Adherence to the Mediterranean Diet and Severity of Psoriasis

• The Mediterranean diet has been associated with reduced chronic systemic inflammation and a lower incidence of chronic inflammatory diseases such as rheumatoid arthritis and Crohn’s disease. The authors of this study used a Web-based questionnaire to identify 3557 individuals with psoriasis. They compared the MEDI-LITE score, which reflects the level of adherence to the Mediterranean diet, with the severity of psoriasis. They found that individuals with severe psoriasis had a lower MEDI-LITE score, corresponding to less adherence to a Mediterranean diet, compared with those with non-severe psoriasis and those who were psoriasis-free.
• After adjusting for sociodemographic variables and potential confounders, this study revealed a statistically significant inverse association between adherence to a Mediterranean diet and the severity of psoriasis. Although these data support the hypothesis that the Mediterranean diet may be associated with less severe psoriasis, similar to its proven effect in other inflammatory disorders, randomized controlled trials will be needed to prove any existence of a direct, causal relationship and to elucidate the mechanism of the observed relationship.

  – Caroline Crabtree, MD

Written by Abby S Van Voorhees MD
We’ve all been there. You’ve just finished telling your patient with severe psoriasis that she needs a systemic therapy, and she asks you, “Isn’t there a way I could just handle my psoriasis by a change to my diet and skip the medication?” For years I would simply shake my head: “No!” Articles like this one are joining a growing chorus that is challenging that point of view. We are realizing that psoriasis is a disease of inflammation, and our patients are often overweight. We’ve also learned that psoriasis patients who are overweight have a greater likelihood of developing more severe disease and that being obese increases the likelihood of developing psoriasis. Finally, weight reduction lessens the impact of psoriasis on a patient.

In this article, Celine Phan and coauthors examine the impact of eating a Mediterranean diet, which is low in fats, on psoriasis. They demonstrate an inverse association with dietary compliance and disease severity as well as disease onset. This held up even when controlling for various factors such as cardiovascular disease, depression, and socioeconomic variables. However, before you go running to tell all of your psoriasis patients to adopt a Mediterranean diet, we need to think about the limitations of this study. First of all, this study’s conclusions are based on a very small sample size (N = 45); a larger trial is needed to substantiate these findings. We also need to be sure that it is the diet itself, not any associated weight reduction, which is the key factor. So, although this study is encouraging, it may be a bit too soon to be championing diet control for our patients with severe psoriasis.

Abstract
This abstract is available on the publisher’s site.

IMPORTANCE
Psoriasis is a chronic inflammatory disease. The Mediterranean diet has been shown to reduce chronic inflammation and has a positive effect on the risk of metabolic syndrome and cardiovascular events. Thus, we hypothesized a positive effect on the onset and/or severity of psoriasis.

OBJECTIVE
To assess the association between a score that reflects the adhesion to a Mediterranean diet (MEDI-LITE) and the onset and/or severity of psoriasis.

DESIGN, SETTING, AND PARTICIPANTS
The NutriNet-Santé program is an ongoing, observational, web-based questionnaire cohort study launched in France in May 2009. The present study was performed within the framework of the NutriNet-Santé program, with data collected and analyzed between April 2017 and June 2017. Patients with psoriasis were identified via a validated online self-completed questionnaire and then categorized by disease severity: severe psoriasis, nonsevere psoriasis, and psoriasis-free. Data on dietary intake (including alcohol) were gathered during the first 2 years of participation in the cohort to calculate the MEDI-LITE score (ranging from 0 for no adherence to 18 for maximum adherence). Potentially confounding variables (eg, age, sex, physical activity, body mass index, tobacco use, and a history of cardiovascular disease) were also recorded. Analyses used adjusted multinomial logistic regression to estimate the risk of having severe psoriasis or nonsevere psoriasis compared with being psoriasis-free.

RESULTS
Of the 158 361 total NutriNet-Santé participants, 35 735 (23%) replied to the psoriasis questionnaire. The mean (SD) age of the respondents was 47.5 (14.0) years; 27 220 (76%) of the respondents were women. Of these 35 735 respondents, 3557 (10%) individuals reported having psoriasis. The condition was severe in 878 cases (24.7%), and 299 (8.4%) incident cases were recorded (those arising more than 2 years after participant inclusion in the cohort). After adjustment for confounding factors, a significant inverse relationship was found between the MEDI-LITE score and having severe psoriasis: odds ratio (OR), 0.71; 95% CI, 0.55-0.92 for the MEDI-LITE score’s second tertile (score of 8 to 9); and OR, 0.78; 95% CI, 0.59-1.01 for the third tertile (score of 10 to 18).

CONCLUSIONS AND RELEVANCE
Patients with severe psoriasis displayed low levels of adherence to the Mediterranean diet; this finding supports the hypothesis that the Mediterranean diet may slow the progression of psoriasis. If these findings are confirmed, adherence to a Mediterranean diet should be integrated into the routine management of moderate to severe psoriasis.

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Journal Abstract