**3. Polyunsaturated fatty acids**

Lipids are macronutrients that perform energy, structural and hormonal functions in organisms. Fatty acids are monocarboxylic acids with a hydrocarbon chain of variable size and double bonds between carbon atoms. These substances are classified as monounsaturated and polyunsaturated, depending on the number of double bonds they contain. Fatty acids are integral compounds of nearly all lipids. Two series of PUFAs are differentiated, depending on the location of the first double carbon bond at the methyl radical. Linoleic acid, which is an essential fatty acid, belongs to the omega 6 family and is found in a large quantity of oleaginous seeds; this acid can be converted into AA, which is prinicipally derived from meat and egg sources (Dutra-de-Oliveira, 2000). Eicosapentaenoic acid (EPA) and docosahexaenoic acid are the most abundant omega 3 fatty acids in food and are found mainly in cold-water fish, such as mackerel, sardine, salmon, herring, etc. (Wolters, 2005).

Besides their function in the phospholipid membrane, PUFAs are needed for the formation of eicosanoids, which are metabolic regulators (Jones & Papamandjaris, 2001). AA is a precursor of prostaglandins, leukotrienes and other compounds that have important functions in inflammation and the regulation of immunity, whereas EPA derivatives exhibit anti-inflammatory properties (Calder, 2001). High concentrations of AA and its pro-

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.

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

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

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.,

Lipids are macronutrients that perform energy, structural and hormonal functions in organisms. Fatty acids are monocarboxylic acids with a hydrocarbon chain of variable size and double bonds between carbon atoms. These substances are classified as monounsaturated and polyunsaturated, depending on the number of double bonds they contain. Fatty acids are integral compounds of nearly all lipids. Two series of PUFAs are differentiated, depending on the location of the first double carbon bond at the methyl radical. Linoleic acid, which is an essential fatty acid, belongs to the omega 6 family and is found in a large quantity of oleaginous seeds; this acid can be converted into AA, which is prinicipally derived from meat and egg sources (Dutra-de-Oliveira, 2000). Eicosapentaenoic acid (EPA) and docosahexaenoic acid are the most abundant omega 3 fatty acids in food and are found mainly in cold-water fish, such as mackerel, sardine, salmon, herring, etc.

Besides their function in the phospholipid membrane, PUFAs are needed for the formation of eicosanoids, which are metabolic regulators (Jones & Papamandjaris, 2001). AA is a precursor of prostaglandins, leukotrienes and other compounds that have important functions in inflammation and the regulation of immunity, whereas EPA derivatives exhibit anti-inflammatory properties (Calder, 2001). High concentrations of AA and its pro-

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

of the disease (Rucevic et al., 2003; Wolters, 2005)

the reintroduction of a normal diet (Ricketts et al., 2010).

**3. Polyunsaturated fatty acids** 

1999).

(Wolters, 2005).

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

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 al., 2010).

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).
