Eduard Gerlach GmbH, Lübbecke, Germany.
SGS proderm GmbH, Hamburg, Germany.
Int J Cosmet Sci. 2023 Aug;45(4):524-538. doi: 10.1111/ics.12861. Epub 2023 Apr 27.
The use of skin care formulations with acidic pHs is seen as an effective method to maintain the acidic mantel of the skin; however, because the skin pH varies depending on the area of the body and as data are lacking for the skin pH of the feet, there was a need to examine whether this assumption holds true for skin care formulations designed for the foot. Thus, three foot creams formulated with a neutral, acidic or alkaline pH were compared with each other as well as to an untreated control group in order to analyse their impact on skin pH, hydration and general skin condition.
An exploratory clinical investigation with 60 enrolled subjects, half of whom had a diagnosis of diabetes (type 1 or type 2), was undertaken. The investigation followed a randomized, double-blind, balanced incomplete block design (BIBD) including intra-individual comparison (before and after treatment). Evaluations of skin pH and hydration were carried out using a pH meter and a Corneometer respectively. Objective evaluation of skin condition for efficacy assessment was performed by a trained grader. For tolerability evaluation, objective and subjective dermatological assessments were performed.
At the end of the treatment period, the skin pH was largely unchanged at five out of six of the test areas, with the mean value for each treatment group using test products showing similar fluctuations as the untreated control group. Furthermore, the skin condition parameters studied all improved by a comparable magnitude for each of the treatment groups using the test products, whereas the untreated control group experienced a worsening of the skin condition parameters.
The results of this investigation suggest that where the skin of the foot is concerned, the pH of skin care formulations has no (physiologically) relevant influence on the skin's pH in either diabetic or non-diabetic subjects. Furthermore, the expectation that acidic formulations would be more beneficial for the skin's condition was not found to hold true for the skin of the foot, as no significant difference was observed between the performance of the three test products investigated in this study.
使用酸性 pH 值的皮肤护理制剂被视为维持皮肤酸性覆盖物的有效方法；然而，由于皮肤 pH 值会因身体部位的不同而有所变化，而且缺乏足部皮肤 pH 值的数据，因此需要研究用于足部的皮肤护理制剂是否适用于这种假设。因此，将三种 pH 值分别为中性、酸性和碱性的足部乳膏进行了相互比较，并与未经处理的对照组进行了比较，以分析它们对皮肤 pH 值、水分和一般皮肤状况的影响。
对 60 名入组受试者进行了一项探索性临床研究，其中一半受试者患有糖尿病（1 型或 2 型）。该研究采用随机、双盲、平衡不完全块设计（BIBD），包括个体内比较（治疗前后）。使用 pH 计和 Corneometer 分别评估皮肤 pH 值和水分。通过经过培训的分级员对皮肤状况进行客观评估，以评估疗效。为了评估耐受性，进行了客观和主观的皮肤科评估。
在治疗结束时，六个测试区域中有五个区域的皮肤 pH 值基本不变，每个治疗组使用测试产品的平均值与未处理的对照组相似。此外，使用测试产品的每个治疗组的所有皮肤状况参数都有类似程度的改善，而未处理的对照组的皮肤状况参数则恶化。
本研究结果表明，就足部皮肤而言，皮肤护理制剂的 pH 值对糖尿病或非糖尿病受试者的皮肤 pH 值没有（生理上）相关影响。此外，酸性制剂对皮肤状况更有益的期望在足部皮肤中并未得到证实，因为本研究中研究的三种测试产品的性能之间没有观察到显著差异。
