Sodium intake may increase the risk of dry, itchy skin, study finds

According to the French Institute of Health and Medical Research, INSERM, atopic dermatitis, also known as atopic eczema, is “a chronic inflammatory skin disease, … characterized by dry skin associated with eczema-like lesions (redness and itching, vesicles, oozing and crusting) that develop in flare-ups.” The scientific research organization points the finger at genetic and environmental factors, and also mentions the impact of this kind of condition on mental health. For several years, numerous scientific studies around the world have been reporting an increase in the number of cases of this chronic disease, particularly in industrialized countries, in connection with environmental changes and lifestyles.

This finding led a team of researchers from the University of California, San Francisco (UCSF) to investigate the impact of an everyday ingredient on skin dryness and itching, and more broadly on eczema. To do this, they analyzed data from 215,832 adults aged 37 to 73 from the UK Biobank, a large-scale, long-term study conducted in the UK to assess the influence of genetic predisposition and environmental exposure on the development of numerous diseases.

Urine samples and electronic medical records were analyzed for this research. The aim was to determine the amount of sodium, a component of salt, consumed by the participants, and to correlate this data with a possible diagnosis of atopic dermatitis. Published in the journal JAMA Dermatology, their research shows an increased risk of eczema diagnosis (+11%), eczema cases (+16%) and chronic disease severity (+11%) for each additional gram of sodium excreted in the urine over a 24-hour period. [1]

Half a teaspoon of table salt

To support these findings, the researchers examined data from another population, namely 13,014 American adults from the National Health and Nutrition Examination Survey. And the findings were similar: consuming an extra gram of sodium per day — the equivalent of half a teaspoon of table salt — was associated with 22% higher odds that someone would have an active case of eczema. The authors of this study therefore advise patients to limit their salt intake to better manage eczema flare-ups.

“Most Americans eat too much salt and can safely reduce their intake to recommended levels,” says Katrina Abuabara, MD, associate professor of dermatology at UCSF, quoted in a news release. “Eczema flares can be difficult for patients to cope with, especially when they are unable to anticipate them and don’t have recommendations on what they can do to avoid them.“

According to data shared by the National Eczema Association, more than 31.5 million people in the United States have some form of eczema, or around 10% of the population.