Anti-Inflammatory Activities of Colloidal Oatmeal (Avena sativa) Contribute to the Effectiveness of Oats in Treatment of Itch Associated With Dry, Irritated Skin

January 2015 | Volume 14 | Issue 1 | Original Article | 43 | Copyright © 2015

Kurt A. Reynertson PhD, Michelle Garay MS, Judith Nebus MBA, Suhyoun Chon PhD, Simarna Kaur PhD,
Khalid Mahmood PhD, Menas Kizoulis BA, Michael D. Southall PhD

Johnson and Johnson Consumer Products Company, Inc., Skillman, NJ

Abstract

BACKGROUND: Oat (Avena sativa) in colloidal form is a centuries-old topical treatment for a variety of skin conditions, including skin rashes, erythema, burns, itch, and eczema; however, few studies have investigated the exact mechanism of action for the anti-inflammatory activity of colloidal oatmeal.
METHODS: Four extracts of colloidal oatmeal were made with various solvents and tested in anti-inflammatory and antioxidant assays. In addition, an investigator blind study was performed with twenty-nine healthy female subjects who exhibited bilateral mild to moderate itch with moderate to severe dry skin on their lower legs. Subjects were treated with a colloidal oatmeal skin protectant lotion.
RESULTS: Extracts of colloidal oatmeal diminished pro-inflammatory cytokines in vitro and the colloidal oat skin protectant lotion showed significant clinical improvements in skin dryness, scaling, roughness, and itch intensity.
CONCLUSIONS: These results demonstrate that colloidal oat extracts exhibit direct anti-oxidant and anti-inflammatory activities, which may provide the mechanisms for observed dermatological benefits while using the colloidal oatmeal skin protectant lotion.

J Drugs Dermatol. 2015;14(1):43-48.

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INTRODUCTION

Oats (Avena sativa) have been cultivated since the Bronze Age, and have been used in traditional medicine for centuries. As a topical treatment, colloidal oatmeal has emollient and anti-inflammatory properties, and is commonly used for skin rashes, erythema, burns, itch, and eczema.1-3 Historically, investigations into the phytochemical constituents of oat have focused primarily on their value as a food. For example, β-glucan is the “soluble fiber” that makes oats a heart-healthy food. β-glucans have also been used as scaffolds for the growth of bioartificial skin, and are known to assist in wound healing, response to injury and infection, and have a great water retention capacity.4

Colloidal oatmeal is the finely ground whole oat kernel or groat, and is an active natural ingredient covered by the FDA OTC Skin Protectant monograph in the US. The oat grain is ground and processed until no more than 3% of the total particles exceed 150 μm and no more than 20% exceeds 75 μm.5 The composition of colloidal oatmeal largely consists of starch (65-85%), protein (15-20%), lipids (3-11%), fiber (5%) and β-glucans (5%).3,6

Oat lipids are primarily composed of triglycerides, along with polar lipids and unsaturated free fatty acids. Oat triglycerides are rich in omega-3 linoleic and omega-6 linolenic acids and essential fatty acids7 which are necessary for normal mammalian health and important for skin barrier function.8-10 In addition, oat lipids contain important mammalian cell membrane components, such as phospholipids, glycolipids, and sterols. Lipid oxidation protection is supplied by mixed tocopherols (vitamin E) and tocotrienols.

Colloidal oatmeal is also a rich source of phenolic antioxidants and saponins. Avenanthramides, nitrogen-containing phenolic compounds specific to oats, are potent antioxidants and anti-inflammatory agents that have been previously shown to inhibit NF-kB and IL-8 release in a dose dependent manner.3,11-13 Saponins are glycosylated metabolites which help to protect oat plants from disease,14 and which can also help create stable emulsions when colloidal oatmeal is used in a formulation.

Despite a rich history of traditional use, there remain some gaps in the understanding of the exact mechanisms that give colloidal oatmeal its clinical benefits; we conducted a series of in vitro experiments and a clinical study to help identify the mechanism of action for the clinical benefit of colloidal oatmeal. We made four extracts of colloidal oatmeal with organic and aqueous solvents to concentrate constituents based on compound polarity, and subjected them to antioxidant and anti-inflammatory assays. In addition, an investigator-blind clinical study was conducted to evaluate the efficacy of a colloidal oatmeal skin protectant lotion in alleviating extra dry, itchy skin.

Healthy female subjects with bilateral itch and moderate to severe dry skin on their lower legs were enrolled in a 2-week study. Subjects applied a set amount of the lotion to the lower leg

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