Sorbitol is a sugar alcohol that functions as a humectant moisturizer, thickening agent, fragrance ingredient, and flavoring agent in a variety of cosmetics and personal care products.
Sorbitol was first identified in the berries of a tree called the mountain ash, Sorbus aucuparia, by a French chemist in 1872. It can naturally be found in foods such as apples, pears, peaches, and prunes. Sorbitol can also be obtained by reduction of glucose, which changes the aldehyde group to a hydroxyl group. Thus, sorbitol is classified as a sugar alcohol. The majority of sorbitol is made from corn syrup. This ingredient exists as either a crystalline form or a liquid.
Sorbitol primarily functions as sugar substitute. It is about 60% as sweet as sucrose (table sugar). You can find sorbitol in diet foods, cough syrups, mints, sugar-free chewing gum, mouthwash, and toothpaste. The sweetness of sorbitol makes this ingredient useful for lip products, such as lip gloss and lip balm.
Sorbitol is also used as a humectant moisturizer in products such as creams and lotions. A humectant is a hygroscopic substance that often has a molecular structure with several hydrophilic groups. This structure allows humectants to attract and retain the moisture in the air nearby via absorption, drawing the water vapor into or beneath the surface. Due to its humectant properties, sorbitol is a useful ingredient for those with dehydrated skin.
Those with aging skin can also benefit from humectants like sorbitol since the skin naturally loses hydration with age. Dr. Mehmet Oz, MD explains that, “As we age, our skin loses some of its essential, self-moisturizing components.” The epidermis contains natural humectants collectively known as Natural Moisturizing Factor (NMF). NMF attracts and retains water inside of keratinocytes (skin cells) to aid in keeping skin hydrated. As part of the normal aging process there is a significant decrease in the amount of NMF found in the epidermis, which leads to dryness and ultimately contributes to wrinkle formation. Therefore, applying products that contain humectant moisturizers can keep skin hydrated while working to reduce signs of aging.
One problem arises with humectants, however, when they are used in extremely dry conditions. If there is little to no moisture in the surrounding air, humectants can pull too much moisture from the lower layers of skin. Unfortunately, this can leave the skin appearing dry.
As a humectant, sorbitol is often used as an ingredient in soaps, especially as an alternative to glycerin. Glycerin is another humectant moisturizer, but sorbitol is considered to be a less expensive alternative to glycerin.
Another function of sorbitol in cosmetics and personal care products is as a thickening agent. Thickeners and gelling agents in the mixtures of organic solvents and water solutions are widely applied throughout the cosmetic industry due to their ability to provide the products with the desired utility features i.e. consistency, viscosity or adhesion. The term viscosity corresponds to the concept of “thickness”, for example, honey has a higher viscosity than water. Sorbitol can support thickening effects of viscosity enhancers. Sorbitol is frequently used in gel products because of its ability to retain moisture in otherwise drying, transparent gels.
Sorbitol has been used for fifty years as a safe synthetic ingredient. The Food and Drug Administration (FDA) includes sorbitol on the list of direct food substances affirmed as Generally Recognized As Safe (GRAS). A maximum level of 99% sorbitol may be used in hard candy and cough drops, 98% in soft candy, 30% in jams and jellies, 30% in baked goods and baking mixes, 17% in frozen dairy desserts and mixes, and 12% in all other foods. Sorbitol, like other sugar alcohols, can cause digestive upset when ingested.
According to EWG, sorbitol is rated as a 1 on a scale of 1 to 10, with 1 being the lowest risk to health and 10 being the highest.
References: Wikipedia, “Sorbitol”, Truth In Aging, “Sorbitol”, Lush, “Sorbitol”, CHEMIK 2013, 67, 3, 242-249, Sharecare, “How does age affect skin’s moisture?”, Cosmetics Info, “Sorbitol”.