ORIGINAL ARTICLEDietary beliefs of people with ulcerative colitis and their effect on relapse and nutrient intake
Introduction
Ulcerative colitis (UC) is chronic inflammatory disorder of the colon of unknown cause. The clinical syndrome is characterised by a relapsing and remitting course associated with bouts of diarrhoea, often bloody, with urgency of defaecation. The aetiology of UC has not been clearly defined, but as UC is an enteric condition there are logical reasons to consider dietary factors in the aetiopathogenesis of UC.
Studies that have examined the role of dietary factors in UC have primarily investigated the influence of food on the development of the disease. Epidemiological studies, albeit with controversial methodology and inconsistent results, have examined the relationship between dietary intake and the onset of UC.1., 2., 3., 4., 5. The impact of food on the course of disease has been examined only for a small number of specific dietary factors, for instance milk and dietary fibre. The relationship between the disease and plasma folate levels has also been studied. Some workers have recorded patients’ beliefs but not examined them with respect to the characteristics of their disease or dietary advice. Nor has the influence of patients’ food beliefs on nutrient intake or the risk of relapse been examined.
The role milk and dairy products play as causative factors for relapses of UC has been debated since Truelove described a marked symptomatic and histological improvement for a small group of UC patients on a milk-free diet.6 In the controlled trial that followed, patients on a milk-free diet were found to be less likely to relapse than controls.7 However, this study can be criticised for non-randomisation, non-blinding and failure to monitor the dietary intervention. Despite these criticisms the belief that milk is problematic in UC is widespread.8 The data for dietary fibre are similarly contradictory. Dietary fibre in addition to standard treatment significantly improved symptoms in a group of patients with UC,9 but in a non-randomised study comparing sulfasalazine with bran fibre there were more relapses for the patients taking bran.10 A more recent multi-centre randomised controlled trial compared the maintenance of remission with mesalazine, dietary fibre alone and mesalazine plus dietary fibre11 and demonstrated that dietary fibre alone was as efficacious as standard treatment. However, this study was potentially biased by not being blinded for treatment or assessment of outcome.
Many UC patients have a low concentration of serum or red cell folate due to a combination of factors including competitive inhibition of folate absorption by sulfasalazine,12., 13., 14. haemolysis,13., 14. increased intestinal cell turnover15 and dietary deficiency.14 The role of folate deficiency in the development of colon cancer in patients with UC is suspected but unproven from cohort and case control studies.16., 17. Folate supplementation may reduce the risk of colon cancer.18
It is perhaps not surprising, given the disparate results from studies examining the role of diet on disease course, that patients with UC are confused about the role dietary factors play in their disease and a wide range of beliefs are expressed. Patients with UC consider dietary factors to be relevant to their disease and often claim to modify their intake because of those beliefs. For instance, 64% of patients with UC reported intolerance to one or more foods compared with 14% of controls.19 A wide range of foods were cited as causing symptoms, although most commonly these were vegetables, fruit or milk products. Another study found that patients restricted their diet because certain foods made them feel unwell.20 In this study certain foods, most commonly milk and dairy products, but also liver, diet drinks and artificial sweeteners, were never eaten by 40% of the group. Similarly, 71% of paediatric UC patients altered their diets to avoid foods that they felt worsened their condition, usually milk, and symptoms were reported to improve subjectively as a result in 73%.21
Firmly held nutritional beliefs may be associated with an adverse clinical outcome such as a greater risk of relapse, osteoporosis secondary to calcium deficiency or potentially colon cancer due to folate deficiency. Identifying pre-existing beliefs is the first step in attempting to modify behaviour. Therefore, this study is important for not only identifying the nutritional beliefs held by patients but also to explore why patients hold those beliefs and for determining the extent to which those beliefs influence the clinical course of the disease.
Section snippets
Aims
The aims of this study were threefold:
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to determine the proportion of patients with UC who believed that foods modified disease activity and the nature of those beliefs, specifically which foods were believed to be helpful, harmful or to have triggered a relapse in the past. We wished to determine if any patient or disease characteristic was associated with holding food beliefs;
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to examine the relationship between reported behaviour and the risk of relapse;
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to determine the influence that food
Methods
The study design was a prospective cohort study in which a group of patients with UC in clinical remission was followed for 1 year. A qualitative assessment of nutritional beliefs and a quantitative assessment of nutritional intake were made at recruitment. Habitual diet was measured using a validated food frequency questionnaire and the outcome, clinical relapse or remission, was determined with a disease activity index.
The study had ethical approval from Newcastle and North Tyneside Joint
Patient recruitment and demographics
Replies were received from 355 of the 463 patients who were invited to participate in the study, a 77% response rate. Of those who responded, 83 actively declined participation in the study, and a further 81 were found to have exclusion criteria. Therefore, 191 participants were recruited to the study. There was no significant difference between participants and non-participants for age (P=0.07) or gender (P=0.76). Follow-up was complete in 183 patients (representing a drop-out rate of 4%) and
Discussion
This study has shown that the majority of patients with UC believe that food is relevant to their colitis and have tried to modify their diet accordingly. Common food beliefs have been determined and differences between patients who do and do not hold food beliefs explored. We have shown that those beliefs do not influence disease outcome but can reduce the intake of important nutrients.
Potentially there was a recruitment bias in this study that may have falsely elevated the proportion of
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