EFFECT OF ORAL INTAKE OF CHOLINE-STABILIZED ORTHOSILICIC ACID ON SKIN, NAILS AND HAIR IN WOMEN WITH PHOTODAMAGED SKIN

  1. Barel Æ M. Calomme Æ A. Timchenko K. De. Paepe Æ N. Demeester Æ V. Rogiers P. Clarys Æ D. Vanden Berghe Archives of Dermatology  Research  (2005) 297: 147–153

Abstract

Chronic exposure of the skin to sunlight causes damage to the underlying connective tissue with a loss of elasticity and firmness. Silicon (Si) was suggested to have an important function in the formation and maintenance of connective tissue. Choline-stabilized orthosilicic acid (‘‘ch-OSA’’) is a bioavailable form of silicon which was found to increase the hydroxyproline concentration inthe dermis of animals. The effect of ch-OSA on skin, nails and hair was investigated in a  randomized, double blind, placebo-controlled study. Fifty women with photodamaged facial skin were administered orally during 20 weeks, 10 mg Si/day in the form of ch-OSA pellets (n=25) or a placebo (n=25). Noninvasive methods were used to evaluate skin microrelief (forearm), hydration (forearm) and mechanical anisotropy (forehead). Volunteers evaluated on a virtual analog scale (VAS, ‘‘none=0, severe=3’’) brittleness of hair and nails. The serum Si concentration was significantly higher after a 20-week supplementation in subjects with ch-OSA compared to the placebo group. Skin roughness parameters increased in the placebo group (Rt:+8%; Rm: +11%; Rz: +6%) but decreased in the ch-OSA group (Rt: _16%; Rm: _19%; Rz: _8%). The change in roughness from baseline was significantly different between ch-OSA and placebo groups for Rt and Rm. The difference in longitudinal and lateral shear propagation time increased after 20 weeks in the placebo group but decreased in the ch-OSA group suggestingimprovement in isotropy of the skin. VAS scores for nail and hair brittleness were significantly lower after 20 weeks in the ch-OSA group compared to baseline scores. Oral intake of ch-OSA during the 20 weeks results in a significant positive effect on skin surface and skin mechanical properties, and on brittleness of hair and nails.

Introduction

Healthy skin impedes the penetration of microorganisms which can cause infections and protects against irritants. Ageing leads to several changes in the skin and its appendages (hair, nails). These changes can be broadly categorized as either intrinsic ageing (chronobiological)or photoageing (actinic ageing). Intrinsic ageing results in subtle but important alterations of cutaneous function that are presumed to be due to time alone, whereas photoageing is the result of preventable chronic exposure to ultraviolet (UV) radiation superimposed on intrinsic ageing. Major changes of photoageing occur in the dermis. A marked decrease in collagen, glycosaminoglycans and proteoglycans is observed combined with a degeneration of elastic fibers (elastosis) resulting in a rough leathery skin surface with fine and coarse wrinkles. Furthermore, a loss of elasticity and an increase in mechanical anisotropy of the skin is observed. Premature ageing of the skin due to excessive exposure to UV light either from the sun or/and from sun benches is an increasing problem [32]. Silicon (Si) is a ubiquitous element present in various tissues in the human body [1] and is present in 1–10 parts per million in hair [29] and nails [1]. Studies of silicon deprivation in growing animals indicated growth retardation and marked defects of bone and connective tissue [9]. Nutritional Si deficiency was found to decrease both the collagen synthesis and the formation of glycosaminoglycans in bone and cartilage [7]. In vitro, the activity of prolyl hydroxylase was reported to be dependent on the Si concentration in the medium of bone cultures, suggesting a Si-dependent pathway for collagen type I synthesis [8]. Others have suggested a structural role of Si in the cross-linking of glycosaminoglycans in connective tissue [25]. Recent animal studies confirm the involvement of Si in bone metabolism both in young animals [26, 27] and in models for postmenopausal osteoporosis [15, 24]. Subcutaneously implanted sponges of Si-deprived rats were found to contain less hydroxyproline compared to rats on a normal diet indicating that Si deprivation decreases collagen formation which is associated with wound healing [28]. In addition, the activity of liver ornithine aminotransferase, an important enzyme in the pathway of collagen formation, was lower in Si-deprived rats compared to Si-adequate rats [28]. Soluble Si is present as orthosilicic acid (OSA) in beverages and water. It is stable in dilute concentrations (<10_4 M) but polymerizes at higher concentrations around neutral pH into a range of silica species. Absorption studies indicated that only OSA is bioavailable, whereas its polymers are not absorbed [16]. Dietary silicates undergo hydrolysis, forming OSA which is readily absorbed in the gastrointestinal tract. Physiological concentrations of OSA stimulate skin fibroblasts to secrete collagen type I [23]. A stabilized form of OSA, choline-stabilized OSA (‘‘ch-OSA’’), was found to have a high bioavailability in humans compared to other Si supplements that contain polymerized forms of OSA [3, 33]. Supplementation of animals with low doses of ch-OSA resulted in a higher collagen concentration in the skin [5] and in an increased femoral bone density [4, 6]. Choline, the stabilizing agent in ch-OSA, is classified by the Food and Nutrition Board as an essential nutrient [12]. Although humans can synthesize it in small amounts, dietary sources are needed to maintain normal health [2]. Choline is important for the structural integrity of cellular membranes since it is the precursor of phospholipids (phosphatidylcholine and sphingomyelin) which are essential components of biological membranes. One of its metabolites, betaine, participates in the methylation of homocysteine to form methionine. Betaine is also known as an essential intracellular osmolyte [35]. Choline directly affects nerve signaling (as a precursor of the neurotransmitter acetylcholine), cell signaling (as a precursor for intracellular messengers such as diacylglycerol or ceramide, platelet-activating factor and sphingosylphosphorylcholine) and lipid transport/metabolism (required in the biosynthesis of very low-density lipoproteins). In the present study we investigated the effect of oral intake of ch-OSA on skin, hair and nails in a randomized, placebo-controlled double-blind study in subjects with photo-aged facial skin. READ ORIGINAL ARTICLE