Psoriasis is an immune-mediated, chronic, inflammatory disease affecting about 80 million people worldwide. It is not life threatening, but those with psoriasis may have a higher incidence of diabetes, psoriatic arthritis, heart disease, and depression. The role of nutrition in the treatment of psoriasis has been well studied, and even more so given the increasing interest in those co-morbid conditions that are associated with psoriasis which also respond to nutritional interventions.
Recent progress in the understanding of psoriasis has shown that the regulation of immune products called cytokines plays an important role in its pathogenesis. Psoriasis is associated with an increase of inflammatory cytokines, which can be manipulated by simple dietary changes. Alcohol consumption, for example, may predispose individuals, especially men with a family history of psoriasis, to developing psoriasis. Whilst the exact molecular mechanisms by which alcohol triggers or exacerbates psoriasis are yet to be fully elucidated, it is believed that alcohol consumption may induce immune dysfunction and enhance the production of inflammatory cytokines as well as products that trigger the epidermal hyper-proliferation (exaggerated growth) associated with psoriasis plaques.1 Prolonged alcohol consumption also results in a myriad of nutritional deficiencies, including vitamin and trace element deficiencies such as zinc and selenium that may contribute to poor wound healing, further exacerbating symptoms. Avoiding alcohol is certainly advisable.
Interestingly, many patients with psoriasis also show elevated sensitivity to gluten. Although antigliadin antibodies are markers of coeliac disease, elevated levels of these antibodies are also seen in many other autoimmune disorders, including psoriasis.2 In fact, whilst not all individuals with psoriasis may benefit from eliminating gluten from their diet, many psoriasis patients (without associated arthritis) with a ‘silent’ (undiagnosed) coeliac disease can recover from their psoriasis when the coeliac disease is diagnosed and treated with a gluten-free diet.3
Many regulatory molecules, including inflammatory cytokines, are directly derived from the omega-6 fatty acid arachidonic acid. Accumulation of arachidonic acid, either by high consumption of oils and grains rich in its precursor linolenic acid, or directly through the consumption of products from animals that have been fed on grains rich in linolenic acid, can upset the balance of the omega-6/omega-3 ratio. As the precursor to inflammatory products and known to influence the production of inflammatory cytokines, arachidonic acid may be a key player in aggravating symptoms of psoriasis.4
However, the omega-6 pathway may also give rise to anti-inflammatory products although this is dependent on the amount of omega-3 in the diet. The two families share and compete for the enzymes needed for their conversions; increasing the intake of one family can impact on the conversion pathways of the other by ‘hogging’ the pool of available enzymes. We usually consume more omega-6 than omega-3, which allows the accumulation of arachidonic acid, hence we frequently consider omega-6 to be ‘bad’. However, by increasing omega-3 it is possible to shuttle the omega-6 down an anti-inflammatory route because the enzyme delta-5 desaturase involved in the production of arachidonic acid actually favours converting the omega-3 family over the omega-6 family. Combining the specific fatty acids GLA (an omega-6 found in high amounts in cold pressed organic evening primrose oil) with EPA (the omega-3 found in fish oil) offers the unique benefits of increasing the production of anti-inflammatory bi-products and reducing inflammatory cytokines, whilst indirectly inhibiting the production of arachidonic acid bi-products. Furthermore, switching to organic meat and organic dairy products can reduce the amount of arachidonic acid directly consumed, whilst increasing fish consumption can increase omega-3. Supplementation with high doses of EPA and GLA can further contribute to the regulation of inflammation and psoriasis symptoms.4
Several other supplements have proved to be of value in treating psoriasis, of which vitamin B, vitamin D and selenium are probably the most widely documented. High blood homocysteine and low vitamin B12 levels are positively associated with cardiovascular disease, but are also significantly correlated to psoriasis severity and it is generally accepted that individuals suffering from psoriasis are at a higher risk of developing cardiovascular health problems. Nutrients that reduce homocysteine are B12, B9 (folic acid), B2 (riboflavin) and B6 and they act through various chemical pathways to break down homocysteine in the blood, thereby reducing the risk of heart attack. However, not all nutrients need to be taken orally. For example, the active form of vitamin D, 1,25-dihydroxyvitamin D(3), exhibits anti-proliferative and immuno-regulatory effects via the vitamin D receptor, and can be taken both as a supplement and as a skin cream, having been successfully used in the topical treatment of psoriasis.
Psoriatic patients have been found to have pro-/antioxidant deficiencies deficienciesnd clinical trials with vitamin supplementation have also been performed with some degree of success. For example, carotenoids are vitamin A pro-vitamins with anti-oxidant properties that are present in human tissues, including skin; patients with psoriasis appear to have lower skin carotenoid counts than patients without psoriasis.5 As such, the efficacy of high-dose vitamin A, β-carotene, and vitamin A derivatives (retinoids) in treating mild-to-moderate psoriasis has been specifically attributed to their antioxidant action.
Individuals with a high daily intake (about 400 g) of fruits and vegetables will usually have higher antioxidant levels and higher levels of vitamin and trace elements than individuals consuming low amounts (< 100 g/day) of fruits and vegetables. Given that many water-soluble vitamins and minerals present in such foods play an active role in the initiation and progression of psoriasis symptoms, eating the recommended 5-a-day servings of fruit and vegetables is an important element of any healthy eating plan. Supplementing with a good quality vitamin and mineral supplement may further help to achieve levels needed as an adjunctive treatment in the management of psoriasis.
Avoiding ‘inflammatory’ foods such as alcohol, gluten (in some cases) and long-chain omega-6 (arachidonic acid) and increasing anti-inflammatory foods such as omega-3 EPA and omega-6 GLA, as well as ensuring optimal intake of vitamins and minerals, may certainly be of benefit when attempting to manage psoriasis symptoms.
- Kazakevich N, Moody MN, Landau JM, Goldberg LH. 2011 Alcohol and skin disorders: with a focus on psoriasis. Skin Therapy Lett. 2011 16:5-6.
- Nagui N, El Nabarawy E, Mahgoub D, Mashaly HM, Saad NE, El-Deeb DF. 2011 Estimation of (IgA) anti-gliadin, anti-endomysium and tissue transglutaminase in the serum of patients with psoriasis. Clin Exp Dermatol. 36:302-4.
- Michae¨lsson G, Gerde´n B, Hagforsen E, Nilsson B, Pihl-Lundin I, Kraaz W, et al. 2000 Psoriasis patients with antibodies to gliadin can be improved by a gluten-free diet. Br J Dermatol. 142:44-51.
- McCusker MM, Grant-Kels JM. 2010 Healing fats of the skin: the structural and immunologic roles of the omega-6 and omega-3 fatty acids. Clin Dermatol. 28:440-51.
- Lima XT, Kimball AB. 2011 Skin carotenoid levels in adult patients with psoriasis. J Eur Acad Dermatol Venereol. 25:945-9