Broccoli may not be America's best-loved vegetable, but it undoubtedly tops the list of health-promoting foods, especially when it comes to preventing certain types of cancer.

Scientists have isolated compounds from broccoli that appear to slow — or even stop — the progression of bladder cancer. In a study conducted at Harvard University and Ohio State University, researchers found that men who ate two or more half-cup servings of broccoli per week had a 44 percent lower incidence of bladder cancer than men who ate less than one weekly serving of broccoli.

The compounds responsible for broccoli's cancer-fighting effect are isothiocyanates (ITCs) and sulforaphanes. Also found in other cruciferous vegetables, including cabbage, kale and collard greens, sulforaphanes appear to boost the body's defenses against cancer, while ITCs have been shown to trigger cancer cell death.

If you haven't acquired a taste for broccoli spears, you might enjoy broccoli sprouts. Sprouts are not only tender and tasty, they offer approximately 30 times more cancer-fighting ITCs and 50 times more sulforaphanes than mature broccoli.

Earlier this year, researchers at Roswell Park Cancer Institute in Buffalo, N.Y., reported that concentrated extracts of freeze-dried broccoli sprouts reduced the development of bladder tumors in rats by more than half.

Whether you prefer your broccoli in the form of spears or sprouts, the best way to eat it is raw. Because heat can destroy cancer-fighting ITCs, cooked broccoli may provide 60 percent to 90 percent fewer ITCs than the raw form of the vegetable.

The benefits of broccoli go well beyond offering protection against bladder cancer. The results of a study published in The Journal of Nutrition suggest that regular consumption of broccoli and other cruciferous vegetables may play an important role in reducing the risk of breast cancer in pre-menopausal women.

At the University of California, Los Angeles, researchers discovered that eating broccoli can boost the protective powers of the body's immune system and may even prevent some of the expected age-related decline in immunity. The UCLA scientists found that older mice treated with sulforaphanes from broccoli exhibited significantly improved immune responses, similar to those typically observed only in young mice.

Scientists have known for years that eating broccoli and other vegetables is good for the heart. Most veggies are rich sources of heart-healthy compounds, including vitamins, minerals, fiber and antioxidants.

In a recent article published in the Journal of Agriculture and Food Chemistry, researchers reported that broccoli-fed animals had improved heart function and less heart muscle damage after bouts of oxygen deprivation. The researchers noted that broccoli benefits the cardiovascular system by boosting levels of a protective protein called thioredoxin.

In a study funded by the National Cancer Institute, researchers at the University of Pittsburgh Cancer Institute showed that the ITCs in broccoli appear to be highly effective in suppressing the growth of human prostate cancer cells.

At Cancer Care Ontario in Toronto, a team of scientists collected and analyzed data from more than 1,300 men diagnosed with prostate cancer. The team found that although eating fruits and vegetables wasn't associated with a decreased prostate cancer risk in general, greater consumption of dark green and cruciferous vegetables was linked to a marked reduction in the risk of developing aggressive prostate cancer.

Regular consumption of broccoli offers excellent cancer protection, but the protection provided by the combination of broccoli and tomatoes may be even better. At the University of Illinois, researchers found that prostate tumors shrank more in rats fed extracts of broccoli and tomatoes together than the tumors in rats fed either substance alone.

The scientists concluded that different bioactive compounds in each of the plant foods work on different anti-cancer pathways, producing a powerful additive effect. Tomatoes are rich in the phytonutrient lycopene, a red pigment with proven cancer-fighting properties.

While raw broccoli appears to offer greater cancer protection than cooked broccoli, processed and heated tomato products may be more beneficial in fighting prostate cancer than raw tomatoes. Slicing, dicing and heating tomatoes make their cancer-fighting compounds easier for the body to absorb and use.

At a time when only about 23 percent of American adults eat the recommended five to nine servings of fruits and vegetables a day, most of us could stand to boost our intake. The best way to get all the health-promoting benefits of broccoli, tomatoes and other plant foods is simply to eat them.

Rallie McAllister is a board-certified family physician, speaker and the author of several books, including "Healthy Lunchbox: The Working Mom's Guide to Keeping You and Your Kids Trim." Her website is www.rallieonhealth.com. To find out more about Rallie McAllister, M.D., and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com.

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