Researcher Susanna Larsson sums up the study's findings in an email to WebMD.
"Consumption of folate-rich foods (green leafy vegetables, cruciferous vegetables, oranges, legumes, whole grains) might lower the risk of pancreatic cancer. However, supplementation with folate (multivitamins) does not reduce the risk," Larsson tells WebMD.
Larsson works at the Karolinska Institute in Stockholm, Sweden.
Studying Pancreatic Cancer
The ACS predicts 33,730 new diagnoses of pancreatic cancer in the U.S. in 2006.
Larsson and colleagues studied nearly 82,000 men and women in Sweden for more than six years. When the study started, participants were in their early 60s, on average, and weren't known to have cancer.
Foods, Supplements Noted
Participants completed surveys about the foods they ate, serving sizes of those foods, and use of multivitamins or other supplements containing folate. The researchers then calculated folate intake.
The researchers didn't ask anyone to change their diets or start taking supplements. The study was purely observational; it didn't directly test folate for pancreatic cancer prevention.
During the study, the group had 135 diagnoses of pancreatic cancer. People with high folate intake from foods -- but not supplements -- were less likely to be diagnosed with pancreatic cancer.
The researchers adjusted for participants' age, smoking, and consumption of fruits and vegetables, which contain fiber and other nutrients besides folate. The results held, but it's always possible that folic acid consumption mirrored some other influence on pancreatic cancer risk.
The different results for food sources of folic acid and folic acid supplements were unexpected.
"Those findings were a surprise," Larsson tells WebMD. "However, two other studies found the same results."
The body absorbs more folic acid from supplements. The natural folic acid content in foods may drop as a result of food preparation.
The study doesn't pinpoint which foods participants ate. Good sources of folic acid include "green leafy vegetables, cruciferous vegetables, oranges, legumes, and whole grains," Larsson says.
Cruciferous vegetables include broccoli, cauliflower, brussels sprouts, cabbage, turnip greens, and kale. Legumes include lentils, fava beans, and peas.
In the U.S., enriched-grain products are fortified with folic acid. Such fortification isn't done in Sweden, Larsson says. Some U.S. breakfast cereals are fortified with the recommended daily intake of folic acid, which is 400 micrograms.