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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Mineral

Selenium

Likelihood in at-risk patientsLow

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

Evidence confidenceLow

Strength of the peer-reviewed evidence.

Food sources

Brazil nuts, Seafood, Meats, Grains

Typical intake: 55 mcg/day for most adults (RDA).

Upper limit: 400 mcg/day for adults.

Dental & oral effects of deficiency

No well-established oral-specific sign of deficiency on file.

Associated with deficiency

  • Cardiomyopathy / immune impairment: Muscle weakness, immune dysfunction, and rare cardiomyopathy (Keshan disease) from severe deficiency.

Dental & oral effects of surplus / excess

  • Garlic-odor breath (halitosis)

    A distinctive garlicky breath odor is a recognized early sign of selenium excess (selenosis), worth noting since it presents at the chairside as an unexplained breath complaint.

  • Metallic taste (selenium excess)

    Along with garlic breath, a metallic taste is an early warning sign of excess selenium intake.

    Clinical management: Ask patients reporting an unexplained metallic taste about supplements (including 'immune' or 'thyroid' blends and Brazil nuts) and advise review with their physician if intake is high.

  • Mottled teeth (chronic selenium excess)

    Chronic high selenium intake (selenosis) is associated with mottled teeth, alongside hair and nail loss or brittleness.

    Clinical management: If unexplained enamel mottling is seen with brittle nails or hair loss, ask about high-dose selenium supplements and refer for medical review.

General toxicity (not necessarily oral-specific)

  • Selenosis: Hair and nail brittleness/loss, GI upset, and nerve damage from chronic excess selenium, usually from over-supplementation.

Sources

  1. Selenium: 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 safety of commonly used vitamins and minerals. Moses G. Australian prescriber, 2021.