**2. Influence of calorie intake, periods of fasting and vegetarian diet**

A number of studies report that symptoms of inflammatory disease, such as rheumatoid arthritis, can improve with a hypocaloric diet or during periods of fasting (Muller et al., 2001; Palmblad et al., 1991). Similarly, the prevalence and severity of psoriasis were shown to improve during periods of fasting and a hypocaloric diet,suggesting diet to be an important consideration for theprevention and treatment of the moderate non-pustular form of the disease (Rucevic et al., 2003; Wolters, 2005)

While various mechanisms have been discussed, the direct cause of these positive effects on the symptoms of psoriasis remains unknown (Wolters, 2005). The most important reason is likely a reduction in arachidonic acid (AA) intake, resulting in a lower production of inflammatory eicosanoids. During the fasting state, a reduction in the activation of TCD4 cells and an increase in the number and/or function of the anti-inflammatory cytokine interleukin 4 have been observed; Calorie restriction leads to a reduction in oxidative stress (Fraser et al., 1999; Wolters, 2005). However, the few studies that have addressed the effect of caloric restriction on psoriasis offer inconsistent data on the benefits of this conduct over a long period of time (Lithell et al., 1983; Rucevic et al., 2003). The results of evaluations carried out during World War I revealed that individuals with psoriasis experienced significant improvement during calorie restriction, with the recurrence of skin lesions after the reintroduction of a normal diet (Ricketts et al., 2010).

A vegetarian diet may be beneficial to all patients with psoriasis due to the reduction in AA intake and consequent reduction in the formation of inflammatory eicosanoids (Fraser et al., 1999).
