Which combinations of active ingredients are beneficial with silica?

In cosmetics, the combination of clay and silica could represent an intriguing synergy, although it is scarcely documented by scientific studies to date. This pairing relies on complementary physico-chemical mechanisms and on empirical observations drawn from numerous existing formulations, particularly in masks, mattifying powders or gentle exfoliants.

Clay, as a naturally silica-rich mineral raw material, offers a widely recognised capacity to absorb sebum and adsorb impurities in skincare. It can help to unclog pores, remove excess sebum and leave the skin clearer, while supplying minerals that may contribute to maintaining good skin health.

However, these effects remain predominantly described on the basis of traditional use rather than on robust clinical evidence.

The silica, when added as a supplement in a clay-based formulation, would enhance several aspects of the sensory and technical efficacy of the treatment. As a micronised powder, it would help mattify further mattifying the skin thanks to its very fine absorbent power, while improving the product’s feel (‘soft-focus’ effect). In colloidal form, it could play a stabilising and structuring role in gels or creams containing clays, making the texture more homogeneous, smooth and pleasant to apply. It is also hypothesised, based on certain publications on silicon, that silica could support in the longer term the firmness and skin elasticity by indirectly stimulating collagen synthesis, although these effects have essentially been demonstrated orally rather than topically.

The hypothesis of a synergy between clay and silica thus rests on the idea of a multi-step action: first an immediate purification of the skin through the absorbent/adsorbent action of clay, reinforced by the mattifying and texturising effect of silica; then, potentially, a skin-supporting effect via the contribution of silicon to tissue regeneration and to the quality of the extracellular matrix. From a formulation standpoint, this combination would also allow for the design of textures that are more pleasant, less drying and more aesthetically pleasing than with clay alone, which can sometimes tug or crack as it dries on the skin.

Some cosmetic brands already employ this combination in their products, which tends to confirm its practical merits. However, it should be emphasised that to date no comparative clinical study has demonstrated that a formulation combining clay and silica is more effective than a treatment containing only one of the two components.

This is therefore a promising avenue, based on hypotheses formulated from the individual properties of each ingredient, but which would benefit from validation through targeted dermatological studies.

The relationship between silica and collagen synthesis is attracting growing interest, although it is still predominantly explored in the context of oral supplementation rather than topical application. Collagen is an essential structural protein responsible for the skin’s firmness, elasticity and cohesion. It is well established that its production decreases with age, contributing to the appearance of wrinkles, loss of skin tone and skin dehydration.

Silicon, an element naturally present in silica, is involved in the biosynthesis of collagen and glycosaminoglycans in connective tissues. Some studies have shown that organic silicon, when administered orally as silicates or monomethylsilanetriol (MMST), could stimulate collagen production and enhance dermal density.

For example, a study published in American Journal of Clinical Nutrition highlighted a correlation between silicon intake and improved bone and skin health, suggesting that silicon may act as a cofactor in the enzymatic steps of collagen synthesis. Similarly, a study published in 2012 in Journal of Investigative Dermatology observed an improvement in hair tensile strength and skin elasticity following silicon ingestion. However, these beneficial effects on collagen primarily pertain to oral supplementation.

When applied topically, no direct clinical study to date has demonstrated an increase in collagen synthesis due to the presence of silica in a formulation. The skin barrier strongly limits the absorption of mineral silica, especially when it is in an amorphous, non-solubilised form, which makes its direct biological efficacy in the dermis uncertain. However, certain hypotheses have been proposed regarding the indirect potential of topical silica to support skin structure. For example, by forming a thin film on the skin surface, it could temporarily improve texture, smooth fine lines and reduce the visual perception of skin ageing (soft-focus effect). Moreover, formulations enriched with colloidal silica could help to hydrate and protect the skin surface, thereby contributing to the maintenance of an environment favourable to dermal regeneration, although this does not necessarily imply direct stimulation of collagen.

If the role of silicon in collagen synthesis is supported by several scientific studies on oral supplementation, the use of silica in topical application relies more on mechanical and sensory hypotheses than on direct biological evidence.

To date, no study has demonstrated that the topical application of silica to the skin stimulates collagen production in vivo.

This therefore represents an interesting avenue, underpinned by a plausible biochemical rationale, but it requires targeted clinical studies to be confirmed in a cosmetic context.

• JUGDAOHSINGH R. Silicon and bone health. Journal Nutrition Health Aging (2009).

• BAREL E. & al. Use of silicon for skin and hair care: an approach of chemical forms available and efficacy. Anals Brasileiros de Dermatologia (2016).

• CHAVES C. & al. Evaluation of cutaneous rejuvenation associated with the use of ortho-silicic acid stabilized by hydrolyzed marine collagen. Journal of Cosmetic Dermatology (2018).

• SAHIN K. & al. Effects of a combination of arginine silicate inositol complex and a novel form of biotin on hair and nail growth in a rodent model. Biological Trace Element Research (2022).

• ABDOU E.M. & al. Duo photoprotective effect via silica-coated zinc oxide nanoparticles and vitamin C nanovesicles composites. Pharmaceutical Research (2024).