Three studies from the American Academy of Dermatology show that a topical version of glucosamine has the ability to normalize pigment overproduction in skin cells damaged by exposure to UV radiation.

“While a great deal is known about glucosamine’s safety profile and anti-inflammatory and antioxidant properties, there have been few well-controlled studies on how these properties could be used to improve skin health,” says Alexa Kimball, MD, assistant professor of dermatology at Harvard Medical School, who supervised one of the studies. “These findings could impact the way dermatologists treat UV related skin damage.”

Data from the studies focused on a formulation that contained N-acetylglucosamine, a more stable version of glucosamine. N-Acetylglucosamine is a substance that inhibits glycosylation of protyrosinase a key process in melanin overproduction in UV-damaged skin cells. The in vivo and in vitro studies highlight improvements in hyperpigmentation, skin tone, and barrier function.

Two double-blind, placebo-controlled clinical studies examined the effects of N-acetylglucosamine alone and a complex containing N-acetylglucosamine plus niacinamide, a vitamin B derivative, which has previously been shown to be effective in reducing facial hyperpigmentation.

The first study involved 50 Japanese women (ages 25–55) who were randomized to use either a topical placebo formulation or an N-acetylglucosamine formulation.

The second study involved 35 Caucasian women (ages 35–65) who were randomized to use either a topical formulation containing niacinamide or N-acetylglucosamine plus niacinamide complex. The researchers concluded that N-acetylglucosamine was more effective in reducing hyperpigmentation over the placebo and a complex of N-acetylglucosamine and niacinamide were more effective in reducing hyperpigmentation than niacinamide alone.

In the third study, 200 subjects (ages 40–60) with facial hyperpigmentation were studied. One hundred of the subjects used an moisturizing lotion with a sun-protection factor (SPF) of 15 and a moisturizing cream with an N-acetylglucosamine and niacinamide complex. The remaining 100 subjects used the lotion and cream without the active complex.

Results found that a topical N-acetylglucosamine plus niacinamide complex is clinically effective in reducing the appearance of facial hyperpigmented spots. The results also found that the combination was significantly effective on top of any effect provided by the SPF-15 sunscreen included in the daytime test products.

The 200 subjects also underwent additional testing using the SIAscope, a technology that models and measures the interaction of light within the skin to produce full-face visual maps of melanin distribution. The maps revealed that treatment with an N-acetylglucosamine and niacinamide complex resulted in a reduction in both hyper-melanized spot size and heterogeneity of melanin distribution.