Ask a Chemist: Natural vs. Synthetic Ingredients

PHOTOGRAPHY: ISTOCKPHOTO

Aren’t “natural” cosmetic ingredients safer and healthier than man-made ingredients? Louise Hidinger, PhD chemist, answers our question:

Although this is a common belief, it’s not necessarily true. First off, at the molecular level, the body cannot tell whether an ingredient comes from a natural source or a man-made source. For example, a vitamin C molecule obtained from an orange looks identical to a vitamin C molecule made in the lab.

But there are some notable differences between natural vs. synthetic ingredients:

To obtain an ingredient from plant material requires multiple steps: digesting or processing the plant material, extracting the desired ingredient with a solvent, and concentrating the extract through successive levels of purification. As a result, a large amount of plant material is needed, and the yield is usually very small. Even so, ingredients derived from natural sources are almost never “pure,” since they often contain other chemicals from the plant material, as well as chemicals used during processing. This means the chances for exposure to an allergen are much higher—and if a consumer does experience a reaction to the ingredient, it is very difficult to pinpoint what’s causing that reaction.

Apart from the issue of safety, plant extracts may contain only a small amount of a desired active ingredient. And that amount can vary enormously from one source to another, depending on the cultivar of the plant, when and how it was harvested, and how it was processed.

In comparison, synthetically produced ingredients can be made to near purity, thus greatly reducing the potential for exposure to allergens or other chemicals that may be irritating to skin. It also helps prevent over-harvesting of a naturally occurring source, which might be an endangered species. A good example of this is cetyl alcohol, a moisturizing ingredient that was originally obtained from whale oil. Many species of whales were hunted to near extinction for their oil. Now, cetyl alcohol can be prepared synthetically.

Louise Hidinger is a PhD chemist and the writer behind the website Ingredients: The Science of Beauty. Her next talk on cosmetic science will be held at the Toronto Public Library on June 25, 2015.