Mineral blends, typically containing essential minerals such as zinc, selenium, silicon, iron, copper, and calcium, are justified by scientific evidence for supporting nail health. Nails require several micronutrients for proper growth and strength, and deficiencies in certain minerals often manifest as brittle, weak, or misshapen nails.

Zinc is well-documented in clinical studies to play a crucial role in keratin production, the protein that makes up nails. Zinc deficiency can cause white spots, slow growth, and increased fragility. Iron deficiency is another common cause of nail abnormalities, such as spoon-shaped nails (koilonychia). Silicon (often provided as orthosilicic acid) has shown in some randomized controlled trials to improve nail strength and reduce brittleness.

Selenium and copper are trace elements involved in antioxidant protection and cross-linking of keratin, respectively, both of which are important for healthy nail structure. Calcium is often included, although its role in the nail matrix is less critical than in bone, but it may still contribute to overall nail integrity.

Overall, there is moderate to strong scientific evidence (rating 4) supporting the use of mineral blends to address deficiencies and promote normal nail health, particularly in populations at risk of micronutrient insufficiency. However, supplementation is most effective when correcting a documented deficiency, rather than for generalized enhancement in individuals with already adequate mineral intake.