How Nutrient Deficiencies Impact the Oral Mucosa and How to Manage Them: A Narrative Review.

BACKGROUND: Malnutrition and micronutrient deficiencies may impact the oral mucosa even before any other symptoms become clinically obvious. This makes the oral cavity an important site for early detection of nutritional imbalance. Across the literature review, the most documented vitamin is vitamin B12. Other widely reported nutrients are iron, folate, and zinc. Less consistently documented are vitamins A, C, and D. Their correlation with recurrent aphthous stomatitis (RAS), atrophic glossitis, angular cheilitis, burning mouth symptoms (BMS), mucosal erythema, and oral candidiasis (OC) is brought to light. This review collects evidence on how nutritional deficiencies influence epithelial turnover, immune competence, oxidative balance, and mucosal repair to understand the pathogenesis of oral mucosal diseases. METHODS: This narrative review draws on literature searches of major databases using terms related to malnutrition, nutritional deficiencies, and oral mucosal diseases. RESULTS: The evidence is strongest for RAS and atrophic glossitis, where several observational studies and recent systematic reviews associate hematinic deficiencies with disease presence and, in some cases, symptom improvement after performing replacement therapy. Zinc deficiency has also been linked to recurrent ulceration, burning mouth syndrome, and epithelial alterations, while vitamin B12 deficiency may present with glossitis, BMS, angular cheilitis, mucosal ulceration, and lingual linear lesions even with the absence of systemic anemia. Oral candidiasis is more common in malnourished patients due to reduced host resistance and diminished salivary protection, especially in older or medically compromised patients. CONCLUSIONS: Although causality cannot be assumed from all included studies, the literature suggests that unexplained oral mucosal lesions, especially when they are multiple or persistent, warrant nutritional screening as part of a comprehensive oral medicine assessment.