Clinical decision-support only. For use by licensed dental professionals. Not a substitute for professional judgment or a complete drug reference. Always verify with primary sources.
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Vitamin

Vitamin B3 (Niacin)

Likelihood in at-risk patientsLow

Likelihood of deficiency within an at-risk group, not the general population.

Evidence confidenceModerate

Strength of the peer-reviewed evidence.

Food sources

Poultry, Fish, Peanuts, Enriched grains

Typical intake: 16 mg/day for men, 14 mg/day for women (RDA).

Upper limit: 35 mg/day (from supplements/fortified foods) for adults.

Dental & oral effects of deficiency

  • Dry mouth (xerostomia)

    Niacin deficiency is specifically associated with dry mouth, distinct from the more common medication-related causes.

  • Bright red, swollen tongue (glossitis)

    Bright red, swollen tongue is a feature of pellagra.

  • Cracked lips and mouth sores (cheilitis and stomatitis of pellagra)

    Pellagra causes mucosal involvement beyond the tongue, including cheilitis, oral ulceration/erosions, and unpleasant breath.

    Clinical management: Consider niacin deficiency with glossitis plus mouth sores and a sun-exposed rash, particularly with alcohol use disorder, malabsorption or isoniazid therapy; refer for medical assessment and keep oral care gentle.

Associated with deficiency

  • Pellagra: Classic triad of dermatitis, diarrhea, and dementia from severe niacin deficiency.

Dental & oral effects of surplus / excess

No well-established oral-specific effect of excess intake on file.

General toxicity (not necessarily oral-specific)

  • Niacin flush / liver toxicity: Skin flushing at moderate excess doses; liver toxicity at sustained high doses.

Sources

  1. Niacin: Health Professional Fact Sheet. National Institutes of Health, Office of Dietary Supplements. NIH Office of Dietary Supplements, 2026.
  2. A Prescription for Change: Food as Medicine & the Vital Role of Nutrition in Patient Care. teethFirst. Continuing education course material, 2025.
  3. The Impact of Vitamin Deficiencies on Oral Manifestations in Children. Lešić S, Ivanišević Z, Špiljak B et al. Dentistry journal, 2024.
  4. Cutaneous signs of nutritional disorders. Wong CY, Chu DH. International journal of women's dermatology, 2021.