The Gut-Skin Connection
Research suggests a meaningful connection between gut and skin health. Research describes a reciprocal relationship in which gastrointestinal health can influence skin stability and adaptability. For example, studies by Levkovich et al. (2013) and O’Neill et al. (2016) explore the interplay between gut health and skin homeostasis.. Explore this connection further here click here.

The Body’s Natural Buffers
Blood pH, an important physiological parameter, is tightly regulated by the lungs and kidneys. These systems, along with innate buffering mechanisms, help minimize pH fluctuations and support physiological balance. For further insight, see the Merck Manual’s overview of acid–base balance here., click here.

The human body functions as a finely tuned system, continually balancing multiple variables to maintain equilibrium. These studies underscore the intricate interconnectedness of our bodily functions. This relationship highlights how closely gut health and skin health can be connected.

Changes in skin or body pH can be influenced by what we consume (food and drink), inhale (airborne substances), and apply to the skin.

The body functions as a dynamic system, continuously working to regulate internal equilibrium. Its interconnected systems operate in tandem to keep physiological processes functioning within stable ranges:

• The buffering system “uses a combination of the skin and body’s naturally occurring antioxidants, enzymes, weak acids and weak bases to minimize changes in the skin and body’s pH.” (The quote is from The Hair & Cosmetic Dermatology Center, lengthy but a great read.)

Skin pH changes throughout life, reflecting shifts in the skin’s ability to support and maintain its protective barrier. In healthy newborns, the skin surface is naturally alkaline, with pH levels ranging from 6.34 to 7.5, as noted in Skin Physiology of the Neonate and Infant: Clinical Implications. Over time, this alkalinity transitions toward the more acidic range of approximately 5 to 5.5 typically observed in adult skin. The adjustment begins as early as the second day after birth, reflecting the skin’s rapid adaptation to life outside the uterus, where amniotic fluid maintains an alkaline pH of 7.1 to 7.3.

With advancing age, the skin’s capacity to regulate surface pH may gradually decline. Some studies suggest that by around age 50, epidermal pH may begin to rise, with further increases observed in older age groups (source click here).

These changes may reflect age-related shifts in the efficiency of skin barrier and pH-regulating processes.

Exposure to external factors—particularly substances with a higher pH than the skin surface—can temporarily shift skin pH upward. For example, standing under a shower with tap water—which in the U.S. typically has a pH around 7—causes can cause a temporary increase in the skin’s surface pH. However, this is not necessarily a cause for alarm. Unless an individual experiences specific skin sensitivities or conditions, there is no need to avoid showering or invest in filtration systems solely for this reason.

After gifting my 93-year-old aunt the soap I had made, she asked if she could use it on her face. She shared how much she enjoyed the gentle feel of the soap and its luxurious lather. Since we use our soap all over, including on our faces, I told her she certainly could. She was delighted to hear this and continued using it with great satisfaction. Her feedback added to my own observations about how well-balanced handcrafted soap can feel on aging skin.

Long-Term Effects of Soap on Skin pH Regulation

A study titled The Long-Term Use of Soap Does Not Affect the pH-Maintenance Mechanism of Human Skin examined whether long-term soap use affects the skin’s ability to regulate pH.

The Resilience of Healthy Skin pH

A common belief is that soap-based cleansers permanently disrupt the skin’s natural pH and weaken its protective barrier. However, a long-term study comparing soap-based and mild-acidic cleansers provides a different perspective. This study observed two groups—one using soap-based cleansers and the other using mild-acidic cleansers, both for over five years. Skin pH was measured before cleansing, immediately afterward, and for six hours post-cleansing.

The results showed no statistically significant difference between the two groups in terms of baseline skin pH, pH immediately after cleansing, or the pH recovery rate. These findings suggest that healthy skin can maintain its pH-regulating ability following cleansing, regardless of whether a soap-based or mild-acidic cleanser is used.

What Does This Mean for Soap Users?

For individuals with healthy skin, this study indicates that long-term soap use does not compromise the skin’s ability to regulate surface pH. While marketing materials often emphasize the advantages of mild-acidic cleansers, these findings highlight the resilience of human skin and its ability to recover naturally after cleansing.

Context Matters
It’s important to note that this research focuses solely on pH. Other factors, such as skin hydration, lipid composition, or microbiome diversity, were not addressed. For those with specific skin concerns or conditions, exploring how various cleansers affect other aspects of skin health remains essential.

The study challenges claims that soap’s alkaline nature permanently damages the skin’s pH balance, highlighting that these concerns are often unfounded marketing tactics by non-soap companies.

• Objective: To compare the effects of long-term use of soap-based (true soap) cleansers and mild-acidic (synthetic) cleansers on skin pH.
• Method: Two groups of participants were studied: one using soap-based cleansers for over five years and the other using mild-acidic cleansers for the same duration. Researchers measured skin pH on the inner forearm before cleansing and periodically for six hours afterward.
• Findings:
  • No significant differences were observed in pre-cleansing skin pH, immediate post-cleansing pH, or the rate of pH recovery between the two groups.
  • These findings suggest that long-term use of true soap does not impair the skin’s pH-regulating mechanisms in healthy skin.

Healthy human skin typically has a surface pH of around 5. Cleansing with soap temporarily raises this pH, but it naturally reverts to a more acidic state within hours. The long-term impact of using soap on the skin’s ability to regulate its pH, however, has remained a topic of debate.

Source: “The Long-term Use of Soap Does Not Affect the pH-Maintenance Mechanism of Human Skin,” Y. Takagi, K. Kaneda, M. Miyaki, K. Matsuo, H. Kawada, H. Hosokawa, First published: 30 July 2014. Affiliation: Kao Corporation, Tokyo, Japan. PMID: 25073884 / DOI: 10.1111/srt.12170

In this study, long-term use of true soap did not interfere with the skin’s natural pH-regulating processes in healthy individuals.

Cleansing without compromise: the impact of cleansers on the skin barrier and the technology of mild cleansing

• PMID: 14728695
• DOI: 10.1111/j.1396-0296.2004.04s1002.x

Cleanser technology has evolved greatly, shifting from basic cleansing to providing added benefits like mildness and moisturization. The findings in this material resonate with my own experiences, particularly in understanding why I struggled with transepidermal water loss (TEWL) for most of my life. Research indicates that some harsh surfactants can damage skin proteins and lipids, which may lead to tightness, dryness, barrier disruption, irritation, and itching after washing. I switched to using shampoo, which typically contains milder surfactants designed for hair rather than skin, but even then, it was not gentle enough to prevent dryness for me.

For synthetic cleansers to offer skin-care benefits, they must first minimize damage to skin proteins and lipids. Next, they must deliver beneficial agents like occlusives, skin lipids, and humectants under washing conditions to improve hydration and skin properties. I prefer to superfat my soap, meaning I leave a tiny amount of unreacted oils in my soap to gently nourish my skin while washing. At first, this small amount of slip felt unusual, but now I don’t even notice it. Unlike many synthetic detergents, which are continually reformulated to reduce lipid disruption, my handmade soap has proven compatible with my skin and does not leave it feeling dry or tight. Plus, it brings that spa-like experience to my home—beautiful to look at and scented with fragrances that don’t trigger my allergies or asthma. Soap, unlike synthetic cleansers, naturally contains glycerin (a humectant), a byproduct of the saponification process.

Mildness enhancers and moisturizing agents such as lipids, occlusives, and humectants are often added to synthetic cleansers to reduce damaging interactions with skin proteins and lipids. However, in my case, I have not needed these additives, as my soap contains a small superfat and naturally occurring glycerin.

Based on my experience, I had to decide whether to continue using synthetic detergents that coincided with worsening TEWL, or to use traditional soap, which my skin tolerated far better. For me, traditional soap was the better choice.

A common question arises: does washing with alkaline, true soap harm the skin’s acidic mantle?

• Exposure to Higher pH: When exposed to substances or conditions with a higher pH, such as tap water (average pH 7 in the USA), the skin’s acidic mantle temporarily shifts upward. However, this does not mean showering should be avoided or that water filtration is necessary unless an individual experiences specific skin sensitivities or conditions.
• Skin’s Recovery Ability: Unlike hair, skin can recover and return toward its typical surface pH after temporary changes.

A reasonable assumption might be that true soap, with its higher pH, would elevate the skin’s pH. However, does this temporary rise lead to lasting damage or impair the skin’s ability to recover?

Skin, unlike hair, can recover and return toward its typical surface pH after temporary exposure to substances that raise pH levels.  Depending on the duration of exposure and the degree of pH change, this recovery process may take several hours. It would stand to reason, then, that washing with alkali/true soap would increase skin’s acidic mantel. But, does this rise cause irreparable damage to the epidermis to where it cannot rebalance itself?