Study leader Dr. Andrew Hart of the University of East Anglia and colleagues compared the diets of those who developed ulcerative colitis -- an intestinal disease characterized by pain, diarrhea and weight loss -- with those who did not develop the disease and found those with the highest intake of a substance found in olive oil -- oleic acid -- had a 90 percent lower risk of developing the disease.
"Oleic acid seems to help prevent the development of ulcerative colitis by blocking chemicals in the bowel that aggravate the inflammation found in this illness," Hart says in a statement.
Oleic acid is a monounsaturated fatty acid also found in butter as well as some other oils -- including peanut and grape seed.
Hart and colleagues studied more than 25,000 people ages 40-65 living in Norfolk -- part of the European Prospective Investigation into Diet and Cancer recruited between 1993 and 1997 -- who had completed detailed food dairies. None had ulcerative colitis at the study's outset, but 22 participants had developed ulcerative colitis by 2004.
The findings were presented at the Digestive Disease Week conference in New Orleans.