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Background:  Irritable bowel syndrome (IBS) is a chronic and relapsing bowel disorder that affects 12% of the UK population. Two-thirds of patients perceive their symptoms to be diet related (Simren, 2001) and restrict their food intake hoping to improve symptoms. This may put them at risk of low nutrient intakes. This study aimed to assess the dietary intake of IBS patients and compare nutrient intake to control subjects.

Methods:  Patients with IBS and controls were recruited from gastroenterology clinics from local hospitals. Controls were patients who were attending for colonoscopy surveillance for colon cancer or polyps and had a normal bowel habit with no history of IBS symptoms. Each consenting subject completed a validated food frequency questionnaire (FFQ; Bingham, 1997). Energy and nutrient intakes (excluding supplements) were calculated and comparisons were made between groups and with the UK DRVs. Data were compared between the IBS and control groups using unpaired t-tests or Mann–Whitney U-tests and a P < 0.05 was considered statistically significant. For nutrients with a significant difference, one-sample t-tests were used to determine the significance of any differences between the IBS group and DRVs.

Results:  Food frequency questionnaires were completed on 34 patients with IBS (35.3 ± 10.3 years; six male) and 17 controls (46.5 ± 9.8 years; 12 male). Energy and macronutrient intakes were similar between groups (Table 1). Intakes of calcium and iron were significantly lower in the IBS group than in controls. Nine women had a calcium intake and nine women had an iron intake below the reference nutrient intake. Twenty-five (74%) patients with IBS and eight (47%) controls (chi-squared test, P = 0.1) were taking supplements compared with 35% of respondents in the 2003 National Diet & Nutrition Survey. Nine (26%) patients with IBS and six (35%) controls (chi-squared test, P = 0.7) were taking either multivitamins or multivitamins & minerals.

Table 1.   Energy and nutrient intakes of controls and IBS patients
Energy and nutrient intakesIBSControlP-value
Mean (SD)
Energy (kcal) day−12000 (753)2258 (621)0.2
Protein (g) day−171.0 (24.8)71.3 (19.1)0.9
Fat (g day−1)83.4 (42.2)89.7 (35.9)0.6
Carbohydrate (g day−1)243.4 (103.5)270.0 (103.5)0.3
Fibre (NSP) (g day−1)20.6 (10.9)20.4 (7.8)0.9
Lactose (mg day−1)3.4 (3.7)2.3 (2.1)0.5
Calcium (mg day−1)580 (303)673 (192)0.03
Iron (mg day−1)9.6 (2.9)13.2 (4.1)0.001

Discussion:  Patients with IBS may be at risk of low micronutrient intakes. Consideration of calcium and iron intakes and multivitamin and mineral supplementation is important when giving dietary advice for the management of IBS.

Conclusions:  Patients with IBS should be assessed for inadequate intakes of key nutrients and supplements recommended where appropriate.

References  Bingham, S.A., Gill, C., Welch, A., Cassidy, A., Runswick, S.A., Oakes, S. et al. (1997) Validation of dietary assessment methods in the UK arm of EPIC using weighed records, and 24-hour urinary nitrogen and potassium and serum vitamin C and carotenoids as biomarkers. Int. J. Epidemiol. 26, S137–S151.

Simren, M., Mansson, A., Langkilde, A.M., Svedlund, J., Abrahamsson, H., Bengtsson, U. & Bjornsson, E.S. (2001) Food-related gastrointestinal symptoms in the irritable bowel syndrome. Digestion63, 108–115.