Dietary changes can improve psoriasis

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According to a recently published report, dietary changes, used in conjunction with standard medical treatment, can help adults with psoriasis or psoriatic arthritis reduce the severity of their disease.

The report was based on a comprehensive review of the scientific literature from the Medical Board of the National Psoriasis Foundation in the USA.  The researchers took into account a total of 55 studies, representing 77,557 subjects, of whom 4534 have psoriasis. 

There were three key findings and recommendations relating to:

  1. weight loss
  2. a gluten free diet and
  3. dietary supplements.
     

Weight loss
The board found very good evidence to suggest that weight loss in those who are overweight, has a major positive impact on disease severity and quality of life.  This is best achieved by a structured low-calorie diet combined with increased physical activity.  There is nothing especially surprising about this and I have already covered the relationship between overweight and psoriasis, including psoriatic arthritis, in detail here.  

A gluten free diet
Psoriasis is linked to a more than 2-fold increased frequency of celiac disease. The review concluded that in patients with psoriasis who tested positive for gluten sensitivity, a gluten-free diet led to significant improvements in clinical severity and in skin biopsy findings after 3 months.
  
Accordingly, the board recommends a gluten-free diet trial for 3 months, but only in patients with a positive blood test for gluten sensitivity.  This is very important, because many people believe themselves to be gluten sensitive, when in fact they are nothing of the sort.  A physician diagnosis of gluten sensitivity is essential before embarking upon a gluten-free diet, which is not without its own hazards.
 
However, the board does not recommend universal screening for gluten sensitivity in adults with psoriatic disease because of the high rate of false positives.  Potential screening candidates include those with a first-degree relative with coeliac disease or patients with gastrointestinal symptoms, typical of gluten sensitivity.

Dietary supplements
I have covered the question of supplements and psoriasis in our leaflet – “Psoriatic Lifestyle and Nutrition” (available from PAPAA).  

The review board did not recommend oral fish oil supplementation because they did not regard it as effective at doses and durations studied.  My own view, however, is that fish oils have important anti-inflammatory properties and health benefits which are independent of – and in addition to – their potentially positive impact on psoriasis.  Moreover, regular consumption of oily fish is a general dietary recommendation from all expert groups.  

The review did not recommend either vitamin D or B12 supplements for prevention or treatment of psoriasis.  This seems reasonable given the lack of scientific evidence in this regard, though it is important to note that the UK Department of Health advises everyone to consider taking a vitamin D supplement (10mcg) for bone health, during the autumn/winter period.  

Author:
Dr David Ashton MD PhD

Reference:
Adam R. Ford, Michael Siegel, Jerry Bagel, et al.  Dietary Recommendations for Adults with Psoriasis or Psoriatic Arthritis: from the Medical Board of the National Psoriasis Foundation.  A Systematic Review. JAMA Dermatol. Published online June 20, 2018. doi:10.1001/jamadermatol.2018.1412