Aloe - Herbal Monograph Series

Written By Dr. Colleen Huber

Aloe leaves and in bloom in the spring. Blossoms may also be yellow or white.

Aloe vera and Aloe spicata species, gel inside leaves

Uses

  • Top treatment for burns, including sunburn, from other heat sources and from radiation, as well as frostbite

  • Demulcent (soothing) for gastrointestinal distress and gastric lesions

  • Cathartic laxative (latex)

  • Multiple in-vitro anti-cancer effects

 

For burns

A meta-analysis found that burn patients using topical Aloe vera on burned skin healed an average of nine days faster than no applied dressing or with silver sulfadiazine, for first- and second- and third-degree burns, with improved healing in the Aloe group over control groups. ¹ ²

Aloe is also the first choice of prevention and treatment of the burns that cancer patients experience from radiation treatments that may target a tumor affecting an internal organ, but by way of an inevitable route through the skin. That area of skin is then vulnerable to burn injury.

At Nature Works Best Medical Clinic, both topical aloe and hyperbaric oxygen treatments are first line treatments for acute burns, and should be started immediately or as soon as possible after injury.

 

For gastritis and ulcers

Dyspepsia was one indication in the 1895 American Dispensatory for medicinal use of Aloe.³ Aloe was found to be effective for both prevention and treatment of alcohol-induced gastritis and ulcers.⁴

 

For inflamed skin wounds, blisters, burns, gum infections

Ancient Greek physician Dioscorides wrote of Aloe’s effect in healing internal and external wounds.  He prescribed it with a spoonful of water to stop the spitting of blood, “as well as the gums and all sores in the mouth.”  He used Aloe as a styptic for various skin wounds and hemorrhoids.⁵

For wounds, aloe vera gel was found superior to all competing substances tested in wound closure rate, leaving a negligible scar by Day 28.⁶

Wound recovery in a controlled clinical trial showed that 68% of aloe patients’ frostbite wounds recovered completely, but only 33% of controls’ frostbite wounds did.⁷

 

For constipation

The 1926 U.S. Dispensatory describes Aloe as follows:  “In chronic constipation, . . . especially when dependent on an atonic condition of the lower bowel, it is one of the most useful laxatives that we possess.”⁸

 

Pharmacology and Mechanisms of Action

The abundant gel in Aloe leaves holds polysaccharides, especially mannans in matrix, Recent research credits those compounds as mainly responsible for healing burns in an ideal semi-solid physical structure adjacent to skin.  There is both physical and chemical benefit to this thick natural wound dressing with high water content that happens to contain phytochemical compounds in just such a matrix to allow fibroblast migration and collagen formation, to enable healing.   These compounds attract fibroblasts to the area, stimulating the synthesis of collagen.⁹ ¹⁰   Nature Works Best Clinic formulates vitamin C with Aloe and / or Calendula, for their topical antimicrobial properties (against microbes including MRSA, Pseudomonas and E. coli) and wound-healing properties for skin repair.

Magnesium lactate is an important constituent of Aloe gel¹¹ and is likely responsible for relieving burning and itching due to the Mg Lactate effect of inhibiting histidine decarboxylase.¹² This in turn prevents the production of histamine.  As a result the redness, swelling and severe itching that result from burns and other skin injuries is alleviated.

Aloe gel stimulates and strengthens epithelial cells of the gastrointestinal lining, healing and giving relief of the symptoms of gastritis and ulcers.  The size and number of alcohol-induced gastric lesions were reduced. This was found to be due to Aloe’s reduction of activity of matrix metalloproteinase-9 (MMP-9).¹x<sup>3</sup>

Other constituents include mannose 6-phosphate, acemannan and aloegenin.  Mannose 6-phosphate’s role in wound-healing is that it binds growth factor receptors on fibroblasts to form collagen and proteoglycans, which promotes tissue repair.¹⁴ Acemannan and aloegenin have also shown wound-healing activity, in contributing to granulation, macrophage cytokine production and as repair to skin injuries following radiation exposure.¹⁵ ¹⁶ Acemannan and aloe polysaccharides were found to be especially healing for the GI tract.¹⁷ Also aloe supports several glycosaminoglycan components of the extracellular matrix and hyaluronic acid.  This increases wound granulation and collagen crosslinking.¹⁸

Part of Aloe’s benefit in wound healing is how it prevents ongoing tissue damage from burns, frostbite and other injuries.  It does this by inhibiting thromboxane A2.  Thromboxane A2 is a double-edged sword for repair from a wound; it is associated with progressive tissue damage following trauma to the skin.   That is, it causes vasoconstriction and clotting, which limits blood loss from a wound, but that same mechanism suffocates and dries up healing mechanisms from the bloodstream to the wound,¹⁹ which if left unchecked contributes to tissue damage.   Aloe inhibits thromboxane A2, and is therefore applied after blood loss has been controlled.  

There are several anti-inflammatory effects of aloe vera.  The constituent aloin lowers inflammatory cytokines, such as TNFα, IL-1β and IL-6, which in turn lower NF-κB, thereby calming inflammation.  Aloin does this by inhibiting the release of those pro-inflammatory cytokines, and by inhibiting release of reactive oxygen species (free radicals) and it does all of that in a dose-dependent way.²⁰ This shows increased benefit with increased use.

Aloe may also shows several anti-cancer effects.  When studying the effect of aloe emodin on nasopharyngeal carcinoma, it was found that aloe emodin suppressed phosphorylation of a gene, STAT3, which in turn had the effect of inhibiting cell proliferation and motility.²¹ Aloe emodin also, through the p38 and ERK MAPK signaling pathways, inhibited angiogenesis as well as invasion and metastasis.²² Taken together, this makes aloe useful in several important anti-cancer effects.

The cathartic effect of Aloe latex against constipation is attributed to anthraquinones, including 1,8-dihydroxy-anthracene, also known as Aloe-emodin, which stimulates propulsive contractions.  β-glycosides arrive intact to the colon where they are degraded by bacterial enzymes to Aloe-emodin anthrones, which have laxative effect. 

 

Side Effects and Contraindications

Aloe should not be taken internally by pregnant women or “to females liable to sudden uterine evacuations.”²³ Some of this caution is due to confusion between the clear to yellowish transparent gel, which makes up the bulk of the leaf volume, as opposed to the white latex substance surrounding the gel, on the inside surface of the leaf.  

Caution is also warranted in breastfeeding, due to the strong laxative effect.²⁴

The white latex is highly cathartic for both bowels and uterus, and so it must be strictly avoided in pregnancy.  The latex taken internally would also be contraindicated in irritable bowel syndrome, Crohn’s and ulcerative colitis.

Cathartics must be used only with the caution of possible dehydration or electrolyte imbalance, from sudden loss or upheaval of water and electrolytes during bowel catharsis.

The gel is perfectly safe to apply to the skin for anyone, and is rarely reported to be irritating, but for most people, in most uses, it is described as cooling and soothing to the skin.  Watch out for the spines along the edges of the leaf when splaying the leaf open to remove the gel. 

 

Native Origin and Range

Aloe species are evergreen perennial succulents in the Liliaceae family, similar to agaves.  Aloe plants store so much liquid that they may be seen hanging upside down for months from the ceilings of markets in Latin America, and then planted and regrowing, as this author has experienced.  So it survives for long times even after being uprooted.

Aloe’s healing power was recorded on a Sumerian clay tablet dating from 2200 B.C.  Then in Egypt, the Ebers Papyrus, written around 1552 B.C., described Aloe’s medicinal uses.²⁵ Aloe was cultivated at the time of Alexander the Great, in the fourth century B.C.²⁶ Dioscorides wrote about medicinal use of Aloe in the first century A.D.²⁷ He noted its growth through India, Arabia and Asia, although it is considered to be of African origin, from the south and west of Africa.  Over 300 species of Aloe grow throughout the world,²⁸ from sea level up to 7,000 feet altitude.   It is resistant to drought and has survived floods.

Dr. Colleen Huber
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