New research shows an association between dietary salt intake and a higher risk of developing atopic dermatitis.
- 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.”
Effects
of sodium on atopic dermatitis
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.
Other causes of
eczema
The National Eczema Foundation reports that
31.6 million people in the U.S. have some form of eczema. About 1 in 10 people
experience eczema during their lifetime.
Atopic dermatitis is
most common in children, affecting roughly 1 in 5. About 9.6 million children
under the age of 18 in the U.S. have AD, with a third of them experiencing
moderate-to severe symptoms. Roughly 7.5% of American adults, or 16.5 million
people have AD, about 40% of whom have a moderate or severe form.
Because the causes of AD
are multifactorial and vary based on the individual, it is unlikely that sodium
is the only culprit.
Abuabara cited a recent study that
identified a range of environmental factors — collectively called the
“exposome” — that may trigger the condition.
Other foods have also
been associated with developing AD, Routhenstein noted.
“Atopic dermatitis may
be triggered by different foods, depending on the person, and a food
elimination trial can help determine the potential trigger. Trigger foods can
include food additives, preservatives, dairy, wheat, eggs, fish, or shellfish,”
she said.
Routhenstein cautioned
that anyone attempting a food elimination diet to search for their AD trigger do so under the guidance of a
registered dietitian to avoid nutrient deficiencies.
Tips
to decrease dietary sodium
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.
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