By Helena Harvilicz
Chitosan is a natural, cationic biopolymer derived from chitin, abundantly available from shrimp and crab shells. Although it has been used in personal care products for years, such as skin lotions and shampoos, interest in the product is growing because of the industry's move toward natural products, as well as consumer awareness of chitosan as a dietary supplement for weight reduction.
"It has a couple of properties that make it useful for skin and hair care applications," notes Gordon Sargent, vice-president of quality assurance for Vanson Inc., a Redmond, Wa.-based supplier. "It's a film-forming polymer that makes a nice film on the hair or skin. It locks moisture in, so it keeps your skin moist. For hair, it rebuilds split ends, improves combability and has a nice shine to it."
Henkel's Cognis division is another supplier. That company has introduced three products of differing molecular weights. In the past, the use of chitosan was limited because of a lack of quality standards regarding size and impurities, according to Han Udo Kraechter of Cognis-Care Chemicals USA.
"By introducing three distinct chitosan products, generated from a quality production process that already starts from the strict selection of raw materials, these limitations can now be overcome," Mr. Kraechter explains. He gave a presentation, Chitosan--A Multifunctional Active Ingredient for Skin and Hair, at the In-Cosmetics USA technical conference in New York last month.
The company's three products are geared toward skin, deodorant and hair care formulations. Tests show that the skin care product, Chitosan CMF, has film-forming properties that improve skin softness and can increase water-resistance in sunscreen formulations.
Chitosan DCMF for deodorant applications has a smaller molecular weight and is suitable for sprays. It has been shown to have some antimicrobial effect, as well as aiding the adherence of perfumes. Henkel's hair care product, Chitosan HCMF, has the lowest molecular weight and forms a film upon drying that holds up under humidity and resists cracking.
Chitosan may also be appropriate for use in dentifrices. Vanson's Mr. Sargent reports interest in his products from toothpaste manufacturers. He notes "there seems to be some evidence that it promotes healthy gums and can help prevent cavities to some extent."
Another presentation at In-Cosmetics USA by W. Baschong of Ciba Specialty Chemicals suggests use in dentifrices. Mr. Baschong presented a paper authored by himself and other researchers from Ciba, the University of Basel, and Christian-Albrecht University entitled Sceroglucan and PM-chitosan--Two Cosmetic Actives Interfering with Bacterial Adhesion.
PM-chitosan is a derivative that dissolves at a moderate pH--unlike chitosan, which dissolves only at an acidic pH. "Both products, scleroglucan and PM-chitosan, reduce the adhesion of oral bacteria of hydroxyatite in vitro, indicating a beneficial interference with the formation of dental plaque. PM-chitosan additionally inhibits alkaline phosphatase, an enzyme linked to calculus and tooth decay," the paper concludes.
Although chitosan is a natural product, it is derived from animals, a concern for some toiletry manufacturers. According to Vanson's Mr. Sargent, one of his customers objected that animals were being killed to make the product. He emphasizes that crab and shrimp shells are byproducts of other industries, and chitosan is an environmentally efficient reuse of waste.
Chitosan can be obtained from fungi, but commercial suppliers process it from the anthropoid shells in cheap and plentiful supply. Therefore, another concern of consumer product makers might be shellfish allergies. Mr. Sargent says that problematic proteins or allergens should be destroyed by processing. Most supplement manufacturers note on labels that their product is derived from shellfish, but he has not heard of any allergic reactions caused by ingestion or topical applications. "And people are using it in the dietary market in a big way," he notes.