Silicon yeast is a dietary supplement made by enriching yeast (typically Saccharomyces cerevisiae) with the mineral silicon, usually in the form of orthosilicic acid. Silicon is an essential trace element involved in the synthesis and stabilization of connective tissue components, including collagen and glycosaminoglycans. Several scientific studies have investigated the role of silicon, particularly in its bioavailable forms, in supporting hair, skin, and nail health. For hair, silicon is thought to contribute to structural integrity and growth by participating in the formation of keratin, the main protein in hair fibers.

A few human clinical studies have shown that supplementation with bioavailable silicon, such as choline-stabilized orthosilicic acid (not always specifically silicon yeast), may improve hair tensile strength and thickness, as well as reduce hair fragility. Silicon yeast is used as a source of bioavailable silicon in some dietary supplements, and its safety profile is generally considered favorable. However, the number of high-quality, peer-reviewed studies specifically on silicon yeast and hair health is limited; most evidence is extrapolated from studies of other silicon forms. As such, while there is a reasonable scientific rationale and some supportive data, the overall evidence for silicon yeast specifically supporting the hair body system is moderate but not robust.