Researchers study how diets affect psoriatic disease
Trying to tweak your diet to improve your psoriasis or psoriatic arthritis? If so, you are not alone, and researchers are taking note.
"We all have to eat during the day," said Dr. Wilson Liao, who recently coauthored a three-part series analyzing the effect of diet on psoriasis. "If there's a way to turn that requirement into a benefit for our health and for psoriasis, then why not?"
The series, published in the Journal of the American Academy of Dermatology, explores available research on weight loss, gluten-free diets and nutritional supplements, and their impact on psoriatic disease. More studies are needed, Liao said. "We also need more randomized, clinical trials to prove that these dietary modifications work."
Liao's research team plans to conduct a survey of psoriasis patients to learn more about their interest in different diets. Liao's research team is interested in further exploring the importance of diet in managing psoriatic disease. You can participate in Liao's research by filling out the online Diet Survey for Skin Diseases.
Researchers found several studies linking obesity to an increased risk for psoriatic disease. These studies indicate that a higher body mass index (BMI) is associated with an elevated risk for developing psoriasis and psoriatic arthritis, as well as increased disease severity.
Obesity may provide the nudge that triggers psoriasis in people who are already predisposed to it, Liao said. Previous research suggests that the development of psoriasis could be influenced by the interaction between BMI and certain gene mutations.
Researchers also found that in overweight individuals, losing weight may improve the effectiveness of treatments. Fat cells secrete cytokines, which are proteins that can trigger inflammation, explained Liao. "So if you lose weight, you may be reducing fuel for the fire."
As Liao and his colleagues report, many studies have evaluated the benefits of a gluten-free diet for psoriasis. This interest comes in large part from the association between celiac disease, which is caused by an intolerance to gluten, and psoriasis. Research suggests that having psoriasis about doubles your chance of being diagnosed with celiac disease.
Celiac disease and psoriasis both involve inflammatory immune responses, and, according to several studies, may share the same biological mechanisms. Research indicates that for people who have celiac disease and psoriasis, a gluten-free diet can help improve both diseases. In one study, 73 percent of patients with psoriasis and celiac disease who were on a gluten-free diet experienced a reduction in psoriasis severity. However, this same study found that people on a gluten-free diet who did not have celiac disease did not experience psoriasis improvement.
Liao said that so far, he has not seen any published evidence that going on a gluten-free diet can improve psoriasis in people who do not have celiac disease.
Researchers reviewed studies testing the benefits of four nutritional supplements: vitamin D, vitamin B12, selenium and omega-3 fatty acids. Of these, omega-3 fatty acids, taken in fish oil supplements, were found to offer the most benefit to people with psoriasis.
Omega-3 fatty acids can decrease overall inflammation, the authors note. Several studies found that people taking fish oil supplements, either alone or with other treatments, experienced a decrease in psoriasis severity.
Vitamin D was also shown to improve psoriasis and psoriatic arthritis. However, vitamin D can also cause serious side effects by raising the calcium level in the blood. "Sometimes that can lead to things like kidney stones and maybe even gout," Liao said.
Researchers did not find significant evidence that selenium or vitamin B12 improved psoriasis.