Phytonutrients protect the skin against harmful exogenous and endogenous agents and can help in remediation of skin disorders, so it’s no surprise that these materials are a driving force of innovation in skin research. In contrast, there are many synthetic ingredients used in cosmeceuticals today which does not provide nutrition to the skin.
Our slogan, at the International Cosmetics Science Center, is: “What you eat, is what you apply.”
Skin and Lipids
The skin is the largest organ of the human body. The approximate skin surface area of an adult weighing 62kg is 1.8m2. Skin shields the body from a variety of strains such as heat, cold and light including ultraviolet (UV) and other types of harmful irradiation. Other stressing factors with which the skin must cope are dehydration, noxious substances, insect bites and infection. To survive these strains, the skin performs a variety of specialized functions and reactions, including melanin and sebum production, keratinization and sweat excretion. Natural lipids are beneficial for the physical and biochemical properties of the skin.
The physical benefits include occlusivity, which, in cosmetics and pharmaceutical practice, refers to the ability of a substance that interferes with the evaporation of water from the skin surface. Any increase in transepidermal water loss (TEWL) decreases the level of water retained in the epidermis. This is a significant problem for people with atopic eczema, chronic contact eczema and other dry skin conditions.
In designing cosmetics for the repair of damaged skin and for skin protection, it is therefore important to assess the impact on TEWL. In this context, it is important to notice that the term “moisturization” is often preferred because “occlusion” may imply retention of dirt. In cosmetics, natural lipids are used as occlusive agents, but promoted as moisturizers.
The biochemical benefits of natural lipids include the regulation of epidermal growth, reduction of skin inflammation and provision of a skin barrier function. The barrier properties of the skin and the skin’s ability to retard transepidermal water loss depend on the presence of epidermal lipids. The permeability barrier in human skin is mediated by three lipid families, ceramides, free fatty acids and cholesterol, which are all present in an approximately equimolar ratio. The epidermal lipids are formed de novo by keratinocytes, although some lipids or their precursors are supplied from the circulatory system. Variations in the composition and proportion of these lipid families can lead to deterioration, normalization or acceleration of barrier repair.
Lipids in Cosmetics
The cosmetic industry has developed products to treat skin disorders and retain the skin’s natural beauty. Long ago, natural fats were the dominant emollient material, but later these were replaced in many applications by mineral oils. However, because of growing environmental awareness, an increasing interest in environmentally-friendly products, such as naturally renewable vegetable lipids, are finding ever-increasing use in a wide range of cosmetic applications.
More systematic studies of a wide range of plant seeds and their oils have identified many interesting materials. Previously unknown oils with unusual properties and chemical structures were discovered. Most lipid-based products are nontoxic, non-hygroscopic and normally, non-reactive with active ingredients. Some oils are rich in essential fatty acids, whereas others contain natural antioxidants or sunscreens. Therefore, it is no surprise that such oils are receiving more attention as safe and environmentally-friendly ingredients for the cosmetic formulator.
Lipids play an important role in the formulation and performance of many cosmetic products, ie. emollients or emulsifiers in a variety of applications including lipsticks, creams, lotions, makeup bases, moisturizers, bath oils, pressed powders, fragrances and a variety of cleansers for hair, face and body.
Vegetable oils are primarily triglycerides (triacylglycerols), in which the predominant fatty acids are palmitic and stearic acids and their mono- and polyunsaturated forms such as palmitoleic, oleic, linoleic acids. However, many other fatty acids also occur, usually in smaller quantities. These fatty acids can be combined in endless variations, resulting in a wide range of chemical and physical properties. Oils from the same plant species can show variations in the ratio of the same key fatty acids; this may occur as a result of genetic differences and weather influences.
This article focuses on highly beneficial properties of oat lipids in designing cosmeceuticals through the application of phytoconstituents. During the past few years, oats and products that contain them have received considerable attention due to their demonstrated health promoting effects when used in foods. Less attention has been focused on effects and potential of oat-based ingredients when used in cosmetic products or medical devices. However, traditional applications have shown positive effects, and evidence exists, that oat products are anti-allergic, anti-inflammatory, anti-irritative and skin calming. A part of this has been verified in non-published product development studies, another part based on non-existence of observed negative effects. Few systematic studies on the effects of oat oil as such on skin health have been published. On the contrary, a great number of scientific studies exist on skin health related effects of minor components found in oat oil.
The chemical composition of oat oil is favorable for these purposes. The share of polyunsaturated fatty acids is ca. 40% of total fatty acids indicating an oil of good nutritional quality, but also sensitivity to oxidation unless protected. Characteristic for the composition is a high proportion of polar lipids, which carry the main part of physiologically effective or protecting compounds. Total content of polar lipids is usually around 10% of oil. The content depends on oat variety and the method of extraction. A high yield of polar lipids is obtained when it is extracted with ethanol or other low-molecular alcohols or by supercritical extraction with blends of carbon dioxide and ethanol. Supercritical extraction with plain carbon dioxide results in an oil with low content of polar lipids.
The major components of polar lipids are phospholipids and glycolipids, which both have effective emulsifying properties. Several methods have been proposed for concentrating or separating these fractions, but availability of enriched products has been weak, and the present use is primarily based on non-fractionated oat oil. Even more sophisticated applications have been presented for glycolipids, which have the ability to form bilayer or multi-layered structures, a property which has been used for encapsulating medical products for targeted release at the desired site.
Major Minor Components
Ceramides are minor oat oil components, but they have similar or closely similar structure to human skin ceramides. They bind cells together and reduce moisture loss. Recent research has shown that they also have regulatory functions for cell differentiation, proliferation and programmed cells death, the latter includes suppression of tumor growth.
Antioxidants are another important group of minor components. The most effective of them are phenolic compounds including avenanthramides, caffeic and ferulic acid and their derivatives, and tocopherols. In addition to preserving the quality of the fatty product, they inactivate free radicals arising both from oxidation of lipids, ultraviolet light and from other radiation sources. For consumers, oat oil is an advantageous choice due to its emolliency and ability to reduce TEWL. The presence of polar lipids enables oat oil to easily penetrate the skin.
It is a real challenge for cosmetic chemists to learn about the diversity of complex lipids. A clear agenda for skin care formulation with natural ingredients is hindered by an extreme lack of formulation technology.
The future belongs to the products that are natural, safe, innovative, high performing and above all, elegant feeling. Aging consumers seek products that show measurable effects for minimal cost. New anti-aging ingredients continue to develop as the best hope for conserving youth. The newly-developed solutions that claim to protect from UV rays and pollutants are always in demand.
Products made with natural ingredients have always been and always will be in demand. Multifunctional properties provide significant value in beauty care, as consumer is getting more for the money. These products are mainly successful due to their advertising effect, providing strong and clear message which is attractive, persuasive and memorable.
- Shukla, Vijai K.S.: Designing Natural Cosmetics through the Dynamics of Naturally Derived Lipids, INFORM, Vol. 15 (4) (April 2004).
- Shukla, Vijai K.S.: The Challenges of Skin Care, INFORM, Vol. 15 (5) (May 2004).
- Shukla, Vijai K.S.: Organic Health Food for Rejuvenated Bio Skincare Formulations Employing the Power of Chemopreventers, Natural Ingredients: Cosmetic Science Technology, 2008.
- Shukla, Vijai K.S.: Innovative Organic Lipids in Filtering the Chemistry in Cosmeceuticals, Cosmetic Science Technology, 2009.
- Shukla, Vijai K.S., Nielsen, Søren: Studies in the Evaluation of Unconventional Oils from Burkina Faso, Part One: Rich in Oleic Acid (C18:1 n-9), Cosmetic Science Technology 2014.
- Shukla, Vijai K.S., Nielsen, Søren: Studies in the Evaluation of Unconventional Oils from Burkina Faso, Rich in Linoleic acid (C18:2 n-6) or other unusual fatty acids, Part 2: Cosmetic Applications 2015.
- Peterson, David M., Oat Antioxidants, Journal of Cereal Science 33(2):115-129, 2001.
Prof. Dr. Vijai K.S. Shukla is the founder and CEO of International Cosmetics Science Centre A/S, Denmark. He is world renowned professor and has received many prestigious US awards. He is a central figure in the study of essential fatty acids. He has authored more than 100 peer-reviewed papers, reviews and book chapters and 15 books. He was the associate editor for the peer-reviewed journal INFORM from 1989–97 and remains associate editor of the Journal of the American Oil Chemists Society and of Lipid Technology. In 1996 he received the American Oil Chemists’ Society (AOCS) Herbert Dutton Award for “significant contributions to analytical methodologies” and was given the prestigious Stephen S. Chang Award in 2002 for “decisive accomplishments in research for the improvement or development of products related to lipids.”
Prof. Yrjö Mälkki has been the director of Food Research Laboratory of Technical Research Centre in Finland and is an associate of the International Cosmetics Science Centre A/S, Denmark.
More info: International Cosmetics Science Center A/S, Denmark, www.icsc.dk