Psoriasis: Nutritional Considerations

Dietary strategies are aimed at eliminating inciting factors, reducing inflammation, and limiting calories.

Fasting, low-calorie diets, and vegetarian diets have all demonstrated effectiveness in reducing psoriasis.⁴ Part of the effectiveness is likely explained by weight loss. Obesity is significantly more common in patients with psoriasis than in control subjects.⁵ Recent evidence indicates that the odds ratio for psoriasis is increased to 1.6 in those who are overweight (body mass index of 26-29) and to 1.9 in persons with a body mass index (BMI) greater than 29.⁶

These dietary adjustments may have other consequences of benefit in psoriasis: lower production of proinflammatory leukotrienes (eg, LTB4) as a result of decreased arachidonic acid intake; declines in oxidative stress and inflammation;⁷ and reduced levels of insulin-like growth factor I (IGF-1).⁸ A vegetarian regimen may help to counteract the hyperlipidemia that is frequently associated with retinoid treatment.⁴

Anti-gliadin antibodies are a frequent finding in patients with psoriasis,⁹ and the psoriasis area and severity index (PASI) improves significantly in these patients on gluten-free diets.¹⁰ Similarly, in patients with celiac disease, a gluten-free diet may offer relief of psoriatic symptoms.⁴

Essential fatty acids. Patients with psoriasis may demonstrate linoleic acid deficiency and elevated skin levels of proinflammatory arachidonic acid,⁴ an omega-6 fatty acid found in meat, eggs, and milk. Higher intakes of linoleic acid (an omega-6 fatty acid) stem the excess production of leukotriene B₄ (LTB4), and are important for suppression of prostaglandin E2, an eicosanoid important for inhibition of the type 1 helper T cells (Th1) involved in psoriasis.¹¹ Intake of omega-3 fatty acids may also provide similar benefits with regard to these pro-inflammatory metabolites. Although smaller clinical trials of a combination of omega-6 and omega-3 fatty acids found no significant improvement in the severity of psoriasis,¹² others have found that omega-3 fatty acids improve the effectiveness of standard treatments; reduce the hyperlipidemia caused by etretinate therapy; prolong the beneficial effects of phototherapy; and reducing the nephrotoxicity of cyclosporin.¹³ Additional clinical trials are required before either omega-6 or omega-3 fatty acid supplements are used for the treatment of psoriasis, and moderation is advised regarding a substantial increase in either supplement, due to the risk for weight gain and the potential for polyunsaturated fats to increase oxidative stress.¹⁴

Alcohol avoidance. Excess alcohol intake is an important risk factor for psoriasis,¹⁵ possibly because alcohol can increase histamine production in psoriatic lesions⁴ and enhance proliferation of epidermal cells. In alcohol abusers, the disease often remits with abstinence and recurs upon resumed alcohol use.¹⁶ Even in light to moderate alcohol users, alcohol consumption is correlated with disease severity.¹⁷

Orders

See Basic Diet Orders.

Gluten-free diet in patients with anti-gliadin antibodies.

Smoking cessation.

Alcohol restriction, as appropriate.

Consider dermatologist referral as an outpatient.

What to Tell the Family

The family can play an important role in improving psoriasis symptoms. Family members can encourage the patient to use medications as directed. When a therapeutic diet is prescribed, family members can help by adopting a similar diet. Doing so facilitates adherence and may also reduce the family's health risks.