Which active ingredient combinations are beneficial when used with silica?

In cosmetics, the combination of clay and silica could form an interesting synergy, although it remains scarcely documented by scientific studies to date. This combination relies on complementary physicochemical mechanisms and on empirical observations drawn from numerous existing formulations, particularly in masks, mattifying powders, or gentle exfoliants.

Clay, as a mineral raw material naturally rich in silica, offers a widely recognized ability to absorb sebum and adsorb impurities in skincare. It could unclog pores, remove excess sebum, and leave the skin clearer, while providing minerals that may help maintain good skin health.

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

Silica, added as a supplement in a clay-based formulation, would strengthen several aspects of a treatment’s sensory and technical performance. In micronized powder form, it would further mattify the skin thanks to its very fine absorbent power, while improving the product’s feel (the "soft-focus" effect). In colloidal form, it could play a stabilizing and structuring role in gels or creams containing clays, rendering the texture more homogeneous, smooth, and pleasant to apply. It is also assumed, based on certain silicon-related publications, that silica could support long-term skin firmness and elasticity by indirectly stimulating collagen synthesis, although these effects have been demonstrated primarily via oral intake rather than topical application.

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 thanks to the absorbent/adsorbent properties of clay, enhanced by the mattifying and texturizing effect of silica; then, potentially, a cutaneous support 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 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 utilize this combination in their products, which tends to confirm its practical utility. However, it should be emphasized 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 therefore represents a promising avenue, grounded in hypotheses derived from the individual properties of each ingredient, but it still requires validation through targeted dermatological studies.

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

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

For example, a study published in American Journal of Clinical Nutrition demonstrated 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. Likewise, a 2012 study in Journal of Investigative Dermatology noted enhancements in hair strength and skin elasticity following silicon ingestion. However, these beneficial effects on collagen primarily relate to oral supplementation.

In topical application, no direct clinical study to date has demonstrated an increase in collagen synthesis linked 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-solubilized form, making its direct biological efficacy in the dermis uncertain. Nonetheless, some hypotheses have been proposed about the indirect potential of topical silica to support skin structure. For example, by forming a thin film on the skin’s surface, it could temporarily improve texture, smooth fine lines, and reduce the visual appearance of skin aging (soft-focus effect). In addition, formulations enriched with colloidal silica could help hydrate and protect the skin surface, which contributes to maintaining an environment favorable to dermal regeneration, although this does not necessarily imply direct collagen stimulation.

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

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

It therefore represents an interesting line of investigation, grounded in plausible biochemical foundations, but it requires targeted clinical research to be confirmed in a cosmetic context.

Excess sebum is one of the main factors responsible for skin shine, as well as the appearance of blackheads and other imperfections. For mixed to oily skin, combining active ingredients capable of both regulating sebum production and improving skin appearance may be of interest. It is in this context that the combination of microporous silica and bakuchiol is generating growing interest in cosmetics.

Thanks to its very small pore diameter, microporous silica acts as a "lipid trap." It absorbs excess sebum from the skin’s surface without drying it out, delivering an instant mattifying effect and a uniform finish. With regard to the bakuchiol, it exhibits several mechanisms of action relevant to skin prone to hyperseborrhea. Studies in vitro have shown that it can reduce the activity of 5α‐reductase, an enzyme involved in sebum overproduction. In parallel, its antioxidant action protects sebum from lipid peroxidation, limiting comedone formation. Finally, the bakuchiol targets Cutibacterium acnes, the bacterium that proliferates in sebum and contributes to inflammatory blemishes.

By combining microporous silica and bakuchiol, one achieves an immediate mattifying action along with deeper regulation of the mechanisms involved in excess sebum. This dual approach is particularly relevant for oily, acne-prone skin. However, it is important to emphasize that, to date, no clinical study has demonstrated true synergy between these two active ingredients. One can nevertheless regard their association as complementary and coherent in a formulation designed to reduce shine and improve skin balance.

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