Related Technical Articles
The beauty market is looking for the latest solutions to combat universal hair issues, such as breakage, thinning, and dryness. With the increasing awareness of ingredients among consumers, the demand for scientifically proven hair care solutions has increased significantly. The global market for hair growth supplements market is expected to grow at a compound annual growth rate (CAGR) of 15.5% from 2025 to 2030. Among the recently emerging trace elements gaining attention for their benefits to hair health, silicon in its bioavailable form as orthosilicic acid (OSA), has been of particular interest to researchers and product formulators.
Compared to other silicon forms that are difficult for the human body to use efficiently, OSA can be readily absorbed and incorporated into biological structures. It makes OSA useful for both topical and dietary usage. Read on to learn more about OSA in hair health, its chemical properties, mechanisms of action and clinical efficacy.
Chemistry and Bioavailability of Orthosilicic Acid
Orthosilicic acid (H₄SiO₄) has a simple chemical makeup with just one silicon atom attached to four hydroxyls as seen in Fig.1. This type of molecular arrangement endows orthosilicic acid with impressive features, including high water solubility and high bioavailability compared to other silicon compounds. As a neutral molecule at physiological pH, orthosilicic acid has a high permeability through cell membranes.
Comparison with Other Silicon Forms
Compared to other forms of silicon found in cosmetics and foods, the differences in bioavailability are readily apparent. Silicates, colloidal silica, and silicon dioxide, most of which are found in many products, accommodate suboptimal rates of absorption, much of which leaves the body without being metabolised. Studies show that only 5% or less of these non-OSA forms reach bioavailability, compared to OSA, which has absorption rates of 50-70% when formulated correctly.
Stability and Formulation Challenges
The biggest challenge of OSA is its inherent instability. In dense solutions, OSA molecules rapidly polymerise to form silica gel, which drastically reduces bioavailability. This instability presents formulation challenges for product developers who want to incorporate active OSA into their products.
Bioavailability in Dietary and Topical Forms
Choline-stabilised OSA (ch-OSA) has been identified as a highly effective formulation, as the choline addition avoids polymerisation while ensuring bioavailability. Other stabilisation techniques involve proprietary pH buffers and co-factors that ensure OSA remains in its monomeric, bioactive form.
When consumed orally, ch-OSA is absorbed through the small intestine into the bloodstream, where it is transported to various tissues, such as the scalp and hair follicles. In topical applications, delivering bioavailable OSA effectively to deeper skin layers and hair follicles presents a challenge due to the skin’s natural barrier. To overcome this, formulations often incorporate transdermal penetration enhancers such as liposomes, nanoemulsions or phospholipid complexes.
The Biological Role of Silicon in Hair Physiology
As the third most common trace element in the human body, silicon is responsible for the development and maintenance of connective tissue, particularly in collagen-rich and glycosaminoglycan-rich tissues.
Role in Connective Tissue and Keratin Production
Silicon cross-links hair structural proteins and glycosaminoglycans, which increases the total structural strength of hair fibres. Silicon is also involved in keratinisation, which strengthens the protein network that forms the hair shaft. Moreover, adequate silicon concentrations are correlated with greater tensile strength and elasticity in hair fibres.
Contribution to Structural Integrity
In addition to the hair shaft, silicon influences scalp health by supporting collagen production in the dermal layer where hair follicles reside. Studies demonstrate that silicon deficiency is frequently linked to reduced collagen synthesis and skin barrier dysfunction, both of which can negatively affect hair growth and retention.
Role in Follicular Health and Hair Anchorage
The extracellular matrix (ECM), which consists primarily of collagen and elastin fibres, maintains the stability of hair follicles in scalp tissue. Silicon preserves the structural integrity of this matrix, thereby potentially enhancing hair anchorage and avoiding hair loss caused by poor follicular attachment. Notably, studies have indicated that silicon content in hair fibres decreases with age and environmental stress, which may be the cause of age-related hair thinning and decreased hair quality. Therefore, supplementation is more popular among the ageing population.
Mechanisms of Action in Hair Health
OSA affects hair health by several interlinked mechanisms. One of the key mechanisms is the induction of collagen production in the hair follicular microenvironment. The entire mechanism of action of OSA for hair health is depicted in Fig.2
Fig.2 Mechanism of Action in Hair Health
Collagen Support and Glycosaminoglycan Production
Improvement of Hair Thickness and Elasticity
Scalp Barrier Support and Hydration
Antioxidant and Anti-inflammatory Properties
Delivery Methods for OSA in Hair Care Products
The effectiveness of OSA relies heavily on how it is delivered. Topical applications and oral supplements both have special benefits, but they need different formulations and have different effectiveness levels, as explained in Table 1
Table 1. Key Characteristics of OSA Delivery Systems in Hair Care Products
| Delivery Form | Type | Key Details |
| Topical Applications | Shampoos and Conditioners | Stabilized OSA (0.5-3%) with humectants, strengthens hair fibers and hydrates the scalp. |
| Serums and Scalp Treatments | Up to 5% stabilized OSA; leave-in formulas; deeper follicle penetration for targeted repair. | |
| Products with Penetration Enhancers | Liposomes, nanoemulsions and phospholipid carriers enhance delivery to follicles. | |
| Oral Supplements | Choline-Stabilized OSA (ch-OSA) | Highly bioavailable; absorbed through the GI tract; improves hair strength, reduces breakage. |
| Formulas with Synergistic Nutrients | Combined with biotin, zinc and vitamin C. Supports keratin production, collagen synthesis, and scalp health. |
Clinical Evidence and Effectiveness
Scientific literature concerning the effects of OSA on hair health consists of both clinical trials and in vitro studies, with generally positive results on different parameters of hair growth and quality.
In Vitro and Laboratory Research
Hair Strength and Breakage Reduction
Human clinical trials of oral and topical OSA supplementation have shown a number of positive outcomes. In a double-blind, placebo-controlled trial involving 48 women with fine hair, daily supplementation with 10 mg of ch-OSA for 9 months increased hair thickness by about 12.8% over the placebo. Break load parameters (breakage resistance) increased by a mean of 13.7%.
Improvement in Thickness and Shine
Dosage and Treatment Duration
Formulation and Stability Considerations
Stability in Aqueous Solutions and Emulsions
Compatibility with Common Cosmetic Ingredients
OSA has inconsistent compatibility with many typical cosmetic ingredients. Multivalent cations at high concentrations, some preservative systems, and strong chelating agents can significantly enhance the polymerisation of OSA. Thus, stability tests should be done carefully by formulators to confirm product performance for the anticipated shelf life.
Encapsulation and Delivery Systems
Safety and Regulatory Aspects
Regulatory Status in Cosmetic and Nutraceutical Applications
Regulatory status varies somewhat in international markets. Stabilised OSA is authorised in the European Union as a food supplement under Regulation (EC) No 1170/2009 with some provisions for claims for hair, skin and nail health. The US FDA classifies OSA as a Generally Recognised as Safe (GRAS) nutritional supplement, and some stabilised forms have FDA clearance for specific cosmetic uses.
Labeling Considerations and Allowed Claims
Long-term Use and Tolerability
Long-term safety trials demonstrate excellent tolerability with both topical and oral OSA when used as directed. Recommended standard dosages (5-10 mg silicon daily from oral supplements) remain far below the estimated safe upper intake level of 700-1,500 mg/day set by such regulatory agencies.
Market Potential and Future Outlook!
Orthosilicic acid has a special place in the contemporary hair care market, with science-backed benefits of structural strength and appearance. Cumulative evidence demonstrates its efficacy when well-formulated for stability and bioavailability. Driven by a commitment to holistic wellness, consumers are choosing products that feature active ingredients with scientifically proven benefits. OSA is well-positioned to capitalize on this trend. The scientific evidence supporting OSA continues to grow, with both laboratory studies and clinical trials confirming its efficacy across multiple parameters of hair health and appearance. This evidence-based approach positions OSA as a legitimate functional ingredient rather than merely a marketing claim.
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