Aloe Vera: Clinical Use, Safety, Side Effects, and Interactions
History and Cultural Significance
Ancient Roots:
Aloe vera, with the scientific name Aloe barbadensis Miller, has a rich history dating back thousands of years.
The name “Aloe” is derived from the Arabic word “Alloeh,” meaning “shining bitter substance,” and “vera” in Latin means “true.”
Greek scientists considered Aloe vera a panacea around 2000 years ago, while Egyptians referred to it as “the plant of immortality.”
Historical Usage:
Throughout history, Aloe vera has been used for its health, beauty, medicinal, and skincare properties.
Ancient cultures, including Greece, Egypt, India, Mexico, Japan, and China, recognised and utilised Aloe vera for various purposes.
Ancient Egypt:
Aloe vera was highly valued in ancient Egypt, especially by queens like Nefertiti and Cleopatra. It was a crucial component of their beauty regimens, used to maintain youthful and radiant skin.
Historical records indicate that Aloe vera was part of the medicinal toolkit employed by physicians in ancient Egypt, who typically used Aloe vera to treat wounds and burns.
Ancient Greece:
Greek scientists recognised the medicinal properties of Aloe vera around 2000 years ago. It was considered a versatile remedy, with applications for both internal and external use.
Ancient China:
Aloe vera found a place in traditional Chinese medicine. It was believed to have healing properties and was utilised to address various health concerns.
India — Ayurvedic Practices:
Aloe vera has been part of Ayurvedic medicine in India for centuries. It was incorporated into formulations for its potential benefits in promoting skin health and addressing digestive issues.
Ancient Rome:
Historical accounts suggest that Aloe vera was used by military leaders like Alexander the Great and Christopher Columbus. It was applied to treat wounds sustained by soldiers, showcasing its efficacy in addressing skin injuries.
Medieval Europe:
Aloe vera continued to be valued during the Middle Ages in Europe. It was cultivated in monastic gardens and used for its healing properties.
These historical uses highlight the widespread recognition of Aloe vera across diverse cultures for its therapeutic applications. While ancient civilisations may not have had the scientific understanding we do today, their empirical observations laid the foundation for the continued use of Aloe vera in modern skincare and alternative medicine.
Modern Days:
In the early 1800s, Aloe vera was used as a laxative in the United States. However, a significant shift occurred in the mid-1930s when it proved effective in treating chronic and severe radiation dermatitis.
Botanical Features
Aloe vera belongs to the Asphodelaceae (Liliaceae) family and is a shrubby or arborescent, perennial, xerophytic succulent.
It thrives in dry regions of Africa, Asia, Europe, and America.
There are at least 420 different plant species of Aloe. Aloe vera specifically refers to the Aloe barbadensis Miller plant, which is the most common form used in Aloe-based products.
Characteristics:
The plant has triangular, fleshy leaves with serrated edges, yellow tubular flowers, and fruits with numerous seeds.
Each leaf consists of three layers: inner clear gel, middle layer of bitter latex, and outer protective rind.
The outer pulp of Aloe leaves, known as the latex, contains anthraquinones. Aloin is an anthraquinone found in the latex that may give the plant its laxative qualities.
Chemical Composition:
Medicinal species, such as Aloe vera, A. barbadensis (Barbados aloe), A. vulgaris, A.arborescens, A. ferox (Cape aloe), A. perryi (Socotrine or Zanzibar aloe), are for the most part native to South Africa, Madagascar and Arabia. The different species have somewhat different concentrations of active ingredients,
Active Components:
Aloe Barbadensis leaves contain over 200 nutritional substances, including:
Vitamins: A, B1, B2, B3, B5, B6, B12, C, E, choline, and folic acid.
Enzymes: alkaline phosphatase, amylase, bradykinase, carboxypeptidase, catalase, cellulase, lipase, and peroxidase.
Minerals: Calcium, chromium, copper, iron, selenium, magnesium, manganese, potassium, sodium, zinc.
Sugars: Monosaccharides (glucose, fructose) and polysaccharides (glucomannans).
Anthraquinones: Phenolic compounds traditionally known for their laxative effects.
Fatty Acids: Arachidonic acid, cholesterol, campesterol, β-sitosterol, lupeol.
Hormones: Auxins and gibberellins.
Chromones
Saponins
Salicylic acids
Lectins
Mechanisms of Action and Properties
Healing Properties: Stimulates fibroblast activity, increases collagen synthesis, and accelerates wound contraction.
UV and Gamma Radiation Protection: Exhibits a protective effect against radiation damage, reducing immunosuppressive cytokines.
Anti-inflammatory Action: Inhibits the cyclooxygenase pathway, reducing prostaglandin E2 production.
Immune System Effects: Modulates mast cell activity, stimulates interleukin production, and inhibits reactive oxygen free radicals.
Laxative Effects: Anthraquinones induce laxative effects by increasing intestinal water content and peristalsis.
Antiviral and Antitumor Activity: Acts on enveloped viruses and shows potential in cancer chemoprevention.
The antioxidant and/or anti-inflammatory properties of Aloe vera are explained by its content in vitamin A, C and E, in the glycoprotein C-glucosyl chromone, in certain sterols (campesterol, β-sitosterol and lupeol), vegetal hormones (auxins and giberrelins) and bradykinase. Campesterol, β-sitosterol, lupeol and two anthraquinones (aloin and emodin) act as analgesics and antiseptics. These sterols are also found in shea butter and sabal/saw palmetto (Serenoa repens)
Clinical Uses
Aloe vera has been used as folk medicine for a host of therapeutic indications of which the inner gel is the component extensively used and studied. Some uses of Aloe vera are based on scientific evidence from human and/or animal studies, while other uses are based on tradition.
Scientific-based therapies for Aloe vera include seborrheic dermatitis, psoriasis vulgaris, genital herpes, skin burns, wound healing, pressure ulcers, mucositis, radiation dermatitis, acne vulgaris, lichen planus, frostbite, aphthous stomatitis, type 2 diabetes mellitus, HIV infection, cancer prevention, ulcerative colitis and constipation.
Traditional-based therapies for Aloe vera include alopecia, bacterial and fungal skin infections, parasitic infections, chronic leg wounds, systemic lupus erythematosus, and arthritis. Although topical application for its anti-inflammatory effect may be delayed and minute, oral administration has shown a significant response. However, too high a dose has been linked with an initial inflammatory reaction. Favourable response to the gel has also been demonstrated to support the use of A. vera in wound-healing and as an antibacterial agent, although limited to simple, uncomplicated wounds.
“It is recommended that the fresh juice from the plant is used, and not the store-bought juice within other products or on its own. The reason for this is that the medicinal use of the plant diminishes with time, and there is much questioning about whether or not you can receive benefits from the store-bought aloe, even if the product has been filled with preservatives.”
Safety, Side Effects, and Interactions
Safety Considerations:
Topically, Aloe vera is generally safe but may cause redness, burning, or rare dermatitis.
Orally, it may lead to abdominal cramps, diarrhoea, and potential electrolyte imbalances with prolonged use.
Contraindications: Aloe vera is contraindicated in cases of known allergy to plants in the Liliaceae family. It is not recommended during pregnancy due to theoretical stimulation of uterine contractions.
Interactions: A. vera may increase the absorption of steroid creams and interact with medications like digoxin, digitoxin, furosemide, and oral hypoglycaemic drugs.
References:
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