- People eating diets high in ultra-processed foods are more likely to have active cases of psoriasis, according to a new research letter.
- This research appears to be the first to link these foods with psoriasis flareups, whose causes are not yet fully understood.
- When the authors of the letter accounted for other factors suspected of triggering psoriasis, the association between ultra-processed foods and flare-ups remained robust.
Consuming ultraprocessed foods is strongly associated with flareups of psoriasis, according to a new research letter.
The research letter, which depended on self-reported dietary and psoriasis symptoms data, found that high consumption of ultra-processed foods, or UPF, corresponded closely to having active cases of psoriasis.
The researchers drew their conclusions from a cross-sectional study of data from the NutriNet-Santé cohort study conducted between 2021 and 2022 in France. There were 18,528 participants in the study, ages 62–70. Of these, 74% were women and 26% were men.
After the letter’s authors adjusted their findings to account for confounders such as body mass index (BMI), age, alcohol consumption, and comorbidities, the association between UPF and active psoriasis remained strong in the self-reports.
The research letter states that no association with UPF was observed for participants whose diagnoses were validated by dermatologists.
The data suggests, say the authors, that UPF contributes a psoriasis-aggravating, pro-inflammatory effect separate from the previously documented similar effect of having a high BMI.
After adjustments for age, body mass index (BMI), alcohol intake, and comorbidities, the results remained significant, suggesting that ultra-processed food intake has a pro-inflammatory action separate from high BMI.
The study is published in
Ultra-processed foods constitute a significant portion of the modern American diet. Such foods are designed for inexpensive mass production, sacrificing Healthfulness for low cost, flavor, and convenience.
UPF are high in oils, fats, sugars, and proteins derived from natural foods and are rich in modified starch and hydrogenated fats, along with food coloring and flavor enhancers. They typically contain five or (many) more ingredients.
Examples of UPFs include sausages and similar types of processed meats, sweetened drinks, sweetened yogurts, sodas, hamburgers, and breakfast bars.
Lawrence Green, MD, FAAD, of the Aesthetic Dermatology Center in Rockville, Maryland, was not involved in the research letter. He said, “To my knowledge, this is the first time I have read about an implication [connecting UPF and active psoriasis].”
“But it makes sense based on current knowledge of how high BMI, hypertension, diabetes, etc. are associated with someone having worse psoriasis. If it is true that a high UPF diet can contribute to the aforementioned comorbidities, it could also indirectly (or possibly directly) worsen psoriasis,” Green said.
“Emerging evidence highlights the role of ultra-processed foods (UPF) in exacerbating psoriasis through multiple mechanisms,” noted Rachel Day, MD, FAAD, Vice President of Zest Health in Menlo Park, California. (Day was also not involved in the letter.) “These foods are often high in refined sugars, unhealthy fats, and additives, and promote systemic inflammation, which can trigger psoriatic flares.”
“UPF also disrupt the gut microbiome and may influence epigenetic mechanisms, altering gene expression and potentially accelerating disease activity in genetically predisposed individuals,” pointed out Day.
“The low-fiber content and additives in ultra-processed foods (UPF) may disrupt gut microbiota, decreasing beneficial bacteria and increasing gut permeability, also known as ‘leaky gut’. This allows endotoxins, such as lipopolysaccharides (LPS) to leak into the bloodstream, triggering immune responses that amplify systemic inflammation and worsen psoriatic symptoms,” explained Day.
“Additionally,” Day said, “the regular consumption of UPF is
Another expert, who was not involved in the research letter is Daniel Glass, consultant dermatologist at The Dermatology Clinic in London, UK, said he was struck by an issue with the self-reported nature of most of the data upon which the letter’s conclusions are based.
“It’s interesting that the paper shows a correlation between UPF intake and psoriasis only in self-diagnosed psoriasis cases. When a calculation includes dermatologist-diagnosed psoriasis, then the association with UPF intake is no longer statistically significant,” said Glass.
“Psoriasis arises from a complex interplay between genetic predisposition and environmental factors. While much attention has been given to triggers like stress or infections, the role of nutrition — specifically, the consumption of ultra-processed foods (UP) — is often overlooked,” Day explained.
“UPFs contain chemical additives and preservatives that may influence gene expression, particularly in individuals with a family history of psoriasis,” she said.
“These dietary exposures may accelerate the onset of psoriasis in genetically susceptible individuals, potentially contributing to the observed trend of earlier disease onset compared to previous decades. Furthermore, for those already diagnosed with psoriasis, the intake of UPF can exacerbate disease activity,” she added.
“The authors do not postulate a mechanism of action but just make an inference based on their analysis. I would like to see more direct research implicating UPF other than indirect evidence through a patient survey,” Green noted.
“As the authors comment, more large-scale research is required into this interesting area, preferably with dermatologist-confirmed cases of psoriasis, and more detail on how UPF intake is classified in future studies. Further research needs to be undertaken into what are potentially modifiable risk factors for common skin diseases,” Glass said.
“With over 70% of the immune system residing in the gut, understanding the link between UPF, the gut microbiome, and immune triggers is crucial. Gut microbiome analysis could reveal molecular mechanisms by which UPF exacerbate inflammation, offering strategies to mitigate these effects,” Day added.
