Novel Antibacterial and Emollient Effects of Coconut and Virgin Olive Oils in Adult Atopic Dermatitis

Vermén M. Verallo-Rowell; Kristine M. Dillague; Bertha S. Syah-Tjundawan


Dermatitis. 2008;19(6):308-315. 

In This Article

Abstract and Introduction

Background: Atopic dermatitis (AD) skin is dry and readily colonized by Staphylococcus aureus (SA). Coconut and olive oils are traditionally used to moisturize and treat skin infections.
Objective: To compare virgin coconut oil (VCO) and virgin olive oil (VOO) in moisturizing dryness and removing SA from colonized AD skin.
Methods: This was a double-blind controlled trial in two outpatient dermatology clinics with adult AD patients who were diagnosed by history, pattern, evolution, and skin lesions and who were randomized to apply VCO or VOO twice daily at two noninfected sites. SA cultures, photography, and objective-SCORAD severity index (O-SSI) scoring were done at baseline and after 4 weeks.
Results: Twenty-six subjects each received VCO or VOO. Of those on VCO, 20 were positive for SA colonies at baseline versus 12 on VOO. Post intervention, only 1 (5%) VCO subject remained positive versus 6 (50%) of those on VOO. Relative risk for VCO was 0.10, significantly superior to that for VOO (10:1, p = .0028; 95% CI, 0.01-0.73); thus, the number needed to treat was 2.2. For the O-SSI, the difference was not significant at baseline (p = .15) but was significantly different post treatment (p = .004); this was reduced for both oils (p < .005) but was greater with VCO.
Conclusion: VCO and monolaurin's O-SSI reduction and in vitro broad-spectrum activity against SA (given clinical validity here), fungi, and viruses may be useful in the proactive treatment of AD colonization.

Atopic Dermatitis (AD) is characterized by dry skin and the frequent isolation of Staphylococcus aureus (SA) from infected eczema and chronic lesions and as a colonizer of clinically uninfected atopic skin.[1] The prevalence of colonization in normal skin is about 5%; in lesional and nonlesional atopic skin of adults, children, and infants, it is 64 to 100%.[2] Thus, based on a recent systematic review of AD, it is felt that the use of a topical antibiotic for treating SA infection can be effective, but the development of resistance is a concern. Treatment of SA colonization is not as clear-cut. The review further states that antibiotics generally have a minimal therapeutic effect on dermatitis without signs of infection.[3]

A recent review on the mechanisms of disease in AD explored (1) the role of SA colonization and infection in helping generate the chronic inflammation characteristic of atopic skin and (2) the role of inflammation (from SA and from genetic and environmental causes) that leads to barrier dysfunction that culminates in dry skin. Rather than endorse the more common reactive management of AD, the review recommended early and proactive intervention with antiseptic lotions to reduce SA colonization.[4]

Few evidence-based data are accepted in modern therapeutics for the widespread traditional practice of using coconut oil (CO) on dry infected skin.[5] In a small trial of patients with xerosis, Agero and Verallo-Rowell found CO comparable to mineral oil in skin moisturization and the absence of irritant effects.[6] No trials have been reported on the topical use of CO specifically for AD, clinically infected or not.

In recent years, the term "virgin" has been used to indicate a health-related value in coconut and olive oils. The virgin status of olive oil is achieved by extracting the oil 24 to 48 hours after harvest and through Good Manufacturing Practice (GMP), including the avoidance of heat, light, and air during processing and storage. These precautions protect heat-sensitive phytochemicals and help prevent the hydrolysis of triglycerides into their component free fatty acids (FFAs), which leads to the rancid smell of spoilage and to skin irritation.[7] The amount of FFAs present is used to define the degree of virginity of the oil, as follows: ordinary, a maximum of 3.3%; fine virgin, a maximum of 1.5%; and virgin, less than 1%. "Extra-virgin olive oil" (EVOO) is a retailing name used to emphasize the fact that the oil is pressed cold immediately after harvest.[8]

Virgin coconut oil (VCO) is also processed on the day of harvest, under similar GMP guidelines.[9] Unlike virgin olive oil (VOO), which has 82% unsaturated fatty acids (FAs), VCO has only 8% unsaturated FAs. The other 92% of the FAs are saturated and chemically stable such that the standard of 0.5% FFA content in VCO is readily achieved as long as the moisture content is kept at the standard of 0.12% or less. Since the nutmeat is exposed to its water at tropical temperatures for 10 months, extra-virgin coconut oil (EVCO) is considered "cold pressed" when the nutmeat is pressed at a temperature that does not exceed 39ºC.[10] For the objectives of this study, these differences are minor; hence, the more common terms for these two virgin oils-VCO and VOO-are used in this article.

This 4-week randomized controlled blinded trial compared the effects of VCO and VOO on SA colonization of normal AD skin and on the extent and intensity of objective AD parameters, using the objective SCORing Atopic Dermatitis (SCORAD) severity index (O-SSI).