What beneficial combinations of active ingredients can be used with silica?

In cosmetics, the combination of clay and silica could constitute an interesting synergy, although little documented by scientific studies to date. This combination is based on complementary physico-chemical mechanisms and on empirical observations derived from numerous existing formulations, notably 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 skin care. It could unclog pores, eliminate excess sebum and leave the skin clearer, while supplying minerals that can help maintain healthy skin.

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

Silica, added as an adjunct to a clay-based formula, would reinforce various aspects of the treatment’s sensory and technical performance. In micronised powder form, it would help to mattify the skin more effectively thanks to its ultra-fine absorbent properties, while improving the product’s feel (a “soft-focus” effect). In colloidal form, it could play a stabilising and structuring role in gels or creams containing clays, resulting in a more uniform, smooth texture that is pleasant to apply. It is also hypothesised, based on certain silicon-related publications, that silica may support skin firmness and elasticity in the longer term by indirectly stimulating collagen synthesis, although these effects have been demonstrated primarily via oral administration rather than topically.

The hypothesis of a synergy between clay and silica is therefore based on the idea of a multi-stage action: first an immediate skin purification thanks to the absorbent/adsorbent properties 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 creation of textures that are more pleasant, less drying and more aesthetically pleasing than clay alone, which can sometimes tug or crack as it dries on the skin.

Some cosmetic brands are already harnessing this combination in their products, which suggests its practical utility. 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 therefore represents a promising avenue, based on hypotheses formulated from the individual properties of each ingredient, but which should be validated by targeted dermatological studies.

The relationship between silica and collagen synthesis has attracted growing interest, although it remains predominantly explored in the context of oral supplementation rather than topical use. 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, the 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 in the form of silicates or monomethylsilanetriol (MMST), can 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 enhancement in hair strength and skin elasticity after silicon ingestion. However, these beneficial effects on collagen primarily relate to oral supplementation.

When applied topically, no direct clinical study to date has demonstrated any increase in collagen synthesis attributable to the presence of silica in a formulation. The skin barrier strongly limits the absorption of mineral silica, especially in its insoluble amorphous form, which renders its direct biological efficacy in the dermis uncertain. Nevertheless, 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 may temporarily improve texture, smooth fine lines and reduce the visual perception of skin ageing (soft-focus effect). Moreover, formulations enriched with colloidal silica could contribute to hydrating and protecting the skin surface, which contributes to maintaining an environment favourable for dermal regeneration, although this does not necessarily involve direct stimulation of collagen.

If the role of silicon in collagen synthesis is supported by several scientific studies in oral supplementation, the topical use of silica 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.

Thus, this approach presents an interesting prospect, grounded in plausible biochemical mechanisms, but it requires targeted clinical research to be validated in a cosmetic context.

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

Due to its very small-pore structure, microporous silica functions as a 'lipid trap'. It captures excess sebum on the skin’s surface without drying it out, achieving an instant mattifying effect and an even finish. Regarding the bakuchiol, it exhibits multiple mechanisms of action pertinent to skin prone to hyperseborrhoea. Studies in vitro have shown that it can reduce 5α-reductase activity, an enzyme involved in sebum overproduction. Concurrently, its antioxidant action protects sebum from lipid peroxidation, thereby 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 alongside a deeper regulation of the mechanisms involved in excess sebum. This dual approach is particularly pertinent for oily, acne-prone skin. However, it is important to emphasise that, to date, no clinical trial has demonstrated a true synergy between these two active ingredients. One may nevertheless consider their association as complementary and coherent in a formula designed to reduce shine and improve skin balance.

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