Abstract
OBJECTIVES: The aim of this study was to evaluate the preventive effects of extra virgin olive oil (EVOO) or flaxseed oil (FO) on dextran sodium sulfate (DSS)-induced acute ulcerative colitis in female mice. METHODS: Eighty C57BL/6J mice of 8-weeks-old were divided in four groups: Control (SO), 10%EVOO, 10%FO and 5%EVOO+5%FO. The oils were given through the AIN-93M diet. After 30 days, animals were divided in four more groups, in which half received 3%DSS in water for 5 days. Body weight loss, bleeding and stool consistency were verified for the Disease Activity Index (DAI). Animals were euthanized and their colon and spleen weighted and measured. Histopathological analysis, the concentrations of TNF-α, IL-1β, and IL-10 and the iNOS expression were evaluated in the colon samples. RESULTS: Animals that received DSS presented with elevated disease activity index values; increased colon weight-to-length ratio; augmented leukocyte infiltration into the lamina propria and submucosa; and increased production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6, and greater inducible nitric oxide synthase expression in the distal colon. Individually or in combination, the oils were not able to reverse or mitigate any of the DSS-induced symptoms or damage. Additionally, the group of animals treated with DSS and supplemented with FO displayed increased spleen weight-to-body weight ratio, and the group that received a combination of EVOO and FO presented increased TNF-α levels compared with the respective control group. CONCLUSION: Consumption of large amounts of EVOO and FO as a treatment for or prevention against ulcerative colitis could potentially elicit unwanted adverse effects.
Link to Full Text
Key Points
Ulcerative colitis (UC) is an inflammatory bowel disease characterized by an immune system mediated response, resulting in deformation of the intestinal mucosa, leukocyte infiltration, increased proinflammatory cytokine production (tumor necrosis factor [TNF]-a, interleukin [IL]-1b, and IL-6), and upregulated expression of genes and proteins, like inducible nitric oxide synthase (iNOS), which releases abundant amounts of nitric oxide (NO). The present study was designed to investigate the protective effects extra virgin olive oil (EVOO) or flaxseed oil (FO) on dextran sodium sulfate (DSS)-induced acute ulcerative colitis in female mice. Previous studies investigating the chemical composition of EVOO and FO revealed that these oils are rich in MUFA and OA, and omega-3 ALA, respectively, and that each contains up to 800 mg/kg of phenolic compounds. The results of the present study failed to detect any potentially beneficial
effects associated with EVOO or FO, individually or in combination, when evaluating the inflammatory response of female mice with DSS-induced acute UC. Neither of the oils, individually or in combination, were able to prevent body weight loss or the UC-associated increased DAI. Low omega-6 PUFA content in the diet or insufficient proportions of fatty acids may be a reason why the diet failed to treat or prevent DSS-induced acute UC. Diets with a 2:1 ratio of omega-6 to omega-3 may present a more promising result than diets only rich in omega-3 PUFA. The oils were not able to decrease or reverse some of the classical signs of inflammation, including clinical and histologic impairment, increased concentrations of proinflammatory cytokines, or marked iNOS expression. In combination, the two oils evoked an increased histologic score for leukocyte infiltration and the concentration of TNF-a in the colon was significantly elevated, which could lead to more severe problems if left untreated. Therefore, physicians and nutritionists should be cautious when recommending the consumption of large daily doses of EVOO and FO for the prevention or treatment of UC.