review of thousands of studies on diet, physical activity, and weight conducted for the World Cancer Research Fund and the American Institute for Cancer Research pointed to the benefits of eating mostly foods of plant origin. Foods such as broccoli, berries, and garlic showed some of the strongest links to cancer prevention.
They're low in calories and fat and power-packed with phytochemicals and antioxidants that may help reduce your cancer risk.
Antioxidants, Phytochemicals, and Cancer
You've heard of antioxidants, such as vitamin C, lycopene, and beta-carotene, which are in many fruits and vegetables. Studies suggest that people who eat meals that are rich in fruits and vegetables have a lower risk of cancer. A variety of chemicals from plants known as phytochemicals also seem to protect cells from harmful compounds in food and in the environment, as well as prevent cell damage and mutations, says Jed W. Fahey, ScD, MS, an assistant professor at Johns Hopkins Bloomberg School of Public Health and its School of Medicine who studies how cruciferous vegetables help protect against disease.
A diet that could ward off cancer really doesn't look that different from the healthy foods you should be eating anyway, says Wendy Demark-Wahnefried, PhD, RD,associate director for Cancer Prevention and Control at the University of Alabama’s Comprehensive Cancer Center. That means plenty of fruits and vegetables, as well as whole grains and lean meat or fish.
And weight matters too. Keep the scale at a healthy number and shed some pounds if needed. Being overweight or obese increases your risk of developing esophageal cancer, postmenopausal breast cancer, colorectal cancer, endometrial cancer, ovarian cancer, and others.
So what foods should you load up on to give your body the best chance of steering clear of cancer? WebMD scrutinized research, sometimes conflicting, to tease out some foods you'll want to eat plenty of, starting right now.
Garlic: Stinky Breath, but Super Healthy
Whoever thought garlic breath would be good for you? The same sulfur compounds causing that odor may also stop cancer-causing substances from forming in your body, speed DNA repair, and kill cancer cells.
Want more? Garlic battles bacteria, including H. pylori (the one connected to some ulcers and stomach cancer), and research suggests it reduces the risk of developing stomach, colon, esophageal, pancreatic and breast cancers. To get the most benefit, peel and chop the cloves and let them sit 15 to 20 minutes before cooking. That activates enzymes and releases the sulfur-containing compounds that have the most protective effect, says Colleen Doyle, MS, RD, managing director of nutrition and physical activity at the American Cancer Society.
The World Health Organization recommends that adults consume approximately one clove of garlic daily to promote good health.
Garlic is the powerhouse of the allium family, but onions, leeks, chives, and scallions might also protect against stomach cancer, some research suggests.
Broccoli: Phytochemical Powerhouse
Eat your broccoli, mom always said. She was right. Broccoli and other cruciferous vegetables such as cabbage, kale, and cauliflower contain phytochemicals called glucosinolates, which produce protective enzymes that are released when you chew the raw veggie, rupturing the cell walls.
Your body also produces those enzymes in the intestines, Fahey explains, and when raw or cooked broccoli passes through, the enzymes are activated.
One of the most protective of these enzymes is sulforaphane. "Broccoli is the best source of this particular compound," says Fahey, who studies sulforaphane in broccoli and broccoli sprouts. Scientists are researching how sulforaphane might reduce cancer risk, from detoxifying harmful substances (such as smoke and other environmental pollutants) in the body to operating as a kind of antimicrobial agent by attacking the bacterium H. pylori.
Broccoli and its cousins are most protective against cancers of the prostate, lung, colon, breast, bladder, liver, neck, head, mouth, esophagus, and stomach, according to a review of hundreds of clinical studies conducted for the World Cancer Research Fund and the American Institute for Cancer Research and other studies.
Tomatoes: Potential Weapon Against Prostate Cancer
The red coloring in tomatoes makes a juicy, ripe one hard to resist -- and makes them a potential weapon against prostate cancer and heart disease. That red hue comes from a phytochemical called lycopene, a powerful antioxidant, which is most concentrated in tomatoes. Several studies suggest that a lycopene-rich diet is connected to a reduced risk of prostate cancer.
However, researchers aren't yet sure if the sources and types of lycopene act differently on cells and whether other dietary and lifestyle factors play a role in reducing prostate cancer risk.
In laboratory tests, lycopene has stopped other types of cancer cells from growing, including breast, lung, and endometrial (in the lining of the uterus). Researchers speculate that lycopene protects cells from damage that could lead to cancer by boosting the immune system. And they suspect lycopene stops the growth of tumors by interfering with abnormal cell growth, according to the American Institute for Cancer Research.
To get the most benefit from lycopene, eat cooked or processed tomatoes, including tomato juice and pizza sauce. Processing makes the cancer-fighting compounds more available to your body because heat breaks down the plant's cell walls. And including processed tomatoes in dishes with oil such as pizza and pasta with sauce boosts the availability of lycopene. Want more of this compound? Munch on some watermelon, pink grapefruit, or red bell peppers.
Strawberries: Rich in Antioxidants
Berries scoop up disease-fighting honors like kids in sports collect trophies: They just keep multiplying. Research points to possible protection against heart disease and memory decline as well as cancer. In a recent study, berry extracts slowed the growth of cancer cells; specifically, strawberry and black raspberry extracts had the greatest impact on colon cancer cells.
Strawberries and raspberries are rich in antioxidants such as vitamin C and ellagic acid, a phytochemical. In laboratory tests, ellagic acid seems to have anticancer properties that rev up enzymes, which destroy cancer-causing substances and slows the growth of tumors. It seems to prevent cancers of the skin, bladder, lung, esophagus and breast. They also contain flavonoids, which suppress an enzyme that damages DNA and has been linked to lung cancer. Other types of berries, all rich in flavonoids, deserve a spot on your plate, too: blackberries, blueberries, and cranberries. Blueberries are packed with anthocyanins, which reduce inflammation and are one of the most powerful antioxidants, Fahey says. He considers berries and cruciferous vegetables the most powerful protective foods.
Eating fruits (including berries) and vegetables probably decreases the risk of lung cancer and could prevent cancers of the mouth, throat, larynx, esophagus, stomach, pancreas, and prostate, according to a review of hundreds of clinical studies conducted for the World Cancer Research Fund and the American Institute for Cancer Research.
Carrots: Best Eaten Cooked
One of the easiest vegetables to love, carrots are packed with disease-fighting nutrients. They contain beta-carotene, an antioxidant scientists believe may protect cell membranes from toxin damage and slow the growth of cancer cells. And carrots deliver other vitamins and phytochemicals that might guard against cancers of the breast, mouth, pharynx, larynx, esophagus, and stomach.
Some studies suggest carrots protect against cervical cancer, perhaps because they supply antioxidants that could battle HPV (human papilloma virus), the major cause of cervical cancer. Plus, carrots contain falcarinol, a natural pesticide that may have anti-inflammatory effects.
Scientists in England found that rats given falcarinol were less likely to develop cancerous tumors.
Cooked carrots supply more antioxidants than raw, according to a report in the Journal of Agriculture and Food Chemistry. If you're cooking carrots, leave them whole while steaming or boiling, and cut them after they're done. That reduces the loss of nutrients, including falcarinol, and gives them a sweeter taste as well.
Spinach: A Super Carotenoid Source
Spinach is rich in lutein and zeaxanthin, carotenoids that remove unstable molecules called free radicals from your body before they damage it. They're found in spinach and other dark green leafy vegetables, and some studies show they could protect against cancer of the mouth, esophagus, and stomach. An NIH/AARP study of more than 490,000 people found that those who ate more spinach were less likely to develop esophageal cancer. Some studies suggest the carotenoids in spinach and other foods reduce the risk of ovarian, endometrial, lung, and colorectal cancer, too.
Throw in folate and fiber, which researchers think might trim the risk of certain cancers, and you've got nutritional powerhouse in every dark green leaf. Folate helps your body produce new cells and repair DNA, and is especially important for women of childbearing age because it can prevent neural tube defects in a developing fetus. You'll get the most lutein from raw or lightly cooked spinach. Enjoy it in a salad, steamed, or sautéed with garlic and olive oil, or stirred into soups. For a change, substitute kale, collard greens, Swiss chard, or romaine lettuce. But spinach is the star. "Out of the leafy greens, spinach is one of the most nutrient-dense," Doyle says.
Whole Grains: Good for the Whole Body
The next time you step up to the deli counter, remember this: Bland white bread can't compete with hearty whole wheat in taste or nutrition. Maybe you've heard about revised federal nutrition guidelines that recommend half of all the grains you eat -- rice, cereal, and even chips -- should be whole. That's why even sugary kids' cereals and frozen pizzas are loading up on whole-grain ingredients.
Whole grains deliver plenty of fiber, but while diets high in vegetables and fruits have been linked with a decreased risk of colorectal cancer, it isn't yet clear how dietary components, such as fiber and certain types of fats, affect colorectal cancer risk. Still, whole grains contain other substances that might battle cancer, including lignans, which act as antioxidants, and saponins, which could keep cancer cells from multiplying. Look for bread labeled "100% whole wheat" rather than simply "wheat bread," which likely contains refined grains. For even more lignans, choose a whole wheat bread sprinkled with flax or sesame seeds.