Olive, Peanut, and Grapeseed Oils May Protect Against the Development of Ulcerative Colitis

Oleic acid in one's diet may help reduce or prevent the development of ulcerative colitis (UC). Oleic acid, a monounsaturated fatty acid, is present in olive, peanut, and grapeseed oils and may prevent ulcerative colitis from developing by suppressing inflammation by blocking chemicals in the bowel that aggravate inflammation. UC affects men and women of all ages and is characterized by inflammation of the lining of the colon or large bowel, which can cause distressing symptoms such as abdominal pain, diarrhea and weight loss.

Researchers led by Andrew R. Hart, MD, senior lecturer in gastroenterology, University of East Anglia, Norwich, U.K., sought to determine whether people eating more oleic acid are protected against developing UC. They studied more than 25,000 men and women aged 40 to 65 years in Norfolk, England, who were recruited between 1993 and 1997 into a study called EPIC (European Prospective Investigation into Diet and Cancer). These participants, initially without UC, completed a diary of all the foods they ate for one week including foods eaten, the quantity and brands in detail.

The diaries were then coded by specially trained nutritionists using a specific computer program called DINER. The nutritionists, using DINER, calculated the dietary intake of different foods consumed by participants, including oleic acid. Patients were followed up to 2004 to identify those who were subsequently diagnosed with UC. Researchers compared any differences in diet, including oleic acid, between those who were diagnosed with UC and those who remained healthy.

The study found that individuals with the highest intake of oleic acid had a 90 percent lower risk of developing UC. Dr. Hart estimates that approximately half the cases of UC could be prevented if larger amounts of oleic acid were consumed — as much as two to three tablespoons of olive oil per day could have a protective effect.

Dr. Hart said similar work in other countries is now required to determine if the results are reproducible and consistent in other groups. These are required to confirm whether oleic acid is truly protective. If so, researchers believe that dietary modifications may prevent this distressing illness and that the use of oleic acid supplements should be clinically assessed as treatment for patients with UC. Additionally, while most conditions are treated with drugs rather than dietary treatments, Hart noted that a proven complementary approach using both may be a research topic for the future to benefit more patients.

"If we could show that dietary treatments complement drug treatments then that could have a better outcome than either approach by itself," he said. "This is critical since many patients with UC have to take medications life-long, may need surgery and have an increased risk of complications including cancer and perforation of the large bowel."