, in a pilot split-arm study.
The aim of the study was to evaluate the effects of diluted apple cider vinegar application on transepidermal water loss (TEWL) and pH on skin affected by AD and on healthy skin, according to Lydia A. Luu of the department of dermatology at University of Virginia, Charlottesville, and colleagues. “Acetic acid, particularly apple cider vinegar, is prominent among emerging natural remedies used in AD. Therefore, determining the safety of this commonly used product is crucial,” they wrote in the study, published in Pediatric Dermatology.
In total, 11 patients with AD and 11 healthy controls were included; most of those with AD were considered mild (36.4%) or moderate (45.5%). Participants had not used systemic or topical antimicrobial treatments in the month preceding the study, and they were aged 12 years and older (mean ages were 20.6 years in the AD group and 28.8 years among controls). Those with AD had significantly elevated TEWL at baseline, compared with controls.
For 14 days, study participants soaked one forearm in dilute apple cider vinegar (0.5% acetic acid) and the other in tap water for 10 minutes daily. Changes in pH and TEWL before and after application were measured.
The researchers found that TEWL significantly increased immediately post treatment (at 0 and 15 minutes) in both groups, dropping to baseline at 30 minutes among those with AD and at 60 minutes among controls.
Skin pH was similar in both groups at baseline (4.86-4.88). After the cider vinegar soak, there was a transient reduction in skin pH among AD patients that lasted for 15 minutes among those with AD and 60 minutes in controls. This finding “suggests temporary acidification of the skin that has theoretical benefit of correcting disrupted skin pH in AD,” the authors wrote, noting that increased TEWL and alkaline skin pH is common among people with AD because of skin barrier dysfunction.
With respect to safety, 72.7% (16) of the participants experienced skin discomfort, mostly described as mild, limited to the vinegar-treated arm. After discontinuation, the majority of skin irritation resolved quickly, with no additional therapy.
The authors acknowledged two key limitations of the study were the homogeneous patient population and small sample size. “Although epidermal acidification would theoretically be beneficial in treating AD, our study shows that acidification by way of topical bathing in a 0.5% [apple cider vinegar] solution as performed in this study is not useful in AD treatment,” they wrote. “Further studies in a more diverse population will be necessary to fully characterize the risk/benefit profile of topical dilute apple cider vinegar treatments.”
The study was funded by the University of Virginia. The authors did not provide information on financial disclosures.
SOURCE: Luu LA et al. Pediatr Dermatol. 2019 Jul 22. doi: 10.1111/pde.13888.