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Among patients with atopic dermatitis, apple cider vinegar soaks did not enhance skin barrier integrity significantly, but did lead to skin irritation in most subjects, a pilot split‐arm study found.

Transepidermal water loss (TEWL) increased and pH declined immediately after the treatment, but the effects were not maintained 1 hour later, reported Lydia Luu of the University of Virginia in Charlottesville, and colleagues.

They said that notably, 72.7% of participants had mild side effects from apple cider vinegar with improvement after the soaks were stopped.

Further research is needed to demonstrate the true effect of apple cider vinegar in eczema, noted study co-author Richard Flowers, MD, also of the University of Virginia. "We often consider natural treatments as harmless, but our study showed that this may not necessarily be the case," he told 番茄社区. "This highlights the importance of patients reaching out to their dermatologist or provider before undertaking home remedies for their skin, to ensure they are doing them in the safest and most evidence-based manner."

Writing online in , the team noted that there were indications from recent research that diluted apple cider vinegar could improve the skin barrier integrity in patients with atopic dermatitis, but the efficacy and safety had not been well studied.

Patients use apple cider vinegar for skin infections and other maladies like warts in addition to atopic dermatitis, Luu and co-authors noted, adding: "Even some dermatologists have recently started recommending apple cider vinegar baths for atopic dermatitis."

"Future studies are needed to explore whether lower concentrations of acetic acid soaks or other applications such as a leave‐on acidic ointment would be more effective in acidifying the skin and improving skin barrier integrity in a safe, nonirritating way," the investigators concluded.

Asked for his perspective, Alexander Egeberg, MD, PhD, of Copenhagen University Hospital Gentofte in Denmark, who was not involved with the study, agreed that the results suggest that even though apple cider vinegar provides patients "very transient improvements," the clinical benefits on skin barrier function probably remain very limited.

"Currently, the use of apple cider vinegar is not standard of care, and these data do not suggest that it will change anytime soon," he added.

Study Details

For the study, the researchers evaluated 11 healthy controls (geometric mean age of 28.8) and 11 subjects (geometric mean age of 20.6) with atopic dermatitis. The participants soaked both of their forearms for 10 minutes a day for 2 weeks, with one arm in water and the other in diluted apple cider vinegar (0.5% acetic acid). TEWL and pH were measured before and after treatment.

At baseline, TEWL was significantly increased among atopic dermatitis patients (geometric TEWL mean 11.1, 95% CI 8.6‐14.3 g/m²/h) and in healthy controls (geometric TEWL mean 7.1, 95% CI 6.0‐8.4 g/m²/h). Skin pH in healthy subjects (geometric pH mean 4.86, 95% CI 4.60‐5.13) and atopic dermatitis (geometric pH mean 4.88, 95% CI 4.67‐5.10) were comparable at baseline.

Compared with baseline, TEWL in healthy and atopic dermatitis participants was significantly elevated at 0 and 15 minutes following the apple cider vinegar treatment (P≤0.01). TEWL returned to baseline 1 hour after each soak in controls and 30 minutes after each soak among atopic dermatitis patients, but TEWL was the same in both groups as at baseline 24 hours after the 14 day soak (P=0.30).

Compared with healthy participants, participants with atopic dermatitis skin had a significantly greater shift toward alkaline pH after water soak (pH 5.23 vs pH 5.54; P≤0.01), the researchers found. However, immediately after soaking in tap water with added apple cider vinegar, atopic dermatitis patients had skin pH levels similar to healthy subjects (pH 4.34 in atopic dermatitis vs 4.26 in controls; P=0.08).

Skin pH levels were still decreased 60 minutes after apple cider vinegar soaks in the controls (pH 4.85 at baseline vs 4.51 at 60 minutes) and 15 minutes after in atopic dermatitis subjects (pH 4.87 at baseline vs 4.52 at 15 minutes), but overall, pH was the same compared with baseline at 2 weeks (P=0.49).

Limitations of the study, Luu and co-authors said, included that apple cider vinegar was tested only on volar forearms, that it was limited to a single brand and dilution, and the patient sample was small. In addition, since the smell and intrinsic appearance of the apple cider vinegar used was easily identified, it was impossible to blind the investigators and participants.

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