Psoriasis linked to ultra-processed foods

New French research has discovered a link between psoriasis and eating more ultra-processed foods (UPF).

Psoriasis is a chronic autoimmune disease, meaning it is caused by excessive activity of the immune system that attacks normal tissues in the body.

It can look a bit like eczema, causing areas of the skin to turn a different color, such as red, pink, or purple, or to become dry, itchy, and scaly.

A study published Wednesday found a significant association between active psoriasis and higher consumption of ultra-processed foods, even after adjusting for other factors such as body weight, age, gender, smoking, l physical activity and alcohol consumption.

“The study is a cross-sectional study in a French cohort, where participants who have never had psoriasis are compared to those who have active psoriasis and to those who have had psoriasis but are not currently active in terms of their dietary intakes of ultra-processed foods,” Professor Wendy Hall, from the Department of Nutritional Sciences at King’s College London, UK, said in a statement.

“This study can only tell us whether diet is associated with a health outcome, not the direction of the effect… nor whether diet actually causes a health outcome.”

She said this type of study is useful, but does not provide strong enough evidence to inform dietary guidelines.

The study authors themselves noted that further, larger-scale studies are needed to investigate the role of consuming ultra-processed foods in causing psoriasis symptoms.

In this study, French scientists used data from the Nutri-Net-Santé cohort study, collected from 2021 to 2022, involving more than 18,500 participants aged 15 or older.

Of these participants, more than 1,800 had been diagnosed with psoriasis and just over 800 had active psoriasis, meaning they were currently experiencing symptoms.

Scientists analyzed information about each person’s diet and divided them into three groups based on the amount of ultra-processed foods consumed: minimum, moderate and maximum.

They found that people with active psoriasis were more likely to be in the maximum ultra-processed food category; after adjusting for other factors, they found that this association remained significant.

The scientists concluded that this ultra-processed food could have a pro-inflammatory effect, meaning that it could promote chronic and weak activation of the immune system, and therefore the symptoms of psoriasis.

Research has shown that UPF is associated with obesity, type 2 diabetes, cancer, heart disease, and poor gut health, many of which are considered inflammatory conditions.

The article does not specify how scientists classify foods as ultra-processed. However, Hall notes that previous research by the same authors on the same cohort used the NOVA system, developed by Brazilian scientists about 15 years ago.

The NOVA system is the most widely used method for defining foods as UPF – indeed, this is how the term “ultra-processed” was coined. It defines UPF as a food produced using industrial methods, such as extrusion, and containing artificial ingredients, such as emulsifiers, that would not be available in a home kitchen.

But there is debate within the scientific community about the effectiveness of this classification.

Hall, who has ties to the food industry and has conducted research into diet and psoriasis, said: “Overall, UPF is generally a rather vague indicator of a poor nutritional profile and n It is not well defined in terms of other aspects such as additives. type or level of physical treatment.

“The majority of UPF-rated foods are also high in sugar, fat, salt, high in energy and low in micronutrients, fiber and non-nutritive bioactives, and are by definition not food groups encouraged in the Dietary Guidelines. “.

This study was supported by the French Institute of Health and the Medical Research Institutional Review Board.

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Reference

Penso, L., Touvier, M., Srour, B., Ezzedine, K., Sbidian, E. (2024). Ultraprocessed food and psoriasis, JAMA Dermatology.