Intake of dietary iron is low in patients with Crohn's disease: a case-control study

Patients with Crohn's disease (CD) often experience Fe deficiency (ID) and frequently alter their diet to relieve abdominal symptoms. The present study set out to assess whether patients with CD have dietary habits that lead to low Fe intakes and/or reduced bioavailable Fe compared with control subjects. Patients with asymptomatic CD were matched to controls (n 91/group). Dietary intakes of Fe and contributions from different food groups were compared using a 7 d food diary. Promoters and inhibitors of non-haem Fe absorption were investigated and a recently published algorithm was applied to assess bioavailable Fe. Fewer patients than controls met the reference nutrient intake for Fe (32% CD patients v. 42% controls). Overall, patients had significantly lower mean Fe intakes (by 2.3 mg/d) and Fe density (by 0.26 mg/MJ (1.1 mg/1000 kcal)) compared with controls (both P<0.001). Differences were mainly due to a preference among CD patients for low-fibre non-Fe fortified cereals, particularly breakfast cereals. In particular, control subjects had higher Fe intakes than matched CD subjects for men (P<0.001) and women less than 50 years (P=0.03). Intakes of both ascorbic acid (P<0.001) and phytic acid (P<0.01), but not animal tissue (P=1.0), were lower in patients with CD, but these had no overall effect on the predicted percentage of bioavailable Fe. Thus total bioavailable Fe was reduced in patients with CD due to lower intakes (P<0.01). Dietary Fe intakes are low in CD patients, which may contribute to an increased risk of ID and anaemia. Changing dietary advice may compromise perceived symptoms of the disease so the need for Fe supplementation should be carefully considered.