**5. Oxidative stress and antioxidants**

The skin is constantly exposed to oxidants, which leads to the formation of harmful reactive oxygen species (Briganti & Picardo, 2003). Oxidative stress and the increased formation of free radicals have been related to skin inflammation and are reported to be among the most important factors in the pathogenesis of psoriasis (Kiymat et al., 2003; Rocha et al., 2004; Relhan et al., 2002; Wolters, 2005). Studies demonstrate that individuals with psoriasis have high concentrations of malondialdehyde, OuvirLer foneticamentea marker of lipid peroxidation, and is compromised antioxidant status, with reduced levels of -carotene, tocopherol and selenium (Azzini et al., 1995; Briganti & Picardo, 2003; Serwin et al., 2003).

High alcohol intake (stemming from the psychosocial impact of the disease) and either active or passive smoking are among some of the factors that can increase oxidative stress and reduce levels of natural antioxidants in individuals with a history of the disease for more than three years (Lecomte et al., 1994; Mckenzie, 2000; Monk & Neil, 1986; Naldi et al., 1992). The consumption of fruit and vegetables may be beneficial to such individuals due to the high antioxidant content, such as karotenoids, flavonoids and vitamin C, as an adequate antioxidant status is considered useful to the prevention of imbalance between oxidative stress and antioxidant defense (Naldi et al., 1996; Wolters, 2005). However, few studies have investigated the effects of antioxidant supplementation on the symptoms of psoriasis (Wolters, 2005).
