What Is It: Aspen Bark Extract
Aspen bark extract is derived from the quaking aspen tree common to northern and western North America. For centuries, Native American Indians have used Aspen tree bark for various medicinal purposes, from treating burns to reducing fevers to relieving eczema. The bark is rich in salycin, an aspirin-like substance, which is considered to be analgesic, anti-inflammatory, calming, and healing. For treating lower back pain, the recommended dose is 1-3 grams of aspen bark, which contains 60-240 mg of salicylates.
Though they are traditionally used as analgesics, these salicylates can be easily extracted without harm to the tree, then isolated and applied to cosmetic products as natural preservative systems. The same compounds that function as the plant's natural defense mechanism from invading parasites, such as mold and yeast, demonstrate preservative properties in cosmetic formulations. Aspen bark extract has shown to effectively inhibit the growth of mold, yeast, e coli, S aureus, subtilis, and P aeruginosa. And it has the added benefit of imparting a silky and smooth feeling to skin.
Aspen bark extract appears to be an excellent alternative to traditional preservatives that are now under suspicion, such as formaldehyde donors, isothiazolones, and parabens. Natural preservative systems are limited in that their efficacy is formulation-dependent. The Tinosan SDC silver-based preservative, for instance, cannot be used in highly cationic systems. Other causes for concern in natural preservatives are consistency, color, and odor.
Aspen bark does not seem to suffer from these shortcomings, especially if used in formulas that are not water-based. All of the John Masters Organics products that I've been testing smell wonderful and lend a nice texture. The first ingredient listed on each product is aloe vera leaf juice, not water. Although aspen bark extract probably won't ward off microorganisms in watery lotions and creams, it shows enormous promise for the future of natural preservative systems.