Aloe

What Is Aloe?

Aloe is a genus of succulents with sharp ridges on the leaves, and a thick, slippery gel on the inside. Aloes of all species have been used for a wide range of conditions, and is one of the longest recorded herbal medicines in human history. The use of aloe dates back to the early Egyptians, Chinese, and Roman empires. Alexander the Great has been said to have conquered the island of Socotra, off the coast of Africa in order to secure Aloe growing there to heal his soldiers.

Aloe has a wide range of clinical actions both internally and externally, and remains popular amongst herbalists and product developers for anything from skin conditions, digestive complaints, liver dysfunction, and cardiovascular disease.

How Is Aloe Used?

Aloe is commonly used as a topical agent for burns, skin irritations, and eczema. The thick mucilage contained in the leaf gel has antiseptic, anti-inflammatory, and vulnerary actions, making it an excellent choice for general skin irritations.

Internally, aloe provides similar support for the epithelial tissue of the digestive tract. Consumed internally also offers some mild laxative actions and hepatobiliary effects.

Traditional Uses

Western Herbal Medicine

Aloe vera (and other Aloes) have been used for a long time in various cultures, for its actions on conditions such as: anti-inflammatory, immunostimulant, antiseptic, wound and burn healing, anti-tumoral and laxative effects ^{5,6,7,8Reference 5Reynolds T · 1999ReviewAloe vera leaf gel: a review updateReference 6Heggers JP et al. · 1995AnimalWound healing effects of Aloe gel and other topical antibacterial agents in rat skinReference 7Chithra P et al. · 1998AnimalInfluence of Aloe vera on the healing of dermal wounds in diabetic ratsReference 8Dana et al. · 2012The effect of Aloe vera leaf gel on fatty streak formation in hypercholesterolemic rabbits}.

Traditional Chinese Medicine

Pinyin

Lu Hui

Taste

Bitter ^{13Reference 13Wu · 2005An illustrated Chinese materia medica}

Energy

Cold ^{13Reference 13Wu · 2005An illustrated Chinese materia medica}

Channels

Liver and large intestine ^{13Reference 13Wu · 2005An illustrated Chinese materia medica}

Action

Removes liver heat, improves intestinal motility ^{13Reference 13Wu · 2005An illustrated Chinese materia medica},

Indications

Constipation with restless insomnia due to heat accumulation ^{13Reference 13Wu · 2005An illustrated Chinese materia medica}

Cautions & Safety

Do not use during pregnancy or in patients with cold deficient spleen or stomach disorders ^{13Reference 13Wu · 2005An illustrated Chinese materia medica}.

Ayurvedic Medicine

In the Ayurvedic and Thai medicine, Aloe was used to treat peptic ulcers, burns, wounds, abscesses, mouth ulcers, and inflammation ^{12Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patient}.

Botanical Information

Aloe is a flowering succulent plant found growing in the tropics and subtropics.

Aloe is a member of the Asphodelaceae family of plants. This family is home to over 40 genera, and about 900 different species, 500 of which are comprised of the Aloe genus.

Harvesting, Collection & Preparation

Leaf extracts containing quantified levels of the chemical acemannan are recommended (no less than 11.25 mg/ml) ^{12Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patient}.

Aloe extracts containing low anthraquinones (through removal process) are also preferred for internal use ^{12Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patient}.

Pharmacology & Medical Research

Atherosclerosis

Aloe vera’s confirmed anti-inflammatory actions ^{4Reference 4Davis RH et al. · 1989Wound healing}, as well as its hypocholesterolemic actions ^{8Reference 8Dana et al. · 2012The effect of Aloe vera leaf gel on fatty streak formation in hypercholesterolemic rabbits}, may be the main mechanism of actions in its suggested ability to treat and prevent atherosclerosis. Inflammation has been linked closely with the development of atherosclerosis ^{1,2Reference 1Haddad et al. · 2013Clinical trialAloe vera for prevention of radiation-induced dermatitis: a self-controlled clinical trial.Current Oncology, 20(4), 345. doi:10.3747/co.20.1356View study →Reference 2Vogler BK · 1999Systematic reviewAloe vera: a systematic review of its clinical effectiveness}, and using anti-inflammatory medications such as Aloe vera may soon become a mainstay of treating or preventing this ultimately deadly disease process.

Dermatitis

The emollient actions of Aloe vera has been well studied and is an effective treatment in radiation-induced dermatitis ^{1Reference 1Haddad et al. · 2013Clinical trialAloe vera for prevention of radiation-induced dermatitis: a self-controlled clinical trial.Current Oncology, 20(4), 345. doi:10.3747/co.20.1356View study →}.

In burns, a topical application of Aloe gel is suggested to inhibit thromboxane B2 and prostaglandin F-2-alpha formation. This subsequently preserves dermal circulation and improves the outcome of both first degree, and 2nd-degree burns ^{12Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patient}.

Inflammation

Aloe vera has well-documented actions as an anti-inflammatory ^{4,12Reference 4Davis RH et al. · 1989Wound healingReference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patient}. The anti-inflammatory action is reported to rely on the presence of anthraquinones ^{12Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patient}.

Cholesterol

Aloe vera was shown to reduce the atherosclerosis formation significantly, and blood cholesterol levels of animals fed a high cholesterol diet vs. those with just a high cholesterol diet ^{8Reference 8Dana et al. · 2012The effect of Aloe vera leaf gel on fatty streak formation in hypercholesterolemic rabbits}. This common disease process is one of the major risk factors for developing chronic heart disease, or myocardial infarction, and stroke.

Antiviral

Anthraquinones extracted from Aloe barbadensis was found to inhibit the adsorption of some enveloped viruses into cells. Thus it was able to prevent the viruses from replicating. The mechanism of action was found to be through an interaction with the viral envelope. ^{11Reference 11Sydiskis et al. · 1991Inactivation of enveloped viruses by anthraquinones extracted from plantsView study →}.

It was reported to possess activity against viruses such as HIV ^{12Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patient},

Phytochemistry

Aloe yields two chemically distinct products from one leaf: the bitter yellow latex just under the rind, and the clear inner-leaf gel. Its medicinal activity is usually attributed to two groups — the anthraquinones of the latex and the polysaccharides of the gel ^{1,12,14Reference 1Haddad et al. · 2013Clinical trialAloe vera for prevention of radiation-induced dermatitis: a self-controlled clinical trial.Current Oncology, 20(4), 345. doi:10.3747/co.20.1356View study →Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patientReference 14Hamman · 2008Composition and applications of Aloe vera leaf gelView study →}.

The latex anthraquinones — chiefly aloin (the major one, present as a mix of aloin A and B) and the related anthraquinone glycosides, with aloe-emodin formed on oxidation — are the stimulant-laxative and antiviral principles ^{11,12Reference 11Sydiskis et al. · 1991Inactivation of enveloped viruses by anthraquinones extracted from plantsView study →Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patient}. The gel is roughly 98–99% water; of its small solid fraction, the dominant polysaccharide is acemannan, an acetylated mannan that makes up the majority of gel solids and carries much of the immunomodulating and wound-healing activity. It is the marker compound most leaf extracts are standardised to, often to no less than 11.25 mg/mL ^{12,14,15Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patientReference 14Hamman · 2008Composition and applications of Aloe vera leaf gelView study →Reference 15Liu et al. · 2019ReviewExtraction, purification, structural characteristics, biological activities and pharmacological applications of acemannan, a polysaccharide from Aloe vera: A reviewView study →}.

Beyond these the leaf supplies saponins, sterols, lignins and salicylic acid, along with vitamins, minerals, enzymes, sugars and amino acids ^{1,12,14Reference 1Haddad et al. · 2013Clinical trialAloe vera for prevention of radiation-induced dermatitis: a self-controlled clinical trial.Current Oncology, 20(4), 345. doi:10.3747/co.20.1356View study →Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patientReference 14Hamman · 2008Composition and applications of Aloe vera leaf gelView study →}.

Constituent Summary

Figures describe whole leaf or the fraction noted; the gel is ~98–99% water, so gel-solid percentages are of the small dried residue, not of fresh gel. Anthraquinone content of “low-anthraquinone” internal-use extracts is deliberately reduced, and all values vary widely with species, plant age and processing ^{1,12,14Reference 1Haddad et al. · 2013Clinical trialAloe vera for prevention of radiation-induced dermatitis: a self-controlled clinical trial.Current Oncology, 20(4), 345. doi:10.3747/co.20.1356View study →Reference 12Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patientReference 14Hamman · 2008Composition and applications of Aloe vera leaf gelView study →}.

Clinical Applications

Aloe is a useful laxative, hepatoprotective, and for reducing triglyceride and cholesterol levels. Externally it’s very useful for treating all kinds of skin irritations, burns, and traumatic damage.

Cautions & Safety

Do not use aloe internally for long periods of time.

References

1. Haddad, P., Amouzgar-Hashemi, F., Samsami, S., Chinichian, S., & Oghabian, M. (2013). Aloe vera for prevention of radiation-induced dermatitis: a self-controlled clinical trial.Current Oncology, 20(4), 345. doi:10.3747/co.20.1356
2. Vogler BK, Ernst E (1999). Aloe vera: a systematic review of its clinical effectiveness. Br J Gen Pract. 49:823-8.
3. Natural Products Insider. (2009). International Aloe Science Council presents a scientific primer on aloe. www.naturalproducts insider.com/ebooks/2009/10/iasc-presents-a-scientific-primer-on-aloe. aspx
4. Davis RH, Leitner MG, Russo JM, Byrne ME. (1989). Wound healing. Oral and topical activity of Aloe vera. J Am Podiatr Med Assoc. 79(11):559–62.
5. Reynolds T, Dweck AC. (1999). Aloe vera leaf gel: a review update. J Ethnopharmacol. 68(1-3):3–37.
6. Heggers JP, Kucukcelebi A, Listengarten D, Broemel KF. (1995). Wound healing effects of Aloe gel and other topical antibacterial agents in rat skin. Phytotherapy Res. 9(6):455–7.
7. Chithra P, Sajithlal GB, Chandrakasan G. (1998). Influence of Aloe vera on the healing of dermal wounds in diabetic rats. J Ethnopharmacol. 59(3):195– 201.
8. Dana, N., Javanmard, S. H., Asgary, S., Asnaashari, H., & Abdian, N. (2012). The effect of Aloe vera leaf gel on fatty streak formation in hypercholesterolemic rabbits. J Res Med Sci, 17(5), 439-442.
9. Libby P, Ridker PM. (2004). Inflammation and atherosclerosis: role of C-reactive protein in risk assessment. Am J Med. 2004;116(Suppl 6A):9S–16S.
10. Hansson GK, Libby P. (2006). The immune response in atherosclerosis: a double-edged sword. Nat Rev Immunol. 2006;6(7):508–19.
11. Sydiskis, R. J., Owen, D. G., Lohr, J. L., Rosler, K. H., & Blomster, R. N. (1991). Inactivation of enveloped viruses by anthraquinones extracted from plants. Antimicrobial Agents and Chemotherapy, 35(12), 2463-2466. doi:10.1128/aac.35.12.2463
12. Bone, K. (2003). A clinical guide to blending liquid herbs: Herbal formulations for the individual patient. Edinburgh [u.a.: Churchill Livingstone. (Pg. 61-64).
13. Wu, J. N. (2005). An illustrated Chinese materia medica. New York: Oxford University Press. (Pg 62-63).
14. Hamman, J. H. (2008). Composition and applications of Aloe vera leaf gel. Molecules, 13(8), 1599-1616. doi:10.3390/molecules13081599
15. Liu, C., Cui, Y., Pi, F., Cheng, Y., Guo, Y., & Qian, H. (2019). Extraction, purification, structural characteristics, biological activities and pharmacological applications of acemannan, a polysaccharide from Aloe vera: A review. Molecules, 24(8), 1554. doi:10.3390/molecules24081554