Dry skin is a common complaint by men and women alike and its incidence and severity increase with age. This condition is the result of an impaired barrier function, increased transepidermal water loss (TEWL) and a significantly lower level of ceramides in the horny layer that causes the skin to lose an excessive amount of water. This inability to retain moisture causes the skin to look dull and flaky, feel rough and lose elasticity. Dry skin can be due to genetic and metabolic factors, poor diet and certain conditions such as dermatitis, eczema or seborrhoea; however, in many cases, this type of skin is the result of chronic irritation by environmental and lifestyle factors. The conventional treatment of dry skin is to apply moisturizer or skin cream. These products work primarily by blocking the surface of the skin to increase the water content in the stratum corneum (SC), thus producing a state of hydration and imparting a temporary barrier to damaged SC.
Gamma-linolenic acid (GLA) has been suspected to be a conditionally essential component for optimal structure and function of the skin. That is, under certain conditions its requirement may exceed the individual’s capacity to synthesize this fatty acid and therefore has to be supplied pre-formed. GLA has been found in some vegetable oils such as evening primrose (EPO) and borage oil. These oils have been reported to have a skin barrier repairing effect, to normalize excessive transepidermal water loss, and to improve skin smoothness parameters after topical administration to healthy and irritated skin.
A recently published open-labelled study with elderly people using borage oil and a randomized, double-blind, placebo-controlled study with healthy adults using EPO4 not only confirmed these findings after systemic application, but also showed that oral supplementation could improve various biophysical skin parameters that are indicators of age-related structural and functional changes in healthy skin tissues. In view of the growing interest of the cosmetics industry in nutricosmetics and the widespread occurrence of stressed and dry skin, the present study was designed to test whether systemic EPO could be reproduced in a human model of irritated skin.