High salt intake linked to atopic dermatitis

Dietary sodium intake, measured through 24-hour urinary sodium excretion, is positively associated with atopic dermatitis (AD), as suggested in a study.

The study included 215,832 participants (mean age 56.52 years, 54.3 percent female, 95.2 percent White) from the UK Biobank. Researchers assessed 24-hour urine sodium excretion, estimated using a single spot urine sample, in relation to the primary outcome of AD or active AD.

Mean estimated 24-hour urine sodium excretion was 3.01 g per day, and only 23,643 participants (11 percent) had an estimated 24-hour urinary sodium excretion that was within the recommended amount of sodium intake in the UK (6 g or approximately 1 tsp of salt per day, equivalent to 2.3 g of sodium).

Applying a rigorous 3-point definition of AD, AD was diagnosed in 10,839 participants (5.0 percent), among whom 1,282 (11.8 percent of participants with AD) had active AD within 2 years of the time of urine collection. Compared with no-AD participants, those who did have AD were more likely to be female and have lower Townsend Deprivation Index (TDI) scores. AD severity was moderate in 4,813 participants (44.4 percent) and severe in 320 (3.0 percent).

In multivariable logistic regression analysis, each 1-g increase in estimated 24-hour urine sodium excretion was associated with greater odds of AD (adjusted odds ratio [AOR], 1.11, 95 percent confidence interval [CI], 1.07–1.14), active AD (AOR, 1.16, 95 percent CI, 1.05–1.28), and increased AD severity (AOR, 1.11, 95 percent CI, 1.07–1.15).

The findings were validated in a cohort of 13,014 participants from the National Health and Nutrition Examination Survey. Subsequently, each 1-g per day higher dietary sodium intake, which was estimated using dietary recall questionnaires, was associated with increased odds of current AD (AOR, 1.22, 95 percent CI, 1.01–1.47).

The present study highlights the potential of restriction of dietary sodium intake may as a cost-effective and low-risk intervention for AD.