Sodium intake: An emerging dietary target in psoriasis

Abstract

Psoriasis is a chronic immune-mediated skin disease primarily driven by overactivation of the Th17 immune pathway. Emerging evidence indicates that dietary factors may influence the development and exacerbation of psoriasis. Limited studies have suggested that a low-calorie, low-fat diet, along with dietary supplementation with omega-3 polyunsaturated fatty acids and vitamin D, may improve the severity of psoriasis. Additionally, reduced alcohol consumption and a gluten-free diet may be beneficial in selected patients.¹

Dietary sodium intake is a recognized risk factor for cardiometabolic disorders, including hypertension, ischaemic heart disease and chronic renal disease. It is also known that sodium from the diet can be stored in the skin. Previous studies have demonstrated increased sodium concentrations in the skin lesions of patients with atopic dermatitis.² More recently, noninvasive sodium-23 magnetic resonance imaging has shown elevated skin sodium content in patients with psoriasis (PASI >5) compared to healthy controls.³ Prior research suggests that high sodium concentrations may contribute to immune dysregulation by activating the Th17 immune pathway, offering a potential mechanism for the role of sodium in psoriasis pathogenesis.⁴ However, the association between dietary sodium intake and psoriasis has rarely been explored in epidemiological studies at the population level.

In this issue of the journal, Chattopadhyay et al. performed a cross-sectional, population-based epidemiological study using data from the UK Biobank and the US National Health and Nutrition Examination Survey (NHANES), and found that higher dietary sodium intake was associated with an increased risk of psoriasis.⁵ The primary analysis was performed using the UK Biobank database, which included 468,913 participants with and without psoriasis. Dietary sodium intake was assessed by measuring spot urine sodium concentration, and 24-h urinary sodium was estimated using the INTERSALT equation. The results showed that each 1 g increase in estimated 24-h urinary sodium was associated with an 18% higher risk of psoriasis. These findings were further validated using the NHANES database, which included 2393 participants with and without psoriasis, and also demonstrated a significant positive association between dietary sodium intake (assessed via self-report) and psoriasis risk.

This study provides valuable insights into the role of dietary factors in the development of psoriasis. By utilizing two separate population-based databases from different countries (the United Kingdom and the United States), it offers strong epidemiological evidence for an association between dietary sodium intake and psoriasis. Moreover, the study complements and supports previous smaller-scale investigations that demonstrated increased skin sodium content in patients with psoriasis.³ Although psoriasis seems unlikely to lead to higher sodium consumption, further investigations may be required to confirm the temporal relationship between dietary sodium intake and psoriasis. Future analyses should also explore the role of sodium consumption as one element of the overall diet. Indeed, other aspects of diet and lifestyle could act as confounding or moderating factors in the link between sodium consumption and psoriasis. Additionally, investigating the role of potential mediating factors (such as immune pathway activation or reactive oxygen species signalling) could help elucidate the pathogenic mechanisms underlying the relationship between sodium and psoriasis.

In summary, this study suggests that restricting dietary sodium may reduce the risk of developing psoriasis. High sodium content is commonly found in Western diets and processed foods. Further clinical trials are warranted to determine whether limiting sodium intake may serve as a low-cost, safe and broadly accessible adjunctive strategy to complement current treatment options for psoriasis. This strategy, if proven effective, may also contribute to the clinical improvement of cardiometabolic disorders, which are known comorbidities associated with psoriasis. As many patients with psoriasis seek guidance on lifestyle modifications, this study represents an important first step toward developing an evidence-based foundation for dietary recommendations.

None declared.