The influence of diet on psoriasis is of high interest to patients, but the scientific data is limited to provide recommendations. There is strong scientific evidence that the benefit of weight loss among people with psoriasis who are obese improves disease severity and that gluten-free diets can help improve psoriasis in a subset of patients. However, for the majority of people with psoriasis, there is an absence of clinical trial data to prove the benefits of one diet over another.
Recently, a survey was conducted to understand the role of dietary behaviors in the management of psoriasis.
The objectives of the survey were:
About the survey
The survey was sent to the mailing list of the National Psoriasis Foundation, and a total of 1,206 people with psoriasis from across the U.S. completed the questions.
- 20.9% had mild disease
- 42.4% had moderate disease
- 36.9% had severe disease
The survey included 30 questions from the National Health and Nutrition Examination Survey (NHANES) dietary screening questionnaire, which assesses nutrient intake. (The 2009-2010 NHANES survey results served as the control group to compare against.) An additional 31 questions concentrated on self-reported skin responses to dietary changes, attitudes regarding diet as a management strategy for psoriasis, and demographics.
Compared to the control group, the survey respondents with psoriasis reported less daily intake of sugar, whole grain fiber, dairy products, and calcium, and a higher daily intake of fruits, vegetables, and legumes.
Forty percent of respondents reported trying a special diet to help manage their psoriasis, with the most common diets being gluten-free (35.6%), low carbohydrate-high protein (16.6%), and Paleolithic (11.6%). Across all the special diets, 69% reported they lost weight, which may contribute to the reported benefits of these diets, as weight loss has been proven through research to help reduce psoriasis symptoms among patients who are obese.
Those who reported following a special diet that experienced an improvement or clearing of their psoriasis included:
About 37% of survey respondents said they did not recognize any dietary triggers that worsen their psoriasis or left that question blank.
Of those who believed dietary factors were a trigger, the most common reported dietary triggers include:
The mechanism for how each of these triggers may worsen psoriasis is unclear, however, earlier research studies have suggested these dietary components may alter the composition of the microbiome (natural bacteria) in the intestines, irritate the intestinal lining, and impact the immune system. Several studies have also documented an improvement in psoriasis in people with celiac disease, in which the ingestion of gluten leads to damage in the intestines.
The survey also asked what dietary additives improved psoriasis symptoms. Common answers included:
B, vitamin E, vitamin C, and Tumeric
Some studies have found that complex carbohydrates with high fiber, like those found in fruits and vegetables, have a positive effect on the gut microbiome and reduce inflammation. Several research trials have evaluated the benefits of fish oil supplementation and have found fish oil to be of moderate benefit in reducing psoriasis symptoms.
Improvement of psoriasis with removal of dietary items
Many of the survey respondents reported removing certain items from their diet, such as junk foods (including candy, sweets, chocolate, French fries, and chips), white flour products, high fat foods, red meat, alcohol, gluten, dairy, tobacco, sodium/salt, nightshades (including tomatoes, eggplant, peppers, paprika, and white potatoes), caffeine, pork, or shellfish.
Those who removed the following items from their diet reported a significant improvement or clearance of psoriasis:
Improvement of psoriasis with addition of dietary items
Survey respondents also reported improvement or clearance of their psoriasis with the addition of the following items to their diet:
Perceptions about diet
The majority (43.2%) of survey respondents were not sure how diet affected their skin, but 16.7% felt their diet was significantly helping their skin and another 17.4% felt their diet was slightly helping their skin. Many reported it was somewhat difficult (39.2%) or very difficult (18.7%) to follow a special diet, but others found it not difficult (26.9%). Most respondents agreed that it is very important (64.8%) or somewhat important (24%) that their doctors discuss with them the role of diet in managing their condition.
Although the study authors admit that people who responded to the survey may have had a greater interest in the topic of diet, it is notable that the majority of respondents reported the motivation for trying dietary modifications to improve their health. While there is no cure for psoriasis, dietary changes may help some manage psoriasis flares.