Urinary nitric oxide metabolites in children with celiac disease after long-term consumption of oats-containing gluten-free diet

Abstract

Objective. Oats are accepted in the gluten-free diet (GFD) for children with celiac disease (CD). Some reports have indicated, however, that not all celiac patients tolerate oats. We have previously shown that some children still have high levels of urinary nitric oxide (NO) metabolites as markers of intestinal inflammation after 1 year on GFD with oats. In this study, we measured urinary NO metabolites in CD children who had been consuming oats-containing GFD for an extended, 2–6-year period, also taking into consideration ordinary consumption of nitrite/nitrate-rich foods close to the urine sampling. Materials and Methods. Morning urinary nitrite/nitrate concentrations were measured in 188 pediatric CD patients. A questionnaire was used to elucidate factors possibly affecting the urinary levels, for example, dietary factors, asthma, or urinary tract infection. Results. Oats were consumed by 89.4% of the patients for a median time of 3 years. The median nitrite/nitrate level was 980 μM. The majority (70.2%) who consumed oats had low levels of urinary nitrite/nitrate, that is, <1400 μM, while 29.8% demonstrated high levels, that is, >1400 μM. Nitrite/nitrate-rich foods did not significantly influence the urinary concentrations. Conclusion. The urinary levels of NO metabolites revealed two subpopulations, one with high and one with low levels. The high levels could be possibly due to poor adherence to the GFD, sensitivity to oats, or some unknown factor(s). Nitrate-rich foods, asthma, or urinary tract infection did not affect the result. The elevated levels of NO metabolites could indicate mucosal inflammation and pinpoint the need of careful follow-up of children on oats-containing GFD.

Key Words::

• celiac disease
• gluten-free diet
• oats
• urinary nitrite/nitrate.

Acknowledgments

We would like to thank Dr. Jan-Åke Hammersjö, Västervik, and our patients and their parents for taking part in this study. We are particularly grateful for the assistance given by nurses and dieticians, especially Katarina Larsson, at the pediatric clinics in Linköping, Norrköping, Motala, and Västervik for collecting patients’ data and urine samples. The study was financially supported by the Medical Research Council of Southeast Sweden, the County Council of Östergötland, and The Swedish Research Council.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.