INTRODUCTION
In 1945, colloidal oatmeal compounds became available for the treatment of inflammatory skin conditions.1 In 1989, the Food and Drug Administration (FDA) recognized colloidal oatmeal as a safe and effective Category I ingredient, and it approved colloidal oatmeal as a skin protectant in 2003. Today, colloidal oatmeal suspensions are available in bath soaps, shampoos, shaving gels, and moisturizing creams.1 Moreover, a wide range of studies have been conducted that evaluate the efficacy and safety of colloidal oatmeal as adjunct treatment in the management of atopic dermatitis (AD), and these studies have found that moisturizers and/or cleansers containing colloidal oatmeal significantly improved many of the clinical outcomes associated with AD.2
Oats (Avena sativa) contain of a wide array of phytochemicals that include carbohydrates, proteins, lipids, flavonoids, avenanthramides, tocols, alkaloids, saponins, and sterols.3 The diverse chemical polymorphism of oats translates into a myriad of clinical utilities for AD and eczema. The high concentration in starches and beta-glucan in oats provide protective and water-holding functions.1 The saponins in oats are largely responsible for its cleansing activity.1 The antioxidant and anti-inflammatory effect of colloidal oatmeal is due in particular to the presence of avenanthramides, vitamin E, ferulic acid and other antioxidants.4,5 (Figure 1)
Avenanthramides are the principle polyphenolic antioxidants in oats.4 Although avenanthramides represent only a small constituent of oats, they can have significant effects on the inflammatory processes typical of AD. Sur and colleagues found that avenanthramides at concentrations as low as 1 parts per billion diminished phosphorylation of the p65 subunit of nuclear factor kappa B (NF-kappaB).6 Further, cells treated with avenanthramides showed a significant inhibition of tumor necrosis factor-alpha (TNF-alpha) and reduction of interleukin-8 (IL-8) release.6 Moreover, topical application of 1-3 ppm avenanthramides has allayed inflammation in murine models of contact hypersensitivity and neurogenic inflammation and reduced pruritogen-induced scratching in a murine itch model. Sur and colleagues concluded that the avenanthramides found in oats proved to be potent anti-inflammatory agents.
Chen and colleagues assessed the pharmacokinetics and antioxidant action of avenanthramide A, B, and C in healthy older adults in a randomized, placebo-controlled, 3-way crossover trial.7 Six subjects consumed 360 milliliters of skim milk alone (placebo) or containing 0.5 or 1 grams of an avenanthramide-enriched mixture extracted from oats. Plasma samples were collected over a 10-hour period, and the respective concentrations of avenanthramide A, avenanthramide B, and avenanthramide C in the avenanthramide-enriched mixture group were 154, 109, and 111 micromoles per gram. After consumption of 1 gram of avenanthramide-enriched mixture, plasma glutathione was elevated by 21% at 15 min (P < or = 0.005) and by 14% at 10 hours (P < or = 0.05). Thus, the investigators determined that oat avenanthramides are bioavailable and increase the glutathione antioxidant levels of healthy older adults.
