Mineral

Iron

Likelihood in at-risk patientsHigh

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

Evidence confidenceHigh

Strength of the peer-reviewed evidence.

Food sources

Red meat, Legumes and lentils, Fortified cereals, Dark leafy greens (with vitamin C to aid absorption)

Typical intake: 8–18 mg/day depending on age and sex (RDA); 27 mg/day in pregnancy.

Upper limit: 45 mg/day for adults.

Smooth, pale, sore tongue (atrophic glossitis)
Pale, smooth tongue with papillary loss.
Cracked, sore mouth corners (angular cheilitis)
Cracking at the mouth corners, often bilateral.
Pale oral mucosa
Generalized pallor of the gingiva and mucosa from reduced hemoglobin.
Recurring canker sores (recurrent aphthous ulcers)
Low iron stores (low ferritin) and low hemoglobin are more common in people with recurrent canker sores, and correcting the deficiency may reduce recurrences.
Clinical management: For a patient with frequent canker sores, ask about heavy periods, vegetarian/restricted diets, GI disease or known anemia, and recommend a physician check of blood count, ferritin, B12 and folate. Manage sores symptomatically (topical protective/anesthetic agents, avoid SLS toothpaste if it seems to trigger them).

Iron-deficiency anemia: Reduced oxygen-carrying capacity; fatigue, pallor.
Plummer-Vinson syndrome: Rare triad of iron-deficiency anemia, glossitis, and esophageal webs, a distinctive severe presentation.

Extrinsic tooth staining
Liquid iron supplements commonly cause dark staining on enamel with direct contact: advise diluting the dose, using a straw, and brushing after.
Gray-brown discoloration of gums or cheeks (mucosal pigmentation, rare)
Chronic iron overload (hemochromatosis) has been associated with rare gray-bronze mucosal or gingival pigmentation.

Hemochromatosis (iron overload): Organ damage (liver, heart, pancreas) from chronic excess iron, usually from a genetic predisposition or repeated transfusions rather than diet alone.