Published in JAMA Dermatology, researchers recently reviewed the associations between psoriasis and diet based on four popular dietary recommendations.
Psoriasis is a chronic, inflammatory disease resulting in scaling and irritation of the skin. This autoimmune condition impacts 3.2 % of the American population. Many patients who are diagnosed with psoriasis are also diagnosed with related diseases including psoriatic arthritis, gastrointestinal disease, and cardiometabolic disease among others. While many individuals with psoriasis report experiencing fewer symptoms as a result of changes in their diet, there is a lack of scientific proof of the positive effects of certain recommendations regarding psoriasis and diet.
The National Psoriasis Foundation (NPF) Medical Board recently conducted a systematic review to determine dietary recommendations for patients with psoriasis. Their results were published in JAMA Dermatology.
The researchers assessed 55 studies that met the following criteria:
1. Participants with psoriasis, psoriatic arthritis, or both
2. Studies assessed patterns of diet/nutrition or differences in diet/nutrition among participants
3. Outcomes must have included either the development of psoriasis or changes in severity of the condition
One caveat of the NPF’s research methods was that while 55 studies may seem more than sufficient to draw conclusions about the association between diet and psoriasis, there was insufficient data to make conclusions about pediatric psoriatic patients.
The researchers assessed the association between psoriasis and diet based on four dietary recommendations:
1. Gluten-free Diet
2. Reduction in dietary weight
3. Use of dietary supplements
4. Specific diets, foods, or diet patterns
Their findings are described below.
There has been a growing popularity with gluten-free diets to lessen the severity of symptoms experienced by psoriatic patients. One of the reasons for this is that psoriatic patients have a 100 times higher probability of contracting other autoimmune diseases, specifically celiac disease.
Celiac disease is characterized by the inability to process gluten. Whether you are aware of it or not, individuals you know who are allergic to gluten may also suffer from celiac disease. While this is a concern, such symptoms must be analyzed objectively, as not all individuals who are allergic to gluten have this condition.
The 100-times greater risk of having celiac disease for individuals with psoriasis has presented the opportunity for gluten-free diets to mitigate some burdensome symptoms. Celiac disease can be confirmed with a biopsy, or sample of tissue from the small intestine, but an allergy to gluten (which does not always take the form of celiac disease) can be tested for with a simple blood test. For individuals who have psoriasis and either test positive for just the blood test (indicating an allergy to gluten), or the blood test and biopsy (indicating an allergy to gluten as a result of celiac disease), it has been proven that a gluten-free diet has the ability to significantly improve psoriatic symptoms.
While this information is helpful, it must be taken with a grain of salt. Blood tests for gluten sensitivity often produce false positives, meaning that one could alter their diet unnecessarily. Another caveat to this information is that gluten-free diets have no benefit for psoriatic patients who have neither gluten sensitivity nor a gluten sensitivity due to celiac disease. This diet change has shown to produce no significant positive effects for patients with psoriatic arthritis.
Dietary Weight Reduction
It has been well recorded in medical history that there is a strong link between obesity and psoriasis. Obese patients face several burdens that can contribute to their psoriasis risk, such as a higher incidence rate of psoriasis, a decreased effectiveness for psoriasis treatment, and an increase in the severity of psoriatic symptoms. These discoveries could be very much linked to the fact that high amounts of body fat and increased inflammation in the body are the primary causes of psoriasis and psoriatic conditions.
Dietary weight reduction is when patients lose weight as a result of changes in their diet rather than through exercise or surgery. In the case of psoriatic patients, the most effective method of dietary weight reduction has proven to be a hypocaloric diet, meaning patients would consume less than the average number of calories required for people in their age category. The consumption of 800-1,400 kilocalories (kcal) is recommended for patients with a BMI of 25 or greater. Fortunately, this change in diet has been able to produce many positive effects for both patients with psoriasis and psoriatic arthritis.
Many patients have supported the use of a variety of micronutrient supplementation to improve their psoriatic symptoms. These supplements include vitamin D (both oral and topical), fish oil, selenium, vitamin B12, folic acid, magnesium and vitamins A, D, E and K among others. The only supplements that seem to possess evidence that they positively affect psoriatic patients include vitamin D and calcidiol/calcitriol.
Vitamin D can help reduce psoriasis plaque, the painful, “scaling” of the skin. Its effects are seen more immediately upon oral application, however, effects can be observed using oral vitamins with use over six or more months.
Calcidiol and calcitriol are supplementations that can be used to reduce the severity of psoriatic arthritis if 0.5 to 2.0 micrograms are taken daily.
These observations indicate that dietary supplementation has the capacity to significantly improve the quality of life.
Specific Diets, Foods or Diet Patterns
The only diets that seemed to have produced positive outcomes for patients with psoriasis include Mediterranean diets and the South Beach Diet among a few others. While these results are promising, further studies must be done to confirm the validity of this data.
The effects of psoriasis and psoriatic arthritis have great hope of being worries of the past if more multidisciplinary approaches to treatment are implemented. These approaches include the combination of changes in diet as well as medicinal approaches that one can access through their physician. Although psoriasis is a condition that is chronic, mild-to-moderate psoriasis can be treated. Using this secondary analysis of data compiled by the National Psoriasis Foundation, patients can make more informed decisions regarding psoriasis and diet, allowing communities to approach a future in which psoriasis may become easily treatable and preventable.
Written by Nikki Khoshnood, BHSc Candidate
Reference: Ford. R. A., Siegel. M., Bagel. M., Corodoro. M. K., Garg. A., Gottlieb. A., Green. J. L., Gudjonsson. E. J., Koo. J., Lebwohl. M., Liao. W., Mandelin II. M. A., Markenson. A. J., Mehta. N., Merola. F. J., Prussick. R., Ryan. C., Schwartzman. S., Siegel. L. E., Voorhees. V. S. A., Wu. J. J., Armstrong. W. W. Dietary Recommendations for Adults With Psoriasis or Psoriatic Arthritis From the Medical Board of the National Psoriasis Foundation. (June 20, 2018). JAMA Dermatology.