n-3 Polysaturated Fatty Acids-rich Diet in Psoriasis
Condition: Plaque-type Psoriasis; Obesity (Body Mass Index >30 kg/m2)
MeSH terms: Psoriasis
Study type: Interventional
Phase: Phase 4

Summary: 
      Low-grade systemic inflammation associated with obesity may worsen the clinical course of
      psoriasis. Both a low-calorie diet and nutritional supplementation have been shown to have an
      impact on the clinical course of psoriasis, including an anti-inflammatory effect of n-3
      polyunsaturated fatty acids (PUFAs). This study aimed to assess the effectiveness of an
      energy-restricted diet, enriched in n-3 PUFAs and poor in n-6 PUFAs, on metabolic markers and
      clinical outcome of obese patients with psoriasis.

      Methods: Forty-four obese patients with mild-to-severe plaque-type psoriasis treated with
      immuno-suppressive drugs were randomized to assume either their usual diet or an
      energy-restricted diet (20 kcal/kg/ideal body weight/day) enriched of n-3 PUFAs (average 2.6
      g/d). All patients continued their immuno-modulating therapy throughout the study. End-point
      measures included anthropometric, biochemical and clinical parameters at baseline, 3 and 6
      months.
    

Detailed description: 
      Psoriasis is one of the most common chronic inflammatory skin disorders, affecting about 2%
      of the general population. It is considered to be a T-cell-mediated inflammatory skin disease
      which is characterized by hyper-proliferation and poor differentiation of epidermal
      keratinocytes. Even if the susceptibility to psoriasis is inherited, the inflammatory
      reaction is modulated by diet, lifestyle and environmental factors such as infections and
      stress. Polyunsaturated fatty acids (PUFAs) are showing promise as safe adjunctive treatments
      for many skin disorders, including psoriasis.

      There are two main families of PUFAs: n-3 and n-6 PUFAs. Alpha-linolenic acid (ALA) is the
      only essential n-3 PUFA, while linoleic acid is the only essential n-6 PUFA. These fatty
      acids form the building blocks for downstream long-chain fatty acids: On the n-6 side,
      linoleic acid converts to gamma-linolenic acid (GLA) and dihomo-gamma-linolenic acid (DGLA),
      the latter of which may be converted to either pro-inflammatory arachidonic acid (AA) or
      anti-inflammatory prostaglandins, prostaglandin E1 (PGE1). AA (which can also be derived from
      the diet) is primarily a precursor to pro-inflammatory eicosanoids, prostaglandin E2 (PGE2),
      and leukotrienes and, to a much smaller extent, anti-inflammatory prostacyclin. On the n-3
      side, a small amount of ALA converts to eicosapentaenoic acid (EPA), and then to
      docosahexaenoic acid (DHA). EPA serves primarily as a precursor to anti-inflammatory
      prostaglandins, prostaglandin E3 (PGE3) and inhibits both the production of AA from DGLA and
      the production of PGE2 or thromboxane from AA. Skin cells produce eicosanoids in response to
      various stimuli contributing to inflammatory conditions.The active involvement of fatty acids
      in skin health and epidermal barrier function justifies the choice of systemic
      supplementation with n-3PUFA as an effective strategy for the improvement of inflammatory
      conditions. Epidemiological observations of a lower incidence of autoimmune and inflammatory
      disorders, including psoriasis, in a population of Greenland Eskimos compared with gender-
      and age-matched groups living in Denmark provided early suggestive evidence of the important
      role of n-3 PUFAs dietary intake on inflammation. An improvement in psoriasis has also been
      observed during daily dietary supplementation with fish oil containing n-3 PUFAs. As
      mentioned, AA is a pro-inflammatory fatty acid. As a result, a low dietary intake of AA,
      typical of low-protein and vegetarian diets, may produce a less anti-inflammatory effects.
      The Western diet is "deficient" in n-3 PUFAs, with an n-6/n-3 ratio of 15/1 to 16/1, as
      compared to the 1/1 ratio as found in wild animals and presumably human beings prior to the
      industrial revolution. Although the ability of a low-protein diet to improve symptoms in
      psoriasis patients has not been consistently supported a remarkable treatment efficacy was
      reported for a patient by Schamberg. In a case-control study, Naldi et al showed that an
      increased intake of fresh fruits and certain vegetables was linked to a decreased prevalence
      of psoriasis, although the mechanism was not clear.

      Calorie restriction and/or weight loss may also influence symptom severity in psoriasis. In
      obese patients with moderate-to-severe plaque psoriasis, weight loss was shown to improve the
      therapeutic response to cyclosporine. In mice, four weeks of calorie restriction (by 33% of
      energy intake) led to a decrease of 45% in the epidermal cell proliferation rate. Likewise,
      symptoms of inflammatory diseases such as rheumatoid arthritis have been shown to be improved
      through fasting or low-energy diets. Associations have also been recognized between psoriasis
      and an increased incidence of metabolic syndrome (visceral obesity, diabetes or insulin
      resistance, hypertension, and dyslipidemia). Although the link between psoriasis and
      individual components of metabolic syndrome is not completely elucidated, visceral fat, which
      releases pro-inflammatory cytokines, appears to play a role in both metabolic syndrome and
      psoriasis.

      Additional factors influencing the severity of psoriasis have been examined, such as alcohol
      consumption. Alcohol may enhance the production of inflammatory cytokines and cell cycle
      activators, which could lead to epidermal hyperproliferation. Although there is no generally
      recognized decisive cure for psoriasis, many treatments are commonly used to reduce the
      severity of symptoms and lessen their impact on the patient's quality of life. For
      moderate-to-severe psoriasis, phototherapy and topical and/or systemic therapies are the
      standard medical therapies. Examples include corticosteroids, emollients, tar, methotrexate,
      and cyclosporine. However, many of these treatments are associated with significant adverse
      effects. Some alternative systemic therapies include monoclonal antibodies, fumaric acid
      esters, vitamin D analogs, novel retinoids, macrolactams, and biologic immune modifiers such
      as anti-tumor necrosis factor (TNF) agents.

      The present study explores the effectiveness of an energy-restricted n-3 fatty acid-rich diet
      on the nutritional and clinical outcome of obese patients with mild-to-severe psoriasis.
    

Intervention name(s): Energy-restricted, n-3 polysaturated fatty acids-rich diet; Usual diet
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): The active diet aimed to reduce body weight, to enhance the total intake of n-3 PUFA and to decrease the total intake of n-6 PUFAs. The diet plan was designed to supply an energy intake of 20 kcal/kg/day to maintain an ideal body weight, and followed the guidelines of the American Heart Association (AHA) 'Step-One' Diet: Carbohydrates (mainly complex carbohydrates) and protein constituted of 50-60% and 10-20% of total calories, respectively, and total fat did not exceed 30% of calories. Food values for energy and nutrients were taken from the tables of the Italian National Institute of Nutrition, Souci's Food Composition and Nutrition Tables and the European Institute of Oncology. For long-term and practical daily eating habits, it was important to easily incorporate and consume a variety of selected foods.; The patients of this group were randomized to continue their usual diet
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: psoriasis; obesity