Researchers know that some foods can help prevent cancer. Now there is growing evidence that certain food combinations may offer more protection against cancer than any one specific food.
The following combinations of foods are especially beneficial. Eat them regularly—either at the same meal or separately throughout the week…
Results of an animal study presented at the American Institute for Cancer Research International Research Conference showed that rats with tumors that were given a diet of tomatoes and broccoli had significantly smaller tumors than animals fed one of these foods.
The lycopene in tomatoes is an antioxidant. Antioxidants are crucial for preventing cancer because they help prevent unstable molecules, called free radicals, from damaging cell structures and DNA. Broccoli contains chemical compounds known as glucosinolates, which may be effective in flushing carcinogens from the body.
Also helpful: Combine broccoli or other cruciferous vegetables, such as brussels sprouts and cabbage, with foods that are high in selenium, such as shellfish and Brazil nuts. A study published by the UK’s Institute of Food Research found that the combination of broccoli’s glucosinolates and selenium has more powerful anticancer effects than either food eaten alone.
These potent cancer-fighting vegetables also are rich in vitamin C and folate, as well as phytonutrients that deactivate carcinogens. When eaten in combination, brussels sprouts and broccoli may provide more protection than either one eaten alone.
Brussels sprouts have the phytonutrient crambene, which stimulates phase-2 enzymes, substances that help prevent carcinogens from damaging DNA. Broccoli is high in indole-3-carbinol, a phytonutrient that also stimulates phase-2 enzymes—but in a different way.
Each of these foods is very high in antioxidants. In a recent laboratory analysis, researchers measured the amount of antioxidants in each of these fruits individually. Then they combined them and took additional measurements. Result: The mixture of fruits was more powerful against free radicals than any one fruit alone.
Curcumin is a phytonutrient found in the spice turmeric. Quercetin is a phytonutrient that is abundant in yellow onions, especially in the outermost rings. According to a small study in Clinical Gastroenterology and Hepatology, people who consumed large amounts of these two phytonutrients had a reduction in the number of colon polyps, growths that may turn into cancer.
The study looked at a small number of people with familial adenomatous polyposis, a hereditary condition that increases the likelihood of developing polyps. The phytochemical combination reduced the number of polyps by 60%. It also caused some polyps to shrink.
The researchers used concentrated forms of curcumin and quercetin. You would have to eat two-and-a-half tablespoons of turmeric daily to get a comparable amount. To get the necessary amount of quercetin, you would need to have about two-thirds cup of chopped onions daily.
Recommended: Eat a variety of herbs and spices to get the most phytonutrient protection. Even small amounts used frequently will impact your health over time. Among herbs, rosemary and oregano rank among the best phytonutrient sources. Ginger is another powerful spice.
The lycopene in tomatoes is particularly effective against prostate cancer?but only when it’s consumed with a small amount of fat. Lycopene, like other members of the carotenoid chemical family, is a fat-soluble substance. The body can’t absorb it efficiently in the absence of fat.
It takes only three to five grams of fat (about one teaspoon of oil) to improve the absorption of lycopene from tomatoes. For example, you could have a salad with an oil-based dressing. The type of fat doesn’t matter for absorption of lycopene and other carotenoids, but you might as well choose a fat that promotes health. Olive oil and canola oil are good choices.
In a recent study published in The Journal of Nutrition, researchers divided 106 women into two groups. All of the women were asked to eat eight to 10 servings of fruits and vegetables daily for two weeks. However, one of the groups (the high-diversity group) was told to include foods from 18 different botanical groups, including onions and garlic from the allium family, legumes, cruciferous vegetables, etc. The other group (the low-diversity one) was asked to concentrate all its choices among only five major groups.
Results: Women in both groups showed a decrease in lipid peroxidation—important for reducing the risk of cancer and heart disease. However, only the women in the high-diversity group showed a decrease in DNA oxidation, one of the steps that initiates cancer development.
The ways that chemicals work in the body, known as metabolic pathways, have a rate-limiting effect. This means that beyond a certain point, eating more of a specific food won’t provide additional protection. Eating a wide variety of foods brings more metabolic pathways into play, thus bypassing this limiting effect.
Source: Karen Collins, RD, registered dietitian and nutrition adviser to the American Institute for Cancer Research (www.aicr.org). A syndicated newspaper columnist and public speaker, she maintains a private nutrition counseling practice in Washington, DC.