11 December 2024

Ultra-processed food linked to active psoriasis

Nutrition Psoriasis

The findings have been welcomed, although more research is needed to understand the role of diet in the disease.


French researchers have found a link between high intake of ultra-processed foods and active psoriasis. 

And while they say more research is needed to understand the role of diet in the development and flare-ups of psoriasis, leading Australian dermatologist Associate Professor Stephen Shumack has welcomed the findings. 

“It’s interesting,” he told Dermatology Republic

“There’s always a lot of discussion amongst the general community about diet and skin conditions. There’s always the talk about chocolate and acne, and you know, there’s issues about high GI food and acne. 

“There’s been, over the years, relatively small studies, which have demonstrated a bit of a link.” 

The research builds on the idea that diet affects inflammation, which is a key factor in diseases like psoriasis. While the link between ultra-processed foods (UPFs) and other diseases (such as diabetes, cancer and heart disease) is known, its connection to psoriasis had not been explored before. 

“Results of this study showed an association between high UPF intake and active psoriasis status,” the authors wrote. 

“After adjustments for age, BMI, alcohol intake and comorbidities, the results remained significant, suggesting that UPF intake has a proinflammatory action separate from high BMI.” 

Their study, published as a research letter in JAMA Dermatology, used data from the Nutri-Net-Santé cohort, with participants ranging in age from 15 years and up. They were asked about their psoriasis status – whether they had it, whether it was active or whether they had never had it.  

Participants’ UPF intake was categorised into three levels based on how much they consumed. The study considered several factors like age, sex, education, lifestyle habits, body mass index and other health conditions (such as heart disease or diabetes) that could influence the results. 

The researchers did not specify exact detail of what constituted UPFs for the purposes of this study. 

The results showed that people with active psoriasis tended to eat more UPFs than those without the condition. This link remained even after adjusting for other factors, suggesting that high UPF intake may contribute to inflammation, separate from factors like obesity. 

Professor Shumack said there was relatively low-level evidence showing a link between UPF and “quite a number of inflammatory diseases like diabetes, the various types of cancer, cardiovascular, cardiovascular disease and inflammatory bowel disease”. 

“There’s always that supposition about psoriasis, which is also an inflammatory disease,” he said. 

“So it’s interesting, they’ve looked at large numbers of potential study subjects … then they’ve got an odds ratio of about 1.36 which is, significant, but not hugely significant. So that’s certainly worth further study, as they mention.” 

Professor Shumack said it was important to note that the cross-sectional observational study design prevented the researchers from ascertaining whether, elevated UPF intake preceded or was a consequence of psoriasis flare ups. 

“That’s actually a very good statement, because what we find anecdotally in practice, is people with relatively significant psoriasis tend to be a bit more obese,” he said. 

“They tend to drink more alcohol; they tend to binge drink to a certain extent. And I know they’ve tried to take obesity and those sort of things into account with this analysis, but it would be very interesting to know what came first – the ultra-processed food making it more likely to get more active psoriasis, or because you’ve got more active psoriasis, are you more likely then to binge a bit on the ultra-processed food? 

“That is a question which only a randomised control study will pick up the answer to. But a lot of people will be interested in this potential association, and any potential association which will get people to eat better, I think is worthwhile.” 

JAMA Dermatology 2024, 27 November 

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