Dietary fortificant iron intake is negatively associated with quality of life in patients with mildly active inflammatory bowel disease

Abstract

Background: Iron deficiency anaemia and oral iron supplementation have been associated negatively with quality of life, and with adverse effects, respectively, in subjects with inflammatory bowel disease (IBD). Hence, the risk-benefit ratio of oral iron is not understood in this patient group. The present case-control study investigated whether dietary iron intake impacts on quality of life in IBD patients.

Methods: Quality of life, habitual dietary iron intakes and iron requirements were assessed in 29 patients with inactive or mildly active IBD as well as in 28 healthy control subjects.

Results: As expected, quality of life was worse in IBD patients as a whole in comparison to healthy controls according to EuroQol score and EuroQol VAS percentage (6.9 ± 1.6 vs 5.3 ± 0.6; p< 0.0001 and 77 ± 14% vs 88 ± 12%; p=0.004 respectively). For IBD subjects, 21/29 were iron deplete based upon serum iron responses to oral iron but, overall, were non-anaemic with mean haemoglobin of 13.3 ± 1.5 g/dL, and there was no difference in their quality of life compared to 8/29 iron replete subjects (Hb 14.0 ± 0.8 g/dL). Interestingly, total dietary iron intake was significantly negatively associated with quality of life in IBD patients, specifically for non-haem iron and, more specifically, for fortificant iron. Moreover, for total non-haem iron the negative association disappeared when fortificant iron values were subtracted. Finally, further sub-analysis indicated that the negative association between (fortificant) dietary iron intake and quality of life in IBD patients is driven by findings in patients with mildly active disease rather than in patients with quiescent disease.

Conclusions: Iron deficiency per se (i.e. without concomitant anaemia) does not appear to further affect quality of life in IBD patients with inactive or mildly active disease. However, in this preliminary study, dietary iron intake, particularly fortificant iron, appears to be significantly negatively associated with quality of life in patients with mildly active disease.

Figure 1

Association between quality of life measured with McMaster IBDQ with A) total dietary iron, B) non-haem iron, C) haem iron, and D) fortificant iron in IBD patients: E) association between IBDQ score and dietary iron intake as per a) in relation to disease activity. r, Pearson correlation coefficient; p, p-value for the slope deviation from zero.

Figure 2

Association between quality of life measured with EuroQol VAS percentage with A) total dietary iron, B) non-haem iron, C) haem iron and D) fortificant iron in IBD patients: E) association between EuroQol VAS percentage and dietary iron intake as per a) in relation to disease activity. r, Pearson correlation coefficient; p, p-value for the slope deviation from zero.

Figure 3

Association between quality of life measured with A) McMaster IBDQ and B) EuroQol VAS percentage for ‘natural’ dietary non-haem iron in IBD patients. Natural non-haem iron represents not-added, dietary-derived iron, calculated by subtracting fortificant iron from total non-haem iron.