Aloe Vera: Gel, Latex and the Science of a Time-Honoured Healing Plant

Aloe vera has been a trusted healing plant across many traditions. Its leaf yields several distinct preparations: the *exudate* (a thick, yellow, bitter residue), the *gel* (the clear mucilage from the inner parenchymal cells of the leaf), and diluted gel known as *aloe vera extract* or *aloe juice*. Aloe extract is mostly water (around 99%) plus mono- and polysaccharides — most importantly the monosaccharide mannose-6-phosphate and the polysaccharide glucomannan, long-chain sugars of glucose and mannose. The gel also contains lignans, saponins, salicylic acid, sterols and triterpenoids; vitamins A, C, E, B12, thiamine, niacin and folic acid; and minerals including sodium, calcium, potassium, manganese, magnesium, copper, chromium, zinc and iron. Fresh gel contains glutathione peroxidase, isoenzymes of superoxide dismutase, and the proteolytic enzyme carboxypeptidase, along with malic-acid-acylated carbohydrates — and shows potent anti-inflammatory and anti-proliferative effects. **Wound healing.** Aloe has been shown to inhibit thromboxane, while its enzymes help break down damaged tissue for removal by phagocytosis. A glycoprotein fraction increases proliferation of human keratinocytes and the expression of epidermal-growth-factor receptors. In animal studies, full-thickness hot-plate burns healed more quickly with aloe gel than with silver sulfadiazine or salicylic-acid cream, and aloe gel has helped prevent delayed hypersensitivity in UV-irritated skin and contact hypersensitivity. **Antioxidant activity.** Several compounds in aloe gel protect tissues against free-radical damage, both directly and by supporting the body's own systems; two aloe dihydroisocoumarins show free-radical-scavenging properties. Aloe gel extract has been shown to decrease lipid peroxidation and hydroperoxides in diabetic rats while increasing superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in the liver and kidney; after radiation exposure, aloe gel significantly reduced oxidative damage in liver, lung and kidney tissue in irradiated rats (Saada et al 2003). Three-year-old plants appear to hold the highest flavonoid and polysaccharide content — and the best free-radical-scavenging capacity — compared with two- and four-year-old plants. **Other actions.** Aloe is an immunostimulant and anti-inflammatory (the gel reduces oxidation of arachidonic acid). Aloe *latex* is a stimulant laxative (via anthraquinones), increasing intestinal water content, stimulating mucus secretion and inducing peristalsis. Aloe gel has been studied for anti-ulcer, cytoprotective and mucus-stimulatory effects, and as a possible liver- and kidney-protective agent in type-2 diabetes, where leaf gel decreased degenerative kidney changes and lowered serum urea and creatinine. Aloe also shows antimicrobial and antiviral activity and has been used for radiation-induced dermatitis and ulcers. **Cautions.** Aloe may interact with hypoglycaemic (blood-sugar) medications and laxatives. This writing is educational and reflects traditional use and published research — it is not medical advice, does not diagnose or treat any condition, and herbs can interact with medications. Please speak with your practitioner before use.