**7. Vitamin D**

360 Psoriasis

is a need for prospective studies in order to determine the incidence of celiac disease and the real percentage of increased levels of antigliadin, antiendomysial and anti-tissue

A gluten-free diet can improve skin lesions even in patients without celiac disease but with the antigliadin antibodies IgA and IgG, which are important to the diagnosis of celiac disease (Michaelsson et al., 2003). Likewise, studies indicate that a gluten-free diet leads to an improvement in rheumatoid arthritis, which is another chronic inflammatory disease (Hafstrom et al., 2001). Data remains scarce in regards to the mechanisms involved in the association between celiac disease, psoriasis and a gluten-free diet in skin lesions. A number of hypotheses have been raised, such as an alteration in intestinal permeability, immune

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

Selenium is an essential trace element with immune-modulating and anti-proliferative properties, with an influence over the immune response whether through a change in the expression of cytokines and respective receptors or by making immune cells more resistant to oxidative stress (Celerier et al., 1995; Roy et al., 1992; Spallholtz et al., 1990). Moreover, data indicates that patients with inflammatory skin diseases, skin cancer, malignant melanoma and cutaneous T-cell lymphoma have low concentrations of selenium (Clark et

The low concentration of selenium found in patients with psoriasis may be a risk factor for the development of the disease. However, there are few studies on the role of this element in the pathogenesis (Hinks et al., 1987; Fairris et al., 1989; Michaelsson et al., 1989; Harvima et

al., 1984; Deffuant et al., 1984; Hinks et al., 1987; Michaelsson & Edqvist, 1984).

transglutaminase antibodies in patients with psoriasis (Ricketts et al., 2010).

mechanisms and vitamin D deficiency (Abenavoli et al., 2006).

**5. Oxidative stress and antioxidants** 

(Wolters, 2005).

**6. Selenium** 

Vitamin D is a pro-hormone that can be produced from 7-dehydrocholesterol through the exposure of skin to ultraviolet B rays of the sun. Besides its importance in the homeostasis of calcium and bone metabolism, calcitriol (the active form of vitamin D) has effects on more than 30 types of tissue, including skin (Wolters, 2005). Vitamin D plays an important role in reducing the risk of a number of chronic diseases, such as auto-immune diseases, infectious diseases, cardiovascular diseases and some forms of cancer (breast, colon-rectal and prostate cancer) (Fu &Vender, 2011).

Vitamin D plays an essential role in cell proliferation, differentiation, apoptosis and angiogenesis.Vitamin D also has beneficial effects on inflammatory diseases medicated by Th1 lymphocytes, such as diabetes, psoriasis, Crohn's disease and multiple sclerosis (Cantorna et al., 2004; Holick, 2007; Ikeda et al., 2010). Vitamin D has proven to be highly effective in the treatment of psoriasis, as patients having received vitamin D for the treatment of osteoporosis exhibited an improvement in psoriasis (Abramovits, 2009; Smith et al., 2009; Van De Kerkhof, 2005). Due to the function of calcitriol and its analogs in psoriasis, oral supplementation with vitamin D should be considered in patients who do not make use of topical treatment with this vitamin, as vitamin D deficiency is frequent in these individuals (Holick, 2003; Wolters, 2005).
