“Natural” soap might be damaging your skin

Skin Cleansing without or with Compromise: Soaps and Syndets

Humans might have been cleansing for thousands of years, but the cleansing products at our disposal were not always the kindest to the skin. This is because, while traditional soaps might do a good job of cleansing, their chemical properties can upset the skin's protective layer. The answer to this was the development of syndets—or synthetic detergents—a gentler alternative that supports the skin's natural structure and protective role. Even so, soap-based cleansers are often considered "natural", and by association perceived as safer than synthetic cleansers.

Soaps were used by many ancient civilizations. According to a Roman legend, soap-making began on Mount Sapo, where animal fat and plant ash were mixed with rainwater to create a washing solution. By the 10th century, soap-making was common in Europe, but it was a luxury for the rich. It wasn’t until the 19th century that soap was widely available. Traditional soap is made through a process called saponification (which translates to “conversion into soap”). During this process, animal or plant-based fats (which contain fatty acids) are mixed with a strong base (alkaline chemical), creating surfactant molecules. This process results in a product with a high pH. pH is a scale (between 1-14) that measures how acidic or basic a substance is, with lower numbers being acidic, higher numbers being basic, and 7 being neutral. Syndets are a more recent invention and have been around for about 100 years. They became popular after the 1940s, when people started seeking gentler hygiene products with fewer side effects on the skin’s protective layer. Because syndets are synthetic surfactant molecules made in a lab through different processes that do not involve saponification, they have a lower pH.

Even though soaps and syndets are made differently, both types of cleansers contain surfactants— molecules that have both water- and oil-loving parts—allowing them to dissolve excess oil and other impurities by mixing them with water in order to be rinsed off. The important difference between soaps and syndets is their pH. The skin has a slightly low (or acidic) pH, while soap has a higher (or alkaline) pH. On the other hand, syndets are closer to the skin's natural pH. This means soaps don't match the skin's pH, but syndets do, making them gentler on the skin. Studies have shown that alkaline soaps can negatively affect the skin’s natural structure and function making pH an important factor in cleanser choice.

This review helps us understand that while traditional soaps and syndets both cleanse the skin, the high pH of soaps does not match the pH of skin which can cause damage to the skin over time—an example of the common conception that ‘natural’ products, like soap, are better or safer than synthetic products like syndets.

For further information read the full paper.