Aloe Vera

Plant Part Used

Leaf gel; latex

Active Constituents

Aloins (barbaloin and isobarbaloin); anthraquinones and anthranoids; aglycones; polysaccharides (including acemannan); glycoproteins (including aloctin A); prostaglandins; fatty acids (including b-sitosterol, cholesterol, campesterol). (1)

This section is a list of chemical entities identified in this dietary supplement to possess pharmacological activity. This list does not imply that other, yet unidentified, constituents do not influence the pharmacological activity of this dietary supplement nor does it imply that any one constituent possesses greater influence on the overall pharmacological effect of this dietary supplement.

Introduction

Aloe, a genus with over 150 species, is mostly native to East and South Africa. Aloe is a succulent plant that has been used medicinally for centuries. Records of its use date back to 1750 BC. The plant has a variety of uses, including topical application for wounds, burns and rashes. Aloe can also be used internally as a laxative and cathartic. The mucilaginous gel from the aloe leaf is an effective wound healing agent and is now found in many commercial skin-care products, shampoos, and conditioners. (2) The bitter, yellow latex from the plant contains hydroxyanthracene derivatives, which act as bowel stimulants and are used commercially as laxatives.

Interactions and Depletions

Interactions

Dosage Info

Dosage Range

Leaf gel: Apply topically as needed to affected areas. Aloe vera gel may be taken internally at doses of 1-3 tablespoons, up to 3 times daily; recommended to use aloin and aloe-emodin free products if using internally.

Latex: 20-30mg hydroxyantracene derivatives daily.

Most Common Dosage

Leaf gel: Apply topically as needed to affected areas. Internally: 2 tablespoons, 3 times a day; recommended to use aloin and aloe-emodin free products if using internally.

Latex: 20mg hydroxyanthracene derivatives daily.

Standardization

[span class=doc]Standardization represents the complete body of information and controls that serve to enhance the batch to batch consistency of a botanical product, including but not limited to the presence of a marker compound at a defined level or within a defined range.[/span]

Leaf gel: If using internally, it is recommended to use aloin and aloe-emodin free products.

Latex: The most current available medical and scientific literature indicates that this dietary supplement should be 20-30mg hydroxyanthracene derivatives per dose of the latex, calculated as anhydrous aloin.

Uses

Frequently Reported Uses

  • Constipation
  • Psoriasis
  • Wound Healing Agent
  • Wound, Burn Healing
Other Reported Uses
  • Inflammation
  • Ulcers
  • Antibacterial
  • Antifungal
  • Anti-Inflammatory.
  • Blood Sugar Lowering Activity
  • Immunostimulating Effects
  • Anti-acne

 

Toxicities & Precautions

General

Aloe is reported safe in recommended dosages. But, based on pharmacology, long term use or higher than recommended dosages may cause fluid and electrolyte imbalances. (3)

As aloe is a laxative, products should not be taken long-term unless aloin and aloe-emodin free products are used.

If used in wound healing and wound has not improved in five to seven days, seek further medical attention.

Aloe vera does not cause adverse dermal toxicity. (45)

Side Effects

Discontinue topical use if rash or irritation develops. (4)

Pregnancy/ Breast Feeding

Do not use in pregnancy and lactation. (5)

Age Limitations

Do not use in children under 2 years of age unless recommended by a physician.

Pharmacology

Aloe vera leaf gel has been used for centuries as a topical wound healing agent for traumatic wounds (from mechanical, traumatic, or thermal injury, including contusions, abrasions, punctures, fractures, sunburn, burns, and frost bite), and chronic wounds (including pressure and diabetic ulcers). (6) In one study, it was observed that aloe increased the collagen content of granulation tissue as well as cross-linking as seen by increased aldehyde content and decreased acid solubility. (7) The type I/ type III collagen ratio of treated groups was lower than that of the untreated controls, indicating enhanced levels of type III collagen.

The influence of aloe on the glycosaminoglycan (GAG) components of the matrix in a healing wound has also been reported as a mechanism in wound healing. The early stage of wound healing is characterized by the deposit of a provisional matrix, followed by the formation of granulation tissue and synthesis of collagen and elastin. A recent study reported the influence of aloe vera on the content of GAG and its types in the granulation tissue of healing wounds. (8) The amount of ground substance synthesized was found to be higher in wounds treated with aloe vera gel, with the levels of reported glycohydrolases (hyaluronic acid and dermatan sulfate) being elevated, indicating increased turnover of the matrix.

Both topical and oral treatments with aloe vera were found to have a positive influence on the synthesis of GAGs and contribute to wound healing. Of interest is a recent case report that aloe vera may be useful in lichen planus, a disease that involves the skin and mucous membranes characterized by unique eruptions. (9) The cause of this disease is unknown, but has been linked to emotional stress, and has also been attributed to viral infections.

Aloe contains vitamins and minerals (including vitamin C, E, and zinc) reported to be beneficial in wound healing. (10) , (11) The effects of aloe on wound healing are mixed. Some studies reported positive results while others showed no benefit or potential worsening of the condition.(39),(40) In first and second degree burns, the healing process of burnt wound as well as post-skin grafting might be effective using aloe vera since it increases the rate of epithelialization when compared with conventional treatments. (42) In addition, aloe vera also shows evaporative cooling capacities due to its analgesic properties. (43)

Aloe vera has been reported for years to be effective in treating various types of burns. (12),(13) A recent study supported these findings, where aloe vera gel was reported to increase microcirculation to the burn area, causing vasodilation and increased post-capillary venular permeability. (14) Aloe may also provide benefit to the skin burns that result from radiation therapy. A study evaluated the prophylactic use of a mild soap compared to the use of aloe vera gel in addition to the soap. Lower cumulative doses of radiation showed no difference. In patients receiving higher cumulative radiation doses, skin changes were observed in three weeks in the soap only group compared to five weeks in the group who was both the soap and the aloe gel. (15) There has been a report of aloe hindering the wound healing process, causing a thickness of granulation tissue with a decreased amount of hair follicles as compared to 1% silver sulfadiazine cream. (16)

Aloe vera gel also reportedly aids in wound healing topically due its anti-inflammatory activity. (17) Aloe constituents with anti-inflammatory activity include: mannose-6-phosphate; (18),(19) the glycoproteins aloctin A and alprogen; (20),(21) a C-glucosyl chromone; (22) the anthraquinones; (23) and gibberellin. (24) Aloe vera gel taken orally helped reduce symptoms of patients with ulcerative colitis due to its anti-inflammatory effect. (25)

An isolated acetylated mannan (polysaccharide) found in the leaf parenchyma of aloe, termed acemannan, has been reported to improve immune function and be an effective antiviral agent. (26),(27) Enhancement of macrophage activity, T-cell function, and interferon production by the body was reported with use of this agent. Acemannan has been anecdotally reported to be a potential therapeutic agent in the treatment of HIV and herpes simplex type 1, yet supportive evidence is lacking at this time. (28) A study did report that acemannan, in addition to suboptimal noncytotoxic concentrations of AZT or acyclovir, did act synergistically to inhibit the replication of HIV-1 and herpes simplex virus type 1 (HSV-1). (29) An amorphous hydrogel dressing derived from the aloe plant containing acemannan is approved by the FDA for the management of stages I through IV pressure ulcers. (30)

Aloe vera leaf gel has also been reported useful in peptic ulcer disease (in animals). (31) The isolated constituent aloctin A given intravenously in laboratory animals inhibited the volume of gastric juice, acid, and pepsin output in pylorus-ligated rats, and significantly inhibited the development of Shay ulcers and indomethacin-induced gastric lesions in these animals. (32) The constituent aloe-emodin also was reported to inhibit the growth of H. pylori in vitro. (33)

Aloe also has antibacterial and antifungal constituents including lupeol, salicylic acid, urea nitrogen, cinnamic acid, phenol, and sulfur. (34) Aloe Vera fresh leaves showed significant antifungal activity based on fungicidal concentration against fungus growth of Botrytis gladiolorum, Fusarium oxysporum f.sp. gladioli, Heterosporium pruneti and Penicillium gladioli. (44)

Aloe has a reported hypoglycemic effect in laboratory animals and in one small clinical trial with human subjects. (35) The hypoglycemic effect of aloe and its bitter principle may be mediated through stimulating synthesis and/or release of insulin from the beta cells of the Islets of Langerhans. (36) A study in diabetic rats evaluated the effect of aloe vera leaf pulp extract and an aloe vera leaf gel extract. The pulp extract displayed a hypoglycemic effect, especially in the type 2 diabetic rats. Contrarily, the gel extract had a hyperglycemic effect in the type 2 diabetic rats. (37)

The usage of Aloe vera in topical application whereby by combining with Ocimum gratissimum oil, the enhancing effect by aloe vera on the anti-acne properties induces synergistic effect which is more effective than the drug 1% Clindamycin in the treatment of Acne Vulgaris. (41)

It has long been recognized that the latex from aloe is an anthranoid stimulant laxative. Studies have reported the effects of aloe as a laxative, with the 1,8-dihydroxyanthracene derivatives (aloe-emodin, aloins). (38)

References

  1. McCarthy TJ, et al. A comparative investigation of methods used to estimate aloin and related compounds in Aloes. Planta Med. Jan1970;18(1):36-43.
  2. Salcido R. Complementary and alternative medicine in wound healing. Adv Wound Care. Nov1999;12(9):438
  3. View Abstract: Ishii Y, et al. Studies of aloe. III. Mechanism of cathartic effect. (2). Chem Pharm Bull. Tokyo. Jan1990;38(1):197-200.
  4. View Abstract: Ernst E. Adverse effects of herbal drugs in dermatology. Br J Dermatol. Nov2000;143(5):923-9.
  5. View Abstract: Telefo PB, et al. Effects of an aqueous extract of Aloe buettneri, Justicia insularis, Hibiscus macranthus, Dicliptera verticillata on some physiological and biochemical parameters of reproduction in immature female rats. J Ethnopharmacol. Dec1998;63(3):193-200.
  6. Salcido R. Complementary and alternative medicine in wound healing. Adv Wound Care. Nov1999;12(9):438.
  7. View Abstract: Chithra P, et al. Influence of Aloe vera on collagen characteristics in healing dermal wounds in rats. Mol Cell Biochem. Apr1998;181(1-2):71-6.
  8. View Abstract: Chithra P, et al. Influence of Aloe vera on the glycosaminoglycans in the matrix of healing dermal wounds in rats. J Ethnopharmacol. Jan1998;59(3):179-86.
  9. View Abstract: Hayes SM. Lichen Planus--Report of Successful Treatment with Aloe Vera. Gen Dent. May1999;47(3):268-72.
  10. View Abstract: Andrews M, et al. The role of zinc in wound healing. Adv Wound Care. Apr1999;12(3):137-8.
  11. View Abstract: Wipke-Tevis DD, et al. Nutrition, tissue oxygenation, and healing of venous leg ulcers. J Vasc Nurs. Sep1998;16(3):48-56.
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  13. View Abstract: Rodriguez-Bigas M, et al. Comparative evaluation of aloe vera in the management of burn wounds in guinea pigs. Plast Reconstr Surg. Mar1988;81(3):386-9.
  14. View Abstract: Somboonwong J, et al. Therapeutic effects of Aloe vera on cutaneous microcirculation and wound healing in second degree burn model in rats. J Med Assoc Thai. Apr2000;83(4):417-25.
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  20. View Abstract: Saito H, et al. Pharmacological studies on a plant lectin aloctin A. II. Inhibitory effect of aloctin A on experimental models of inflammation in rats. Jpn J Pharmacol. Feb1982;32(1):139-42.
  21. View Abstract: Ro JY, et al. Inhibitory mechanism of aloe single component (alprogen) on mediator release in guinea pig lung mast cells activated with specific antigen-antibody reactions. J Pharmacol Exp Ther. Jan2000;292(1):114-21.
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  24. View Abstract: Davis RH, et al. Aloe vera and gibberellin. Anti-inflammatory activity in diabetes. J Am Podiatr Med Assoc. Jan1989;79(1):24-6.
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  35. View Abstract: Ghannam N, et al. The antidiabetic activity of aloes: preliminary clinical and experimental observations. Horm Res. 1986;24(4):288-94.
  36. View Abstract: Ajabnoor MA. Effect of aloes on blood glucose levels in normal and alloxan diabetic mice. J Ethnopharmacol. Feb1990;28(2):215-20.
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  38. View Abstract: Ishii Y, et al. Studies of aloe. III. Mechanism of cathartic effect. (2). Chem Pharm Bull. Tokyo. Jan1990;38(1):197-200.
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  40. Fulton, J.E. The stimulation of postdermabrasion wound healing with stabilised aloe vera gel-polyethylene oxide dressing. J Dermatol Surg Oncol. 1990; 16: 460-467
  41. L. O. Orafidiya, E. O. Agbani, A. O. Oyedele, O. O. Babalola, O. Onayemi, F. F. Aiyedun. The effect of aloe vera gel on the anti-acne properties of the essential oil of Ocimum gratissimum Linn leaf – a preliminary clinical investigation. International Journal of Aromatherapy. 2004;1(14):15-21
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