Silicic acid is a source of bioavailable silicon, an element that has attracted scientific interest for its role in connective tissue health, including skin, hair, and nails. Several small-scale clinical studies have explored the relationship between silicon supplementation (often in the form of orthosilicic acid or choline-stabilized orthosilicic acid) and hair health. One of the more frequently cited studies is a randomized, placebo-controlled trial showing that women with thin hair who took 10 mg of silicon daily for 9 months experienced increased hair tensile strength and thickness compared to placebo (Arch Dermatol Res 2007;299:499-505). The proposed mechanism involves silicon's role in the synthesis of collagen and glycosaminoglycans, as well as in the structural integrity of hair fibers. However, the number of rigorous studies is limited, sample sizes are generally small, and there is a lack of large, multi-center clinical trials. Furthermore, not all studies have found significant effects, and the optimal form and dosage of silicon for hair health remain unclear. Thus, while there is preliminary scientific evidence suggesting a possible benefit, the overall quality and quantity of evidence supporting the use of silicic acid for hair loss or thinning is modest. It is not a mainstream or first-line treatment, but may be used as a supplement with some scientific backing.