Role of naturally occurring dietary salicylates in Irritable Bowel Syndrome
Overall design: This was a pilot, double-blind, randomised, cross-over trial of low versus high-salicylate diets in IBS patients who had no previous exposure to a low chemical diet.
Materials: Participants were randomized by a computer-generated order to receive a diet either low or high in salicylate content for 14-days (6.6 and 27.9 g/day salicylate respectively). All food was provided. Participants and investigators were blinded to the diet. After the initial 14-days, the participants undertook a washout period of 7 days, where they resumed their habitual diet. No food was provided during this phase. During the washout phase, they completed a diary recording their symptoms and the amount and type of food they ate. This was followed by a cross-over to the alternate diet for further 14 days.
During the interventional dietary phases, all participants were provided with food and they completed information on the quantity of the provided foods consumed.
Interventional diets:
All foods including three main meals, morning and afternoon snacks, and drinks were provided. Detailed meal plans for high- and low-salicylate diets were provided to the participants. For some meals that included fresh salads, detailed recipes were provided for participants to prepare before consumption. They were strictly instructed to avoid eating out during the course of the study. If participants wanted to eat foods that were not specified on the supplied list, they contacted the study investigator for guidance on food choices.
Who provided intervention delivery & mode of delivery: The study investigator and two professional chefs prepared all foods in the commercial kitchen of Department of Dietetics, Monash University. Frozen complete meals were provided to the participants with instructions to thaw and heat before consumption. The foods were delivered bi-weekly free of charge to the participant homes.
The diets were designed based upon the salicylate content of foods. Both diets were free of gluten, preservatives, additives and lactose, were consistent in their levels of minimal FODMAPs (fermentable oligo- di- mono-saccharides and polyols), and contained moderate levels of amines and glutamates as per published food content to avoid any confounding factors that might affect the symptoms.
The average daily intake of salicylates in the low-salicylate diet was approximately 6 mg. The meal plans had an average energy value of 8 MJ daily and met the recommended serves of all food groups according to the Australian dietary guidelines.
Location: The intervention occurred within the participants home.
Personalisation: The intervention was not personalised to each patient.
Adherence: Compliance was monitored via the daily food diaries.
