Relationship between nickel allergic contact mucositis and nickel-rich diet in symptomatic women suffering from endometriosis

BACKGROUND: Nickel (Ni) is a ubiquitous element in nature and the gastrointestinal tract is an important route of exposure for humans. Once ingested, alimentary Ni often results in the allergic contact mucositis (ACM). Ni ACM is an emerging gastrointestinal disorder involving a type IV delayed hypersensitivity reaction and has an estimated prevalence that exceeds 30% of the general population. The resulting Ni-induced low-grade inflammation may present with both IBS-like symptoms and extra-intestinal manifestations. Gastrointestinal symptoms are also present in many women with endometriosis and Ni allergic contact dermatitis has already been observed in these women. Therefore, intestinal and extra-intestinal symptoms complained in endometriosis may depend on a Ni ACM. What is more, a low-Ni diet could suggestively improve symptoms. AIM: We wanted to study the prevalence of Ni ACM in women with symptomatic endometriosis and focus on the effects of a low-Ni diet on gastrointestinal, extra-intestinal and gynecological symptoms in these patients. MATERIALS AND METHODS: We consecutively recruited 34 women of fertile age (range 23-47 years, mean age 35 years) with endometriosis, symptomatic for gastrointestinal disorders. Sixteen out of 34 patients completed the study. They underwent Ni oral mucosa patch test (omPT), low-Ni diet and questionnaire for intestinal, extra-intestinal and gynecological symptoms. Clinical evaluation was performed at baseline (T0) and after 3 months (T1). RESULTS: Fourteen out 16 (87.5%) patients showed Ni omPT positive results, with Ni ACM diagnosis, whereas 2 out of 16 (12.5%) patients showed negative Ni omPT. After 3 months of low-Ni diet, all gastrointestinal, extra-intestinal and gynecological symptoms showed a statistically significant reduction (p <0.05) or a downward trend. CONCLUSIONS: Given the resulting high prevalence of Ni sensitivity and the significant clinical benefit obtained from a low-Ni diet, Ni-rich foods may be triggers of gastrointestinal, extra-intestinal and gynecological symptoms complained by women with endometriosis.