Hamilton, Rowan. Strengths and Limitations of Aloe Vera The American Journal of Natural Medicine. December 1998, Vol. 5, No. 10:pp. 30-33.This Aloe vera botanical monograph reviews the broad range of therapeutic uses to which aloe is put. The degree to which these applications are substantiated by scientifically sound research varies. Two extracts of aloe have long been used therapeutically. The clear mucilaginous gel collected from the fleshy part of the leaf is taken internally (for its purported antioxidant, immune stimulant, anti-cancer and anti-viral effects) or applied topically to aid skin/wound healing and soothe irritation. A yellow latex 'originating from a double wall of vascular bundles' in the leaves and traditionally called 'bitter aloe' is used as a laxative. Bitter aloes is typically reduced by drying to a brown resinous powder. Aloe gel is used fresh or stabilized. Acemannan, a carbohydrate fraction obtained from the gel, is believed to possess the gel's properties, and 'has also been shown to have anti-viral activity,' according to this article.
Studies indicate that aloe aids in healing partial thickness (limited to upper skin layers) wounds, but that its dermal healing effects are counterproductive in 'full-thickness' wounds (such as caesarian section incisions) because the 'dermal layer . . fuse[s] too quickly,' according to this author, hindering healing in deeper layers. Aloe has been found to be effective in treating cosmetic dermabrasion, frostbite, psoriasis and eczema; studies of aloe and burns have yielded contradictory results. It is not clear here whether all of the studies cited included controls, although in some cases aloe was trialed against drug compounds. Aloe gel is widely consumed as ulcer self-medication; the author calls for more research on aloe's effects on these 'internal wounds.' Several studies support its wound healing effects after dental procedures.
A University of Texas study indicates that aloe's skin-healing properties involve stimulation of granulation tissues' collagen synthesis and maturation. Other studies (combining oral and topical administration) confirmed this effect and indicated that aloe also influences inflammation, fibroplasia (the formation of fibrous tissue), and wound contraction.
Aloe has been successfully used as a 'potentiating, biologically active vehicle for hydrocortisone,' helping reduce inflammation while 'block[ing] hydrocortisone's inhibitory effect on wound healing,' according to this author. Aloe also appears to inhibit 'the release of reactive oxygen species by human PMN (polymorphonucleocytes), reducing its harmful effects at the site of inflammation. Researchers proposed three primary mechanisms to explain these effects: first, the aloe compounds emodin, aloe-emodin, and aloin have been shown to produce salicylates when metabolized; second, another aloe constituent, magnesium lactate, is an inhibitor of histadine decarboxlyase, a compound involved in histamine formation in mast cells; third, aloe glycoprotein NY945 inhibits mast cell production of leukotrines, compounds involved with inflammation.
Aloe contains at least seven superoxide dismutases, compounds with anti-oxidant activity. Animal studies suggest chemopreventive properties for aloe; the juice appears to inhibit cancer-cell division. - Betsy Levy