Diets with high levels of fatty acids such as myristic acid (found in palm oil, coconut oil, and dairy fats) increased risk of flare in patients with ulcerative colitis (UC), researchers report in the September issue of Clinical Gastroenterology and Hepatology. Their findings, from a prospective study of more than 400 patients in remission during treatment with aminosalicylates, could guide future studies of supplements or compounds that reduce risk of flares in patients with UC in remission.
There is much interest in the relationship between diet and inflammatory bowel disease activity, but few consistent data support practical recommendations. Patients make intuitive associations between diet and IBD symptoms and disease activity, which can result in unnecessarily restrictive eating patterns and micronutrient deficiencies. As the incidence of UC and Crohn’s disease has increased in regions such as Asia, where IBD was previously uncommon, researchers have begun to investigate the roles of environmental factors such as the Western diet. Although associations between dietary factors such as fiber and IBD have been studied, many of these studies have used a retrospective design
Edward L. Barnes et al performed a prospective study of dietary patterns among 412 patients, from 25 sites, with UC in remission during monotherapy with an aminosalicylate (mesalamine, sulfasalazine, or balsalazide for at least 3 months before enrollment). Patients completed a validated food frequency questionnaire (on consumption of dairy, fruits, vegetables, eggs, meat, fish, cereals, breads, and starches, beverages, sweets, and baked goods) at enrollment and were followed for 12 months.
The authors hoped to compare patterns of macronutrient and micronutrient intake among patients who experienced a flare of UC with the dietary patterns of those patients who remained in clinical remission throughout the study period.
Forty-five patients (11%) had a relapse of UC within 1 year of study enrollment. The authors analyzed mean intake of specific nutrients and food groups. When analyzed in tertiles, increasing intake of multiple fatty acids was associated with increasing odds of relapse. In multivariable analysis, higher intake of myristic acid (odds ratio, 3.01) and alpha linolenic acid (odds ratio, 5.50) were associated with increased risk of relapse, although a dose–response relationship was retained only for myristic acid intake.
Other foods previously implicated in flares of UC, such as processed meat, alcohol, and foods high in sulfur, were not associated with an increased risk of flare.
Barnes et al say that because alpha linolenic acid is an n-3 polyunsaturated fatty acids (PUFA), they expected it to reduce odds of flare. However there was a significant risk of flare among patients in the medium intake tertile.
In an editorial that accompanies the article, Jason K Hou and James D Lewis explain that myristic acid has not been identified in prior studies to be associated with risk of IBD flares or development of IBD, but it has been implicated in increasing inflammation, increasing expression of interleukin 6 by macrophages.
Myristic acid is commonly found in coconut oil, palm oil, and dairy products.
Hou and Lewis say that prospective studies of the association of diet and the course of IBD are not easy to implement and can be expensive. The study by Barnes et al included participants in a clinical trial of mesalamine—a clever model that could be applied to other clinical trials to study the role of diet in IBD at relatively low cost.