Clinical studies reveal cosmeceuticals' benefits.
AS ANTI-AGING PRODUCT CLAIMS grow bolder every day, marketers face challenges from public health and government agencies, consumer and advertising watchdogs and competitors. Claims must be supported by objective biophysical tests that are combined with consumer perception, clinical, safety and toxicology studies. To avoid regulatory or legal action, it is advisable to support each claim. Biophysical methods usually adequately support performance claims, and while these evaluations have not been standardized, their results are usually accepted because they are based on sound scientific principles and hence, are considered adequate for supporting claims. These biophysical evaluations are further strengthened by clinical evaluations by trained technicians and dermatologists.
Many anti-aging products, both topical and oral, contain well-known actives to make their products effective and also attract consumer attention by making compelling marketing claims. This column will review several of these actives as well as information on recent clinical studies. Marketers planning to conduct clinical trials should note that the typical clinical trial is double-blind and randomized. This method prevents the introduction of bias by dermatologists, patients and any other external influences.
Alpha Lipoic Acid
This potent, stable antioxidant is soluble in lipids and water and can be absorbed percutaneously. Researchers studied the effect of alpha lipoic acid (LA) on the protein collagen from high fructose-fed rat skin. (1) The rats were divided into four groups of six each. Two groups of rats were fed with a high fructose diet (60g/100g diet) and administered either LA or 0.2 ml saline placebo for 45 days. The other two groups were fed a control diet containing starch (60g/100g diet) and administered either saline or lipoic acid. The rats were maintained for 45 days. Plasma glucose, insulin, fructosamine, protein glycation, and blood glycated hemoglobin (HbA1C) were measured. Collagen was isolated from the skin and the physicochemical properties of collagen were studied. Fructose administration caused accumulation of the collagen in the skin. Extensive cross-linking was evidenced by enhanced glycation and AGE-linked fluorescence. Increased peroxidation and change in physicochemical properties such as shrinkage temperature, aldehyde content, solubility pattern, susceptibility to denaturing agents were observed in fructose-fed rats. SDS gel pattern of collagen from these rats showed elevated beta component of type I collagen. These changes were alleviated by the simultaneous administration of LA. Administration of LA to fructose-fed rats had a positive influence on both quantitative and qualitative properties of collagen. The study results demonstrated that fructose diet-induced skin collagen abnormalities were prevented by alpha lipoic acid leading to delay in the onset of diabetic skin complications.
Vitamin C is essential for collagen biosynthesis. It functions as a co-factor for prolyl and lysyl hydroxylase, the enzymes responsible for stabilizing and cross-linking collagen. Topically applied vitamin C enhances collagen production in human skin. Researchers studied two unrelated individuals with Ehlers-Danlos syndrome type VI, which is characterized by congenital hypotonia, lax joints, severe kyphoscoliosis, friable skin and hemorrhagic hypotrophic scars. (2) The diagnosis was confirmed by decreased hydroxylysine residues in dermal collagen and decreased collagen lysl hydroxylase activity in their cultured skin fibroblasts. When patient 1 received oral sodium ascorbate (5g/d) for three weeks, ascorbate concentrations increased two-fold in plasma and 33-fold in urine. Urinary excretion of hydroxylysine and hydroxyproline increased during ascorbate administration. After one year, bleeding time, wound healing and muscle strength improved. Ascorbate supplementation (50 micrograms/mL) to confluent fibroblasts cultured from the two patients and controls increased hydroxyprolyl and hydroxylysyl residues of fibroblasts four- to seven- and three- to four-fold, respectively. Total protein associated with the cell layer increased 14% to 32% without concomitant change in cellular DNA. Total soluble collagenous material recovered from culture media increased 61% to 103% with ascorbate supplementation. This study demonstrated that ascorbate improves the clinical status of patients with impaired collagen lysyl hydroxylase activity by enhancing lysyl and prolyl hydroxylation and total collagen production.
Vitamin C & E Synergies Photo-damage of skin results in premature skin aging that is largely due to reactive oxygen species (ROS). In vivo antioxidants vitamin C and vitamin E were shown to provide an additional quenching effect of ROS. Furthermore, vitamin C helps increase skin firmness. It promotes synthesis of collagen I and III in human fibroblasts. Vitamin E is essential to maintain normal body metabolism and good health. It also protects skin from environmental damage. Vitamin E is absorbed through the epidermis. It is also absorbed through the pilosebaceous canal and the interior of the hair follicles. Vitamin E provides moisture and imparts smoothness and softening. In a clinical trial, researchers studied whether oral supplementation with vitamin E, vitamin C or vitamin E combined with vitamin C influenced the solar simulated radiation (SSR)-induced skin inflammation in healthy volunteers. (3)
The researchers investigated groups in a randomized, placebo-controlled study:
* Group 1: vitamin E 2g/day;
* Group 2: vitamin C 3g/day
* Group 3: vitamin E 2g/day combined with vitamin C 3g/day, and
* Group 4: placebo.
* Researchers analyzed vitamin E and vitamin C concentrations in keratinocytes prior to the study and 50 days after supplementation. The dose response curve of UV erythema was determined by reflectance spectrophotometry and the minimal erythema dose (MED) by visual grading before and after supplementation. Fifty days after supplementation, vitamin E and keratinocyte levels were increased in groups 1 and 3, and vitamin C concentrations were elevated in groups 2 and 3. The dose response curve of UVR induced erythema showed a significant flattening and the MED increased from 103+/-29 mJ/[cm.sup.2] (before supplementation) to 183+/-35 mJ/[cm.sup.2] (after supplementation) in group 3. There were no significant changes in groups 1 and 2 after vitamin supplementation. This study demonstrated that vitamin E and vitamin C act synergistically to reduce the sunburn reaction.
Vitamin A and E Synergies
Vitamin A as a skin nutrient is used to improve the appearance of skin and reduce wrinkles in anti-aging products. Studies have shown that topical vitamin A can be beneficial for the skin. In this study, researchers investigated two different antioxidant supplements composed of carotenoids, vitamin E and selenium on parameters related to skin health and skin aging. (4)
Thirty-nine volunteers with healthy, normal skin of skin type-2 were divided into three groups (n=13) and supplemented for a period of 12 weeks. Group 1 received a mixture of lycopene (3mg/day), lutein (3mg/day), beta-carotene (4.8 mg/day), alpha-tocopherol (10mg/day) and selenium (75microg/day). Group 2 was supplemented with a mixture of lycopene (6mg/day), beta-carotene (4.8mg/day), alpha-tocopherol (10mg/day) and selenium (75microg/day). Group 3 was the placebo control. Upon supplementation, serum levels of selected carotenoids increased in both groups. Skin density and thickness were determined by ultrasound measurements. A Surface Evaluation of Living Skin (Visioscan) determined skin roughness, scaling, smoothness and wrinkling. Study results demonstrated that roughness and scaling were improved by the supplementation with antioxidant micronutrients. In the placebo group, no changes were found for any of the parameters.
This material consists of polyphenols, including flavanoids, tannins and stibenes such as resevertrol. It has the most potent antioxidant, procyandins (also known as proanthocyanidins), leucocyanidins and condensed tannins. Grape seeds, waste products of the winery and grape juice industries, contain lipid, protein, carbohydrates and 5-8% polyphenols depending on the variety. Polyphenols in grape seeds are mainly flavanoids, including gallic acid, the monometric flavan-3-ols catachin, epicatechin, gallocatechin, epigallocatechin, and epicatechin 3-O-gallate, and procyanidin dimmers, trimers and more highly-polymerized procyanidins.
Grapeseed extract is a powerful antioxidant that protects the body from premature aging, disease and decay. Grape seeds contain mainly phenols such as proanthocyanidins (oligomeric proanthocyanidins). Researchers have shown that the antioxidant power of proanthocyanidins is 20 times greater than vitamin E and 50 times greater than vitamin C. (5)
Extensive research in this field suggests that grapeseed extract is beneficial in many areas of health because of its antioxidant effect to bind with collagen and promote youthful skin, cell health, elasticity and flexibility. Other studies have shown that proanthocyanidins help protect the body from sun damage and improve vision, flexibility, arteries and body tissues. Proanthocyanidins improve blood circulation by strengthening capillaries, arteries and veins. The most abundant phenolic compounds isolated from grape seed are catechins, epicatechin and procyanidin.
One of the most visible changes associated with the aging process in humans relates to a progressive thinning of the skin. Thinning results from a decline in glycosaminoglycans, as well as from changes in their chemical structure and three-dimensional organization. Researchers transdermally administered a mixture of antioxidants, alpha-lipoic acid (LA) (0.5%) and proanthocyanidin PA(0.3%) in a standard cosmetic vehicle base formulation supplemented with 2% benzyl alcohol as a penetration enhancer, a mixture of essential amino acids (0.2%). (6) Researchers found that this significantly enhanced collagen synthesis and deposition.
The amino acid mixture was designed to mimic serum concentrations, with supplemental methionine added to provide additional sulfur. The histological appearance of the skin of mature female rats treated in this fashion reflected the increased deposition of collagen in the dermis as well as thickened epidermal layer. The changes do not seem to be mediated by TGF- or PDGF, two growth factors known to stimulate collagen synthesis. Additionally researchers found that at lower concentrations, alipoic acid did not affect cell proliferation but at higher doses, it had an inhibitory effect on (3) H-thimidine uptake. It did enhance collagen production. This study demonstrated that proanthocyanidin did not affect cell proliferation but significantly increased collagen synthesis by cultured fibroblasts.
(1.) Thirunavukkarasu V, N. AT, A. Cv, Department of Biochemistry, faculty of science, Annamalai University, India, Exp. Diabesity res. 2004, Oct-Dec, 5(4): 237-44.
(2.) Dembure PP, JAR, Priest JH, Elias LJ, Metabolism 1987 Jul; 36(7): 687-91.
(3.) Fuchs J, Kern H, Free Raic. Biol. Med 1998. dec:25(9): 1006-12. Department of Dermatology, medical school, J. W. Goethe University, Frankfurt, Germany.
(4.) Heinrich U., tronler H, stahl W, Bejot M, Maurette JM,. Institute of Experimental Dermatology, University of Witten/Herdecke, Witten, Germany.
(5.) Shi J, Yu J, pohorly JE, kakuda Y. J. med. Food, 2003, Winter; 6(4); 291-9. Food research center, agriculture and Agri-Food Canada, Guelph, Canada.
(6.) Han B, Nimni ME, Connect. Tissue Res. 2005; 46 (4-5): 251-7, Department of Surgery, Keck School of Medicine and Biochemical Engineering, University of Southern California, Los Angeles, CA.
NAVIN GERLA IS VICE PRESIDENT OF RESEARCH AND DEVELOPMENT FOR SPADERMACEUTICALS, MANTINSVILLE, NJ. HE HAS MORE THAN 30 YEARS OF EXPERIENCE IN THE PERSONAL CARE INDUSTRY ADO WAS PREVIOUSLY WITH PFIZER, WARNER-LAMBERT, SCHICK, BRISTOL-MYERS AND, MOST RECENTLY, LEDERMA CONSUMER PRODUCTS LABORATORIES. He HAS EARNED OVER 15 U,S, PATENTS, HAS BEEN PUBLISHED IN COSMETIC TRADE MAGAZINES AND HAS BEEN BOTH A SPEAKER AND MODERATOR AT COSMETIC INDUSTRY EVENTS. E-MAIL: TOKUHO02@VERIZON.NET.