We've all heard it since childhood: eat your vegetables.
But for adults that need more convincing, new research is compelling. By eating a plant-based diet that includes vegetables, fruits, whole grains and beans adults may reduce the risk of certain cancers.
The numbers add up: the more vegetables a person eats, the more she may benefit.
"More really does matter," says Elizabeth Pivonka, PhD, registered dietitian, president and CEO of the Produce for Better Health Foundation, Wilmington, Del.
Produce is rich in vitamin C, beta-carotene and folate, which may help prevent certain cancers, according to Pivonka.
Dietary fiber, only found in plant foods, is also key to protecting against colorectal cancer, according to a recent report from the World Cancer Research Fund/American Institute for Cancer Research's Continuous Update Project (CUP).
Evidence is convincing that a high-fiber diet may reduce colorectal cancer risk, according to the CUP report.
For every 10 grams of fiber that men eat, there's a 12-percent reduction in colorectal cancer risk; for women it's an 8-percent reduction (compared with no fiber; research ended at 35 to 40 grams of fiber a day), says Alice Bender, registered dietitian, American Institute for Cancer Research, Washington, D.C.
Fiber-rich whole grains rate their own medal in the battle against colorectal cancer.
"Three servings of whole grains a day is linked to a 21 percent decreased risk [compared with eating no whole grains]," Bender says.
Some health experts downplay the cancer-fighting role of produce.
The relationship between high produce consumption and overall reduced cancer risk isn't as strong as commonly thought, according to researchers at the Mount Sinai School of Medicine (New York City), who published their findings a year ago online in the Journal of the National Cancer Institute.
The differences, however, may be based on what scientists are looking at.
"Some studies look at all cancers as a class. AICR drills down to specific cancers [such as colorectal cancers], "Bender says.
Along with eating more fiber, adults can better protect themselves against colorectal cancer by reducing alcohol intake and red meat consumption, and find alternatives to processed meat, according to new recommendations from the American Institute for Cancer Research.
Aim for no more than 18 ounces of cooked red meat a week. Processed meat increases cancer risk twice as much as red meat. Being overweight and/or inactive also contributes to colorectal cancer, according to AICR research.
For those in the habit of pushing vegetables and whole grains to the side, it's time to rearrange the dinner plate.
Fruits and vegetables should take up half the real estate; grains, with an emphasis on whole, one quarter and protein one quarter, to follow the new MyPlate recommendations from the government (www.choosemyplate.gov).
When choosing produce, variety is important.
"Each has its own thumbprint for phytochemicals [beneficial plant substances]," Pivonka says.
Opt for a wide range of colors, not just the deep hues. White onions and pale green celery have phytochemicals not found in other vegetables, according to Pivonka.
Whole grains needn't be a challenge.
If you choose a whole-grain breakfast cereal and whole-wheat bread for a lunch sandwich you'll meet the recommendation to have three daily servings of whole-grain foods, Bender says.