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Aloe Vera

James Odell, OMD, ND, L.Ac.


Aloe vera is a member of the Liliaceae (lily) family (or Asphodelaceae, Asparagales in APG system). According to the World Checklist of Selected Plant Families, there are currently about 580 species of Aloe. The genus is native to tropical and southern Africa, Madagascar, Jordan, the Arabian Peninsula, and various islands in the Indian Ocean (Mauritius, Réunion, Comoros, etc.). Aloe is a shrubby or arborescent, perennial, xerophytic, succulent, pea-green color plant found throughout the tropics and warmer regions worldwide. Because of this global naturalization, its true origin is unknown. The commercially significant aloes are perennials, with 15 to 30 fleshy leaves up to 1.5 feet long and 4 inches across the base. Saw-teeth mark the margins of the leaves.1


History

The Aloe vera plant has been known and used for centuries for its health, beauty, medicinal, and skincare properties. The name aloe vera derives from the Arabic word “Alloeh” meaning “shining bitter substance,” while “vera” in Latin means “true.” Belonging to the lily family and related to the onion, garlic, and asparagus, evidence supporting the early use of aloe was discovered on a Mesopotamian clay tablet dating from 2100 BC. 2000 years ago, Greek scholars regarded aloe as the universal panacea. The Egyptians called aloe “the plant of immortality.” Egyptian queens Nefertiti and Cleopatra used it as part of their regular beauty regimes.2


Today, Egyptians still hang an aloe plant over the door of a new house to provide a long and fruitful life for its occupants. According to the Roman scholar, Pliny, the plant was also used for embalming. In the first century C.E., the Greek physician Dioscorides used aloe for soothing sores and wounds. In the 10th century, aloe was used in England, and during the 17th-century records show that the East India Company frequently purchased aloe from the king of Socotra. Alexander the Great used it to treat soldiers’ wounds. One of the first references to aloe vera in English was a translation by John Goodyew in A.D. 1655 of Dioscorides’ Medical treatise De Materia Medica. By the early 1800s, aloe vera was in use as a laxative in the United States, but in the mid-1930s, a turning point occurred when it was successfully used to treat chronic and severe radiation dermatitis. Today, the aloe plant has a multi-purpose use, primarily in dermatology for burns and skin health, but also as a nutritious food and laxative.3


Chemical Properties

The plant produces two substances used for medicine: a gel that is obtained from the cells in the center of the leaf, and the latex, which is obtained from the cells just beneath the leaf’s skin. Aloe contains at least 75 known potentially active constituents: vitamins, enzymes, minerals, sugars, lignin, saponins, salicylic acids, and amino acids.4, 5, 6, 7


  • Vitamins: Aloe contains many vitamins such as A (beta-carotene), C and E, which are also antioxidants, and the B vitamins B1 (thiamine), B2 (riboflavin), B3 (niacin), B12 (cobalamins), choline, and B9 (folic acid).8

  • Enzymes: It contains 8 enzymes: aliiase, alkaline phosphatase, amylase, bradykinase, carboxypeptidase, catalase, cellulase, lipase, and peroxidase. Biochemical catalysts, such as amylase and lipase, can aid digestion by breaking down fats and sugars. Carboxypeptidase inactivates bradykinins and produces an anti-inflammatory effect. During the inflammatory process, bradykinin produces pain associated with vasodilation and, therefore, its hydrolysis reduces these two components and produces an analgesic effect.9, 10

  • Minerals: Aloe contains magnesium, calcium, chromium, copper, selenium, manganese, potassium, sodium, and zinc. These minerals are essential for the proper functioning of numerous critical enzyme systems in different metabolic pathways, and a few are antioxidants. Aloe juice contains high levels of magnesium, which is a vital nutrient for nerve and muscle use. Magnesium helps your body with more than 300 different enzyme reactions, including those that regulate your blood pressure. It also helps regulate heart rhythm. Magnesium also inhibits histidine decarboxylase and prevents the formation of histamine from the amino acid, histidine. Histamine is released in many allergic reactions and causes intense itching and pain. The prevention of its formation may explain the antipruritic or anti-itch effect of aloe. Zinc is also an important component in this beneficial plant — making it a great natural source for combating zinc deficiency.

  • Fatty acids: Aloe provides 4 plant steroids; cholesterol, campesterol, β-Sitosterol, and lupeol. All these have anti-inflammatory action and lupeol also possesses antiseptic and analgesic properties.

  • Sugars: Aloe contains monosaccharides (glucose and fructose) and polysaccharides: (glucomannans/polymannose). Sugars are derived from the mucilage layer of the plant under the rind, surrounding the inner parenchyma or gel. They form 25 percent of the solid fraction and comprise both mono- and polysaccharides. The most important are the long-chain polysaccharides, comprising glucose and mannose, known as glucomannans. The polysaccharides are absorbed complete and appear in the bloodstream unchanged hence they act as immunomodulators.11, 12, 13, 14, 15, 16

  • Hormones: Aloe contains auxins and gibberellins that help in wound healing and have an anti-inflammatory action.

  • Anthraquinones: The bitter aloes consist of free anthraquinones and their derivatives - barbaloin, aloe-emodin-9-anthrone, isobarbaloin, anthrone-C-glycosides, and chromones. In large amounts, these compounds exert a powerful laxative effect, but when smaller they appear to aid absorption from the gut, are potent antimicrobial agents and possess powerful analgesic effects.17, 18 They also reduce the formation of melanin and any tendency to hyperpigmentation.19, 20 Lignin with their penetrative ability to carry other active ingredients deep into the skin to nourish the dermis. Aloin and emodin act as analgesics, antibacterials, and antivirals.

  • Other medicinal components: Aloe also contains 20 of the 22-human required amino acids and 7 of the 8 essential amino acids. It also contains salicylic acid that possesses anti-inflammatory and antibacterial property. Lignin, an inert substance, when included in topical preparations, enhances the penetrative effect of the other ingredients into the skin. Saponins that are soapy substances form about 3% of the gel and have cleansing and antiseptic properties.

Mechanism of Actions

  • Healing properties: Glucomannan, a mannose-rich polysaccharide, and gibberellin, a growth hormone, interacts with growth factor receptors on the fibroblast, thereby stimulating its activity and proliferation, which in turn significantly increases collagen synthesis after topical application and oral consumption of aloe.21, 22 Aloe gel not only increased collagen content of the wound but also changed collagen composition (more type III) and increased the degree of collagen cross-linking. Due to this, it accelerated wound contraction and increased the breaking strength of resulting scar tissue.23, 24, 25 An increased synthesis of hyaluronic acid and dermatan sulfate in the granulation tissue of a healing wound following oral or topical treatment has also been reported.

  • Effects on skin exposure to UV and gamma radiation: Aloe gel has been shown to have a protective effect against radiation and sun damage to the skin.26, 27, 28, 29, 30 The exact mechanism is not yet known, but following the administration of aloe gel, an antioxidant protein, metallothionein, is generated in the skin, which scavenges hydroxyl radicals and prevents suppression of superoxide dismutase and glutathione peroxidase in the skin. It reduces the production and release of skin keratinocyte-derived immunosuppressive cytokines such as interleukin-10 (IL-10), and hence prevents UV-induced suppression of delayed-type hypersensitivity.31

  • Anti-inflammatory action: Aloe inhibits inflammation and adjuvant-induced arthritis primarily because it inhibits the cyclooxygenase pathway and reduces prostaglandin E2 production from arachidonic acid.32 Recently, the novel anti-inflammatory compound called C-glucosyl chromone was isolated from gel extracts.33

  • Effects on the immune system: Aloe polysaccharides enhance immunity activity and exert antioxidant effects.34 In a study on mice that had previously been implanted with murine sarcoma cells, acemannan stimulates the synthesis and release of interleukin-1 (IL-1) and tumor necrosis factor from macrophages in mice, which in turn initiated an immune attack that resulted in necrosis and regression of the cancerous cells.35 Several low-molecular-weight compounds are also capable of inhibiting the release of reactive oxygen free radicals from activated human neutrophils. Alprogen inhibits calcium influx into mast cells, thereby inhibiting the antigen-antibody-mediated release of histamine and leukotriene from mast cells.36, 37, 38

  • Laxative effects: The anthraquinones contained in the plant are a potent laxative. They increase intestinal water content, stimulates mucus secretion, and increases intestinal peristalsis.39

  • Antitumor effects: The anticancer, anti-tumor activity of aloe are primarily due to its immunomodulating and apoptotic death action on cancerous cells. This is largely promoted by a tumor cell-specific drug uptake process (e.g., aloe-emodin and barbaloin).40

Data suggest that constituents of aloe, such as acemannan, aloeride, and di(2-ethylhexyl) phthalate (DEHP) have immunomodulating and anticancer effects. In studies, a polysaccharide fraction has been shown to inhibit the binding of benzopyrene to primary rat hepatocytes, thereby preventing the formation of potentially cancer-initiating benzopyrene-DNA adducts. In another study Emodin from aloe inhibited cell proliferation and induced apoptosis in human liver cancer cell lines through p53- and p21-dependent pathways.41 An induction of glutathione S-transferase and an inhibition of the tumor-promoting effects of phorbol myristic acetate has also been reported which suggests a possible benefit of using aloe gel in cancer chemoprevention. 42, 43

  • Skin moisturizing and anti-aging effect: Its mucopolysaccharides help in binding moisture into the skin. Aloe stimulates fibroblast which produces collagen and elastin fibers making the skin more elastic and less wrinkled. It also has cohesive effects on the superficial flaking epidermal cells by sticking them together, which softens the skin. The amino acids also soften hardened skin cells and zinc acts as an astringent to tighten pores. Its moisturizing effects have also been studied in the treatment of dry skin associated with occupational exposure where aloe vera gel gloves improved the skin integrity, decreases the appearance of fine wrinkles, and decreases erythema.44 It is effective for sunburns and has an anti-acne effect.

  • Antiseptic effect: Aloe contains 6 antiseptic agents: Lupeol, salicylic acid, urea nitrogen, cinnamomic acid, phenols, and sulfur. They all have an inhibitory action on fungi, bacteria, and viruses.

  • Antiviral activity: Aloe has been shown to have anti-viral effects.45 These actions may be due to indirect or direct effects. The indirect effect is due to stimulation of the immune system and the direct effect is due to anthraquinones. The anthraquinone aloin inactivates various enveloped viruses such as herpes simplex, varicella zoster, and influenza.46

Contraindication: Contraindicated in cases of known allergy to plants in the Liliaceae family.


Pregnancy and breastfeeding: Oral aloe is generally not recommended during pregnancy due to theoretical stimulation of uterine contractions, and in breastfeeding mothers, it may sometimes cause gastrointestinal distress in the nursing infant.


Commercial production

The use of aloe gel and preparations containing it has become widespread and consequently, a large industry has developed. Thailand is one of the largest producers of aloe accounting for around a third of the total global production. Other leading producers include Mexico, Dominican Republic, South Africa, United States (Texas, Florida, California), and Costa Rica. Because the demand for aloe is increasing throughout the globe, growth rates in emerging markets such as India, China, and the Middle East are expected to expand. Numerous companies support a wide range of research activities and supply products in the form of the gel either in the raw form, concentrated or freeze or spray dried.


Aloe Vera Farm

Sources

Aloe products, including aloe gel, juice, capsules, extracts and cosmetics, can be found in many grocery and health food stores. Be sure to choose a product that is made by a reputable company to ensure that the extraction and processing methods do not reduce the plant’s beneficial properties. It turns out, after extracting the gel, heating it, and using fillers to make aloe vera products, the health benefits are minimized.

To stop the common misrepresentations in the industry, and the false idea that all aloe vera products produce the same benefits, the International Aloe Science Council developed a certification program that validates the quality and quantity of aloe vera in approved commercial products. When looking to purchase aloe, read the labels carefully and look for this important certification.

Conclusion

Aloe vera is truly a panacea plant. It is highly nutritious, containing many nutrients and health-benefiting phytochemicals. It is used for wound healing, to treat burns, psoriasis, frostbite, ulcerative colitis, diabetes, and to relieve constipation. Aloe exhibits both antioxidant and anti-inflammatory properties and acts against various microorganisms. It is easy to incorporate into a diet through the oral consumption of aloe juice. Aloe not only has numerous health-giving benefits but makes an attractive house plant. If burnt, a leaf may be cut from the plant and applied to the burn for instant healing relief.


References

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  13. Acemannan, a prominent glucomannan has also been found. Recently, a glycoprotein with antiallergic properties, called alprogen and novel anti-inflammatory compound, C-glucosyl chromone, has been isolated from Aloe vera gel.

  14. Ro, Jai Youl, Byung Chul Lee, Ji Young Kim, Yean Jun Chung, Myung Hee Chung, Seung Kee Lee, Tae Hyung Jo, Kyung Hwan Kim, and Young In Park. "Inhibitory mechanism of aloe single component (Alprogen) on mediator release in guinea pig lung mast cells activated with specific antigen-antibody reactions." Journal of Pharmacology and experimental therapeutics 292, no. 1 (2000): 114-121.

  15. Hutter, John A., Mohammad Salman, William B. Stavinoha, Neera Satsangi, Robert F. Williams, Robert T. Streeper, and Susan T. Weintraub. "Anti-inflammatory C-glucosyl chromone from Aloe barbadensis." Journal of natural products 59, no. 5 (1996): 541-543.

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  35. Ro, Jai Youl, Byung Chul Lee, Ji Young Kim, Yean Jun Chung, Myung Hee Chung, Seung Kee Lee, Tae Hyung Jo, Kyung Hwan Kim, and Young In Park. "Inhibitory mechanism of aloe single component (Alprogen) on mediator release in guinea pig lung mast cells activated with specific antigen-antibody reactions." Journal of Pharmacology and experimental therapeutics 292, no. 1 (2000): 114-121.

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  40. Kuo, Po-Lin, Ta-Chen Lin, and Chun-Ching Lin. "The antiproliferative activity of aloe-emodin is through p53-dependent and p21-dependent apoptotic pathway in human hepatoma cell lines." Life sciences 71, no. 16 (2002): 1879-1892

  41. Kim, Hyung Sik, and Byung Mu Lee. "Inhibition of benzo [a] pyrene-DNA adduct formation by Aloe barbadensis Miller." Carcinogenesis 18, no. 4 (1997): 771-776.

  42. Kim, Hyung Sik, Sam Kacew, and Byung Mu Lee. "In vitro chemopreventive effects of plant polysaccharides (Aloe barbadensis Miller, Lentinus edodes, Ganoderma lucidum and Coriolus versicolor)." Carcinogenesis 20, no. 8 (1999): 1637-1640.

  43. West, Dennis P., and Ya Fen Zhu. "Evaluation of aloe vera gel gloves in the treatment of dry skin associated with occupational exposure." American Journal of Infection Control 31, no. 1 (2003): 40-42.

  44. Zandi, Keivan, M. Abbas Zadeh, Kohzad Sartavi, and Zahra Rastian. "Antiviral activity of Aloe vera against herpes simplex virus type 2: An in vitro study." African Journal of Biotechnology 6, no. 15 (2007).

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