PHILADELPHIA (AP) — Women can reduce their risk of colon cancer by eating lots of fruits and vegetables rich in the B-vitamin folate, a study found.
The study, in Thursday’s issue of the Annals of Internal Medicine, tracked 121,700 U.S. nurses from 1976 to 1994. It found that women who had a high intake of folate from food or from multivitamins for at least 15 years were 75 percent less likely to get colon cancer.
A high-folate diet was defined as one consisting of at least four to five servings a day of leafy, green vegetables and fruits.
Foods rich in folate include spinach, romaine lettuce and broccoli. Orange juice is another good source, as are fortified breakfast cereals.
“We don’t want people to think that their diet doesn’t matter, that they don’t need to exercise, that they can just take a pill and prevent cancer,” said Dr. Edward Giovannucci of Harvard Medical School. “But someone taking folate in the long term will have a 75 percent reduced risk.”
While the study focused on women, increased levels of folic acid could help men too, researchers said.
Researchers believe folate, or folic acid, the form present in multivitamin supplements, is the key because the study found the same results in women who ate fruits and vegetables and those who took multivitamins.
Most multivitamins contain 400 micrograms of the vitamin, the recommended daily allowance. In contrast, a 6-ounce serving of orange juice or a cup of romaine lettuce contains 80 micrograms.
Dr. Kim Jessup, director of gastrointestinal oncology at the University of Pittsburgh Cancer Institute, questioned why it takes 15 years of eating folate for women to reduce their risk for cancer.
“This makes you think it might be a relatively weak effect,” said Jessup, noting studies that have shown aspirin can prevent 50 percent of colon cancers when used for more than one year.
Researchers aren’t sure exactly why folate seems to shield against cancer, but they suspect a folate deficiency can cause an increase in genetic mutations that raise the risk of the disease.
The American Cancer Society estimates that 95,600 people will be diagnosed with colon cancer this year, and 47,700 will die of the disease.