Silica, a compound containing silicon, is sometimes included in supplements aimed at supporting nail health. The scientific justification stems from the role of silicon in connective tissue formation and the synthesis of collagen, which is a structural protein found in nails, skin, and hair. Some observational and small-scale clinical studies have suggested that dietary silicon may contribute to the strength and quality of nails, possibly by supporting keratin structure. For example, a study published in 2007 demonstrated improvements in the brittleness of nails in women taking an orthosilicic acid supplement, a bioavailable form of silica. However, the overall body of evidence is limited, with few well-powered, randomized controlled trials. The available data suggest a potential benefit, but the effect size and clinical relevance remain uncertain. Most major reviews and authoritative bodies consider the evidence as preliminary and call for more rigorous research to establish a clear link between silica supplementation and improved nail health. In summary, while there is some scientific rationale and limited empirical support for silica's role in nail health, the evidence is not robust, and silica supplementation for this purpose should be considered with caution.