The Salt Factor: How Sodium Impacts Skin Health in Eczema

Original Article: Sodium Intake and Atopic Dermatitis

What are the key takeaways of this article?

In a recent study published in JAMA Dermatology, Chiang and colleagues delved into the intriguing connection between dietary sodium intake and the prevalence of atopic dermatitis (AD). AD is a widespread and challenging skin condition that impacts millions of individuals around the globe, yet the influence of diet, especially sodium, on its onset and severity remains largely unexplored. The authors’ work aims to bridge this knowledge gap by investigating whether higher sodium consumption correlates with an increased risk, heightened activity, and greater severity of AD.

Conducted as a cross-sectional study, the study analyzed data from 215,832 adults aged 37-73 years from the UK Biobank cohort. Sodium intake was estimated through 24-hour urine sodium excretion, derived from spot urine samples using the INTERSALT equation. This equation considers factors such as body mass index (BMI), age, and urine concentrations of potassium, sodium, and creatinine. The study's primary outcome was the presence and severity of AD, identified through diagnostic and prescription codes from electronic medical records.

The results demonstrated a significant association between higher sodium intake and increased odds of AD. Specifically, a 1-g increase in estimated 24-hour urine sodium excretion was linked to an 11% higher likelihood of AD diagnosis, a 16% higher likelihood of active AD, and an 11% higher likelihood of increased AD severity. These findings were validated in a cohort from the National Health and Nutrition Examination Survey (NHANES), where a dietary sodium intake higher by 1 g per day was associated with a 22% higher risk of current AD.

The implications of this study are substantial, suggesting that dietary sodium restriction could be a cost-effective and low-risk intervention for managing AD. Given that sodium is stored in the skin and associated with immune activation, these findings align with previous research indicating that sodium can drive inflammatory responses characteristic of AD. However, the authors acknowledge limitations, including reliance on single spot urine samples for sodium estimation, which may not accurately reflect long-term intake. Additionally, while the UK Biobank sample is large, it predominantly includes White European participants, potentially limiting generalizability. The study also notes that sodium intake might serve as a proxy for other dietary factors linked to AD.

Regardless, this study provides compelling evidence that higher dietary sodium intake is associated with increased prevalence and severity of AD. It opens new avenues for research on dietary interventions in AD management and highlights the importance of considering diet in understanding and treating patients with AD.

Publication Date: July 14th, 2024

Reference: Chiang BM, Ye M, Chattopadhyay A, Halezeroglu Y, Van Blarigan EL, Abuabara K. Sodium Intake and Atopic Dermatitis. JAMA Dermatol. Published online June 05, 2024. doi:10.1001/jamadermatol.2024.1544

Summary By: Parsa Abdi, Memorial University