Zinc deficiency may be a cause of burning mouth syndrome as zinc replacement therapy has therapeutic effects

Background: Zinc is known to play an important role for growth and development, the immune response, neurological function, and reproduction. Although the etiology of burning mouth syndrome (BMS) is unknown, zinc deficiency may be implicated in the pathogenesis of BMS. The aim of this study was to demonstrate a causal relationship between zinc deficiency and BMS and to assess whether zinc replacement is an effective therapy for BMS. Methods: Serum zinc level was evaluated in 276 patients with BMS. To assess the therapeutic effect of zinc replacement, patients with zinc deficiency were administered a zinc supplement (14.1 mg/day). Pain intensity 6 months after zinc replacement was evaluated using an 11-point numerical scale. We also developed an animal model of zinc deficiency to assess the effects of zinc deficiency on the oral mucosa. Results: Of the 276 patients with BMS, 74 (26.8%) had low serum zinc levels. Zinc replacement therapy lowered the mean numerical pain scale in these patients from 8.1 to 4.1, compared with a mean decrease from 7.7 to 6.7 in a control group (P = 0.004). In our animal model of zinc deficiency, the main pathologic findings were hyperkeratinization and increased mitosis on the dorsum of the tongue, although there were no gross oral mucosal lesions. Conclusions: Zinc deficiency might play a role in some patients with BMS. In such patients, appropriate zinc replacement therapy is effective in relieving symptoms.