12 Surprising Causes of Spoon-Shaped Nails (Koilonychia)

8. Celiac Disease

Celiac disease, an autoimmune disorder triggered by gluten ingestion, can indirectly cause koilonychia. This condition damages the lining of the small intestine, impairing the absorption of essential nutrients such as iron, zinc, and B vitamins. The resulting nutrient deficiencies, particularly iron deficiency anemia, are strongly associated with spoon-shaped nails. Other symptoms of celiac disease include gastrointestinal discomfort, fatigue, and skin rashes. For patients with celiac disease, adhering to a strict gluten-free diet is critical to restoring nutrient levels and promoting overall health, which can improve the appearance of the nails.