The Use of Probiotics in the Primary Prevention of Atopic Dermatitis: A Systemic Review of the Literature in Light of the Hygiene Hypothesis

Abstract

Atopic dermatitis (eczema) is a type 1 hypersensitivity reaction that is common in infants and young children, with incidence increasing in the Industrialised world. Based on epidemiological evidence, the hygiene hypothesis proposes that reduced exposure to infective organisms is associated with immune dysfunction (Seroni et al., 2010). Caesarean sections, lack of breast feeding, lack of exposure to micro-organisms and parasites in early life, widespread use of antibiotics and a more hygienic or clean environment is closely associated with the development of atopic dermatitis. This is explained by type 2 helper T-lymphocyte (Th2) cell dominance and a reduction in T-regulatory (Treg) cell function due to lack of stimulation via infectious organisms (Boon et al., 2006; Seroni et al., 2010) (Fig. 1). Furthermore, altered gut microbiota and dysbiosis due to similar risk factors has been implicated in the development of atopic dermatitis (Kranich et al, 2011). There has been recent interest in the use of probiotics in the prevention of atopic dermatitis. The terms atopic dermatitis and atopy are incorrectly used interchangeable in much of the literature, and this study will follow this protocol.