The authors describe peroxisome proliferator-activated receptor (PPAR) transcription factors as connectors between the enzymatic mechanisms of the epidermal barrier and the abnormal immune and inflammatory responses that characterize atopic dermatitis and psoriasis. Also described is a new connection between lipid metabolism and the epidermal barrier. A suggestion that emerges is that atopic dermatitis and psoriasis share at least 2 pathogenic mechanisms-namely, deficient expression of PPAR-#a and impaired production of interleukin-10 and interferon-γ-in spite of differences in causes and manifestations. A standardized olive oil formulation with powerful bactericidal and fungicidal effects also has the ability to increase serum levels of these 2 cytokines and regulate serum levels of high-density lipoprotein cholesterol in patients at high risk for inflammatory and cardiovascular disease, suggesting that these may be among the mechanisms responsible for the benefits observed following oral and/or topical administration in patients with atopic dermatitis or psoriasis.