Iron is scientifically validated as important for supporting the health of the nails. Iron deficiency is a well-established cause of brittle nails and a specific nail abnormality called koilonychia (spoon-shaped nails). Numerous clinical and observational studies have shown that iron deficiency anemia frequently presents with changes in nail morphology, including thinning, brittleness, and altered shape. These changes are believed to occur because iron is essential for hemoglobin production and oxygen transport, which are necessary for the growth and maintenance of healthy nail tissue.

Restoring normal iron levels through supplementation or dietary changes has been shown to reverse nail abnormalities associated with deficiency. The scientific literature, including dermatology and hematology references, routinely lists nail changes as a clinical sign of iron deficiency, further supporting the link. However, in individuals without iron deficiency, additional iron supplementation is not shown to further benefit nail health and may carry risks.

In summary, the use of iron to support nail health is scientifically justified, but specifically in the context of iron deficiency. There is strong evidence (rated 4 out of 5) that correcting iron deficiency can improve nail health, while supplementation beyond normal levels does not provide added benefit for nails.