Is silica beneficial for hair?

The silica (bioavailable silicon dioxide) is increasingly used as an active ingredient in dietary supplements designed to improve hair appearance. Several scientific studies support its beneficial effects, particularly regarding the strength, elasticity, and thickness of hair fibers. Polymerized forms, such as the silica colloidal or mineral silica are very poorly absorbed by the body, unlike monomeric forms. Among the most studied forms, choline-stabilized orthosilicic acid (ch-OSA) stands out for its good intestinal absorption and stability in solution.

A benchmark, randomized, double-blind, placebo-controlled clinical trial was conducted on 48 women with fine hair. Over 9 months, half of the participants received a daily supplementation of 10 mg of silicon in the form of ch-OSA, while the other half received a placebo. The results showed a significant improvement in several hair parameters in the treated group: the hair thickness (measured by fiber cross-sectional area) increased by 12.8%, compared to no notable change in the placebo group. Furthermore, the tensile strength (break load) was better preserved: a decrease of only 2.2% in the ch-OSA group versus 10.8% in the placebo group, representing a net gain of 13.1%. In addition, the elasticity (measured by the elastic modulus) decreased less in the supplemented group (−4.52% versus −11.9%), reflecting a greater maintenance of hair suppleness.

Another pilot study involving 34 volunteers divided into three groups (placebo, M-OSA, and MMST) demonstrated after 150 days of supplementation subjective improvements in hair texture, increased shine, and favorable effects on eyelashes and nails, although quantitative data were limited.

Despite these encouraging findings, certain limitations must be considered. The available studies are small-scale and often funded by supplement manufacturers, which may introduce bias.

Furthermore, the majority of observed benefits relate to the quality of existing hair (strength, shine, thickness), with no solid evidence of an effect on regrowth or growth stimulation, and involving oral supplementation rather than topical application.

The effect of silica is gradual: clinical studies show efficacy after several months of continuous supplementation (usually between 5 and 9 months). Before starting a regimen, it is recommended to consult a healthcare professional, especially if you are on medication or have chronic health conditions.

The silica is a commonly used ingredient in hair care products, both in topical cosmetics and as a dietary supplement. It is valued for its fortifying properties on the hair fiber, its ability to enhance shine, limit breakage, and, in some cases, support improved hair quality. It is available in various forms depending on the product type, each offering specific effects.

In dietary supplements, silica is present in bioavailable forms such as choline-stabilized orthosilicic acid (ch-OSA), scientifically recognized for its positive effects on hair thickness and strength. Other supplements include silica derived from silicon-rich plants such as bamboo extract or horsetail, often paired with other actives like biotin, zinc, or vitamin B8 to reinforce hair action. These products are typically available as capsules, tablets, or drinkable solutions, to be taken over several months.

From the perspective of cosmetic products, silica is integrated into certain shampoos, conditioners, masks, or styling sprays. It appears on the INCI list under the names “Silica,” “Hydrated Silica,” or “Silica Silylate.” These forms, which are not absorbable by the skin, are used for their potential texturizing properties: they would add volume, absorb excess sebum, and enhance the texture of hair care formulations. In some cases, silica is also present as natural powders, like rhassoul (Moroccan clay) or Ayurvedic powders, which naturally contain silicon and are used to purify the scalp while strengthening the hair.