Atopic dermatitis: Reducing salt intake could lower eczema risk

Evan Walker
Evan Walker TheMediTary.Com |
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New research shows an association between dietary salt intake and a higher risk of developing atopic dermatitis. Sophia Hsin/Stocksy
  • Nearly 32 million people in the U.S. have some form of dermatitis, most of whom are children.
  • A new study links excess sodium intake with the development, activation, and intensifying of atopic dermatitis, or eczema.
  • When sodium is stored in the skin it can trigger inflammatory pathways that result in atopic dermatitis.
  • The study demonstrates a link between high salt intake and atopic dermatitis, but environmental factors and other causes also play a role.

Atopic dermatitis (AD), commonly known as eczema, is a collection of inflammatory skin conditions.

Symptoms of AD may include rashes, dry and scaly or cracked skin, itching, skin infections with open, weeping sores, as well as discolored skin and blisters. The condition is caused by certain triggers that vary from person to person.

Now, a new study from researchers at the University of California, San Francisco (UCSF), suggests that high levels of dietary sodium may raise the risk of developing atopic dermatitis.

The study found that people with a 1-gram increase in estimated 24-hour urine sodium excretion were 11% more likely to develop atopic dermatitis, 16% more likely to have active symptoms of existing AD, and have an 11% higher chance of increasing AD severity.

The study is published in JAMA Dermatology.

“[Atopic dermatitis] encompasses a spectrum of inflammatory processes and is triggered by various environmental factors,” Katrina Abuabara, MD, associate professor of dermatology at UCSF and senior study author, told Medical News Today. “This study was the first step in that we were able to show an association between dietary salt and AD in a large population.”

The study was a cross-sectional investigation of data for 215,832 participants in the UK BioBank aged 37 to 73, with a mean age of 56.52 years. Of this group, 54.3% were female. The cohort included 10,839 people who had AD, while the remainder did not.

Urinalysis of participants established that the mean estimated 24-hour urine sodium secretion was 3.01 grams, which represented about 90% of the previous day’s dietary sodium intake. The researchers observed that for every 1 gram of sodium above that mean, atopic dermatitis risk increased.

“It is hypothesized that sodium is stored in the skin to prevent water loss, and may help prevent infection. However, it can also activate cells in the immune system, triggering some inflammatory pathways and removing the ‘brakes’ from others,” Abuabara explained.

“For reasons we don’t yet understand, some people may be more susceptible to the effects of sodium, just as people differ with respect to their susceptibility to the effects of sodium on blood pressure. I think it is important to have experimental evidence that reducing dietary salt can actually improve eczema symptoms before we recommend dietary changes specifically for eczema.”

— Katrina Abuabara, MD, senior study author

Michelle Routhenstein, RDN, a preventive cardiology dietitian at EntirelyNourished.com, not involved in the study, noted a limitation of these findings.

She said the study involved only one urinary sample per participant, which was used to estimate urine sodium excretion for a single 24-hour time period. This estimated 24-hour sodium excretion was then used to gauge participants’ typical dietary sodium intake.

Without more samples collected over a longer term, the study’s ability to assess long-term sodium intake accurately was limited, Routhenstein said.

The findings of this new research suggest that reducing salt intake could be a simple way to prevent or alleviate atopic dermatitis.

Eliminating dietary sodium altogether is not feasible. Sodium naturally occurs in many foods, and salt, the biggest source of dietary sodium, is often added to food processing for preservation and flavor. However, Routhenstein explained that not getting enough sodium could be harmful to health.

“If you are excessively sweating or having chronic diarrhea where the loss is more than intake, it may be a concern. This can lead to fatigue, muscle weakness, nausea, vomiting, headache, confusion, and seizures,” she said.

“The other issue that may arise with a potentially no-salt diet is an iodine deficiency if you are not consuming other sources of iodine like dairy, seaweed, or fish. More concentration should be placed on what you are adding to the diet to help address inflammation and ensure nutrient adequacy,” Routhenstein noted.

Many table salts are iodized, meaning they contain small amounts of added iodine to help prevent iodine deficiency in the general population.

Routhenstein recommended that a person adjust to consuming less sodium by replacing it with other pleasing flavors.

“Adding flavor such as favorite herbs, spices, citrus juices like lemon or lime, vinegar such as balsamic or apple cider, and garlic and onions is important when reducing salt intake, ensuring dishes maintain depth and tanginess without relying solely on salt.”

— Michelle Routhenstein, RDN, preventive cardiology dietitian

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