**1. Introduction**

356 Psoriasis

Zeinn, N.N. & Etanercept Study Group. (2005). Etanercept as an adjuvant to interferon and

Vol.42, No.3, pp.315-322.

ribavirin in treatment-naive patients with chronic hepatitis C virus infection: a phase 2 randomized, double-blind, placebo-controlled study. *Journal of Hepatology,* 

> Diet has been suggested to play a role in the etiology and pathogenesis of psoriasis (Araujo et al., 2009; Wolters, 2005). Periods of fasting, a hypocaloric and vegetarian diet have been associated with an improvement in symptoms due to changes in the metabolism of polyunsaturated fatty acids (PUFAs) and an influence on the profile of eicosanoids, leading to suppression of the inflammatory process (Lithell et al., 1983; Rucevic et al., 2003; Wolters, 2005). The consumption of alcoholic beverages is prevalent among patients with psoriasis and is the greatest cause of the high mortality rate among individuals with moderate to severe forms of the disease and should therefore be avoided (Chistophers, 2001; Poikolainen et al., 1990; Smith & Fenske, 2000; Wolters, 2005). According to several authors, calcitriol (the active form of vitamin D) and its analogs have anti-proliferation, pro-differentiation and immune-regulating properties that may inhibit the growth and maturation of keratinocytes, with oral supplementation often suggested for patients who do not topically use calcitriol (Andorini, 2002; Holick, 2003; Wolters, 2005).

> The skin acts as an interface between the body and surrounding environment, thus the skin is constantly exposed to both endogenous and exogenous pro-oxidants, leading to the generation of harmful oxidant species. Oxidative stress and the generation of excessive free radicals have been related to skin inflammation in psoriasis. Patients with this condition have reduced plasma levels of β-carotene and α-tocopherol as well as a decline in serum selenium and high concentrations of malondialdehyde, which is a marker of lipid peroxidation in the plasma and red blood cells (Briganti & Picardo, 2003; Azzini et al., 1995; Serwin et al., 2003).

> Data from literature indicates that the topical application or oral administration of antioxidants is suggested as preventive therapy for the natural aging of the skin and cancer caused by ultraviolet rays (Briganti & Picardo, 2003). With regard to lipids, studies have demonstrated the anti-inflammatory effect of fish oil in individuals with psoriasis, as diets rich in omega 3 modify the metabolism of PUFAs, thereby influencing the profile of eicosanoids, which leads to the suppression of the inflammatory process (Smith & Fenske, 2000). A number of authors report an association between latent sensitivity to gluten (preceliac disease state) and different skin diseases, including psoriasis, suggesting a gluten-free diet may provide beneficial effects (Duggan, 2004; Humbert et al., 2006; Leffler et al., 2003; Michaelsson et al., 2003; Nelson, 2002; Wolters, 2005).

Food, Nutrition and Diet Therapy in Psoriasis 359

inflammatory metabolites have been observed in psoriatic lesions as well as in other autoimmune and inflammatory disorders. Therefore, one treatment option for psoriasis may be the replacement of AA with an alternative fatty acid, especially EPA, which is metabolized

Fish oil (omega 3), has been observed to change the serum and lipid composition of epidermal and blood cell membranes, which rationalizes its use in the treatment of psoriasis. High levels of AA are found in psoriatic lesions and it is believed that its metabolite, leukotriene B4, may be the mediator of inflammation in psoriasis (Ricketts et al., 2010). Thus, when omega 3 fatty acids are metabolized by cyclooxygenase or lipoxygenase in place of AA in the cell membranes, these substances may assist in reducing inflammation (Ricketts et

Conflicting results are reported regarding the effect of the oral supplementation of omega 3 on this disease and there are no clear findings regarding the dose to be employed (Mayser et al., 2002; Wilkinson, 1990). In vitro studies report that the addition of fish oil to the diet of individuals with psoriasis leads to an increase in EPA in relation to AA in the plasma and platelets, with a significant reduction in the synthesis of leukotriene B4 (Ricketts et al., 2010) Initial studies involving different amounts of EPA ranging from 3.6 to 14 grams per day for periods of six weeks to six months report some clinical improvement with minimal side effects; however, lower doses for a shorter period of time are reported to offer no significant improvement (Maurice et al., 1987; Ziboh et al., 1986; Kragballe & Fogh, 1989; Kojima et al., 1989). The majority of studies report positive results; however, less effective results are reported in randomized, controlled trials (Wolters, 2005). Despite the inconsistent results, the consumption of fish rich in omega 3 is recommended. Moreover, parenteral infusions of omega 3 may be beneficial to patients hospitalized with acute psoriasis (Wolters, 2005).

Celiac disease is an enteropathy associated with different extra-intestinal manifestations, such as anemia, transaminase elevation, osteopenia, neurological conditions, emotional and psychiatric disorders, auto-immune disease and dermatological problems. This disease is characterized by an allergy to gluten (a protein found in wheat, oats, rye and barley), leading to malabsorption and atrophy of the intestinal villi, which improves with a gluten-

This gluten-sensitive enteropathy tends to bemildly symptomatic and even asymptomatic, which may explain the association between latent gluten sensitivity and psoriasis (Wolters, 2005). A number of studies report an association between celiac disease and psoriasis (Michaelsson et al., 2000; Woo et al., 2004). According to some authors, however, this association is controversial due to currently limited data (Addolorato et al., 2003; Collin & Reunal, 2003). Since both celiac disease and psoriasis are related to T helper 1 (Th1) cytokines, this association could be caused by the activation of Th1 by the interleukins IL1 and IL8, stemming from the rapid division of keratinocytes (Ojetti et al.,

There is no consensus among current literature regarding the high prevalence of patients with psoriasis and antibodies associated to celiac disease (Ricketts et al., 2010). Thus, there

through the same enzymatic pathways as AA (Mayser et al., 2002; Wolters, 2005).

al., 2010).

**4. Gluten** 

2003).

free diet (Abenavoli et al., 2006).

The aforementioned data underscore the importance of studies on psoriasis, especially with regard to the influence of nutrition on the etiopathogenesis and treatment of this condition.
