For countless Americans, myself included, aloe vera was the first encounter with a medicinal herb. As teenagers in coastal Maine, my friends and I would head for the beach on a warm spring day to start renewing our suntans, and after frying our pallid winter skin, we'd rub aloe gel on each others' blistered backs.
Aloe gel is perhaps the most widely recognized herbal remedy in the United States today, used to relieve thermal burn and sunburn, promote wound healing, and moisturize and soften skin. Everyone who uses it seems convinced that it works, and its millennia of use for the same conditions support that assumption. In addition, recent research suggests that aloe gel can help stimulate the body's immune system. However, the way aloe works is not yet fully understood.
In the mid-1930s, researchers enthusiastically reported quick and complete healing of skin burns caused by X-rays and ultraviolet and gamma rays. The public became aware of their findings in Gertrude B. Foster's classic, Herbs for Every Garden (Dutton, 1966). Foster also noted that aloe was grown as a landscape plant in the tropics and as a houseplant in temperate climates. Although commercial development of aloe vera was already under way, its popularity exploded in the 1970s.
Two products in current use are derived from aloe leaves. The clear gel that forms naturally in the hollow interior of the leaf is the familiar product used to relieve burns and wounds, whereas specialized resin canal cells in the thick leaf epidermis produce a bitter yellow juice that is the source of the laxative drug aloe. Although they share certain components, these two products are distinctly different and should not be confused.
The conventional pharmaceutical approach to the question "How does it work?" is to determine which individual chemical component of a plant is contributing to its healing activity. This opens the door to commercial extraction and refinement--processes that can be patented. In regard to aloe, however, investigation hasn't yet provided clear-cut answers. The gel comprises more than seventy-five compounds, including polysaccharides (complex carbohydrates), steroids, organic acids, enzymes, antibiotic agents, amino acids, and minerals. One enzyme found in aloe gel has been suggested as the primary component responsible for the gel's ability to heal burns.
Since the first clinical trials of the gel in the mid-1930s, subsequent trials have produced similar, positive results. However, evidence from those experiments and from many favorable case histories is inconclusive because much of the work suffered from poor experimental design and small test samples. Although recent, more thorough research has confirmed the likelihood of useful physiological effects, the gel's properties still haven't been ascribed to specific components. Among some of the recent findings:
Researchers at Tokyo Women's Medical College in Japan have shown that certain lectins (a type of protein) in aloe gel may stimulate the immune system to increase production of killer cells, or naturally occurring lymphocytes that kill bacteria and tumor cells.
Studies in Japan and the Netherlands suggest that constituents in aloe gel can enhance the workings of the immune system by containing the killer cells' lethal chemicals, preventing them from damaging healthy, functional cells.
A research group at the University of Texas Health Science Center in San Antonio is studying the effects of aloe extracts on normal and tumor cells in humans. Although aloe probably will not emerge as a new cancer drug, such experiments provide more information on how aloe gel heals wounds and burns.
A review of the medical literature by a group at the University of Texas in Galveston concluded that aloe gel clearly promotes wound healing and prevents progressive skin damage caused by burns and frostbite. It works by penetrating injured tissue, relieving pain, reducing inflammation, and dilating capillaries to increase blood flow to the injury.
A review of the scientific literature on aloe shows that while many cosmetics containing aloe claim to stop the aging of skin, they actually only moisturize it, thereby temporarily diminishing blemishes. However, aloe vera extracts have the potential--as yet undemonstrated--to stimulate synthesis of collagen and elastin fibers, which could stop the degenerative skin changes associated with aging.