Recurrence of gastrointestinal and extra-intestinal symptoms in celiac patients affected by nickel allergic contact mucositis: when proper gluten-free diet is not enough

BACKGROUND AND AIM: Nickel (Ni) is a metal widely present in nature and the prevalence of Ni allergy is increasing. Allergic contact mucositis (MAC) induced by Ni-rich foods is often responsible for IBS-like disorders and it can be diagnosed by means of a Ni oral mucosa patch test (omPT). It has been observed that, after several months of correct gluten-free diet (GFD), many celiac disease (CD) patients show a recrudescence of gastrointestinal and extra-intestinal symptoms, although serological and histological remission has been achieved. This can be due to a Ni load induced by GFD: a greater consumption of Ni-rich foods (e.g. corn) would lead to a consequent intestinal sensitization to Ni in predisposed subjects. Our study aimed to assess the role played by Ni in the recurrence of symptoms in CD subjects after strict GFD. MATERIAL AND METHODS: Twenty celiac patients (all female, age 23-65 yrs) in serological and histological remission after at least 12 months of GFD have been consecutively included: they all were complaining recurrence gastrointestinal and extra-intestinal symptoms. Subjects with organic gastrointestinal pathologies were excluded. A symptom questionnaire (GSRS modified according to the Salerno Experts' Criteria) has been administered to all patients in 4 stages: T0 (during free diet - active CD); T1 (after 12 months of GFD - CD remission); T2 (during GFD - recurrence of symptoms); T3 (during GFD and after 3 months of low-Ni diet). Ni omPT was performed at T2. Statistical analysis was performed using Wilcoxon signed rank test. RESULTS: All 20 patients showed positive Ni omPT, with local and/or systemic alterations confirming Ni ACM diagnosis. The analysis obtained by comparing T2-T3 showed p-value <0.01 for: abdominal pain, bloating, swelling, increased number of evacuations, dermatitis, asthenia; p-value values <0.05 for: heartburn, acid regurgitation, borborygmus, flatulence, loose stools, urgent need for defecation, headache. The other variables were statistically not significant. CONCLUSIONS: Our data suggest that gastrointestinal and extra-intestinal symptoms observed in CD subjects after prolonged and correct GFD may be due to the necessary dietary change and an increased Ni intake. Specifically, these patients developed Ni MAC, diagnosed by specific Ni omPT. We also observed that regression of symptoms may occur after a proper low-Ni diet. We can conclude that GFD may lead to an increased consumption of Ni-rich foods and this could explain the recurrence of apparently gluten-dependent symptoms.