Suppression

Aloe vera (Chinese Aloe, Indian Aloe, True Aloe, Barbados Aloe, Burn Aloe, First Aid Plant)

Category: Medicines - plant based

Type

Voluntary

Introduction and description

 

Aloe vera  is a succulent plant species, widely cultivated for use in the cosmetics industry and in herbal medicine. According to Mrs Grieve some species of Aloe were also once used in dyeing “A beautiful violet colour is afforded by the leaves of the Socotrine Aloe, and it does not require a mordant to fix it.

 The species has a number of synonyms: A. barbadensis Mill., Aloe indica Royle, Aloe perfoliata L. var. vera and A. vulgaris Lam.  Common names include Chinese Aloe, Indian Aloe, True Aloe, Barbados Aloe, Burn Aloe,and  First Aid Plant.

The species epithet vera means "true" or "genuine". The species was first described by Carl Linnaeus in 1753 as Aloe perfoliata var. vera, and was described again in 1768 by Nicolaas Laurens Burman as Aloe vera in Flora Indica on 6 April and by Philip Miller as Aloe barbadensis some ten days after Burman in the Gardener's Dictionary.

The plant has gained the Royal Horticultural Society's Award of Garden Merit.

Distribution

The natural range of A. vera is unclear, as the species has been widely cultivated throughout the world. Naturalised stands of the species occur in the southern half of the Arabian Peninsula, through North Africa (Morocco, Mauritania, Egypt), as well as Sudan and neighbouring countries, along with the Canary, Cape Verde, and Madeira Islands. 

The species was introduced to China and various parts of southern Europe in the 17th century. The species is widely naturalised elsewhere, occurring in temperate and tropical regions of Australia, Barbados, Belize, Nigeria, Paraguay, Mexico and the US states of Florida, Arizona and Texas.

Large-scale agricultural production of Aloe vera is undertaken in Australia, Bangladesh, Cuba, the Dominican Republic, China, Mexico, India, Jamaica, Kenya, Tanzania and South Africa, along with the USA.

Description

About Aloes

The Aloes in general are succulent plants belonging to the Lily family, with perennial, strong and fibrous roots and numerous, persistent, fleshy leaves, proceeding from the upper part of the root, narrow, tapering, thick and fleshy, usually beset at the edges with spiney teeth. Many of the species are woody and branching. In the remote districts of S.W. Africa and in Natal, Aloes have been discovered 30 to 60 feet in height, with stems as much as 10 feet in circumference.

a Japanese variety of Aloe

The succulent leaves and stem of Aloes in general protect the plants against drought.  The cuticle which covers every part of the plant is, in those which contain a great quantity of pulpy material, formed so as to preserve and suck in moisture very easily and to evaporate it very slowly. If the leaf of an Aloe is separated from the parent plant, it can be laid in the sun for several weeks without becoming entirely shrivelled; and even when considerably dried by long exposure to heat, it will, if plunged into water, become plump and fresh again after a few hours.

Aloe vera

Aloe Vera itself is a stemless or very short-stemmed succulent plant growing to 60–100 cm (24–39 in) tall, spreading by offsets. The leaves are thick and fleshy, green to grey-green, with some varieties showing white flecks on their upper and lower stem surfaces. The margin of the leaf is serrated and has small white teeth.

The flowers are produced in summer on a spike up to 90 cm (35 in) tall, each flower being pendulous, with a yellow tubular corolla 2–3 cm (0.8–1.2 in) long.  There is no calyx, the corolla is tubular, divided into six narrow segments at the mouth. The capsules contain numerous angular seeds.

 Like other Aloe species, Aloe vera forms ‘arbuscular mycorrhiza’, a symbiosis that allows the plant better access to mineral nutrients in soil.

Aloes and Agaves

The true Aloe is in flower during the greater part of the year and is not to be confused with another plant, the Agave or American Aloe (Agave Americana), which is remarkable for the long interval between its periods of flowering.

Various species of Agave, all of which closely resemble each other, have been largely grown as ornamental plants since the first half of the sixteenth century in the south of Europe, and are completely acclimatized in Spain, Portugal and Southern Italy, but though often popularly called Aloes all of them are plants of the New World whereas the true Aloes are natives of the Old World. From a chemical point of view there is also no similarity at all between Aloes and Agaves.

Cultivation

Wikipedia

Aloe vera has been widely grown as an ornamental plant….. [Its] succulence enables the species to survive in areas of low natural rainfall, making it ideal for rockeries and other low water-use gardens.

 

The species is hardy in zones 8–11, although it is intolerant of very heavy frost or snow. The species is relatively resistant to most insect pests, though spider mites, mealy bugs, scale insects, and aphid species may cause a decline in plant health. In pots, the species requires well-drained, sandy potting soil and bright, sunny conditions; however, Aloe plants can burn under too much sun or shrivel when the pot does not drain water. Terra cotta pots are preferable as they are porous.

Potted plants should be allowed to completely dry prior to rewatering. When potted, aloes become crowded with "pups" growing from the sides of the "mother plant", they should be divided and repotted to allow room for further growth and help prevent pest infestations. During winter, Aloe vera may become dormant, during which little moisture is required. In areas that receive frost or snow, the species is best kept indoors or in heated glasshouses.

History

The medicinal value of Aloes has been known for thousands of years.  Aloes were employed by the ancients and were known to the Greeks as a production of the island of Socotra as early as the fourth century B.C. The drug was used by Celsus, as well as by the later Greek and Arabian physicians, though it is not mentioned either by Hippocrates or Theophrastus.  Aloe vera’s use also appears in the Ebers Papyrus from the 16th century BC, in Dioscorides' De Materia Medica and Pliny the Elder's Natural History - both written in the mid-first century AD. It is also written of in the Juliana Anicia Codex of 512 AD.

It is also mentioned in the Anglo-Saxon leech-books.  There is a reference to it as one of the drugs recommended to Alfred the Great by the Patriarch of Jerusalem.  From this we can infer that its use was not unknown in Britain as early as the tenth century. At this period the drug was imported into Europe by way of the Red Sea and Alexandria. In the early part of the seventeenth century, there was a direct trade in Aloes between England and Socotra, and in the records of the East Indian Company there are notices of the drug being bought off the King of Socotra, the produce being a monopoly of the Sultan of the island.

Mrs Grieve
The Mahometans, especially those in Egypt, regard the Aloe as a religious symbol, and the Mussulman who has made a pilgrimage to the shrine of the Prophet is entitled to hang the Aloe over his doorway. The Mahometans also believe that this holy symbol protects a householder from any malign influence.
In Cairo, the Jews also adopt the practice of hanging up the Aloe.
In the neighbourhood of Mecca, at the extremity of every grave, on a spot facing the epitaph, Burckhardt found planted a low shrubby species of Aloe whose Arabic name, saber, signifies patience. This plant is evergreen and requires very little water. Its name refers to the waiting-time between the burial and the resurrection morning.

Medicinal uses

Mrs Grieve
The fleshy leaves of the true Aloe contain near the epidermis or outer skin, a row of fibrovascular bundles, the cells of which are much enlarged and filled with a yellow juice which exudes when the leaf is cut. When it is desired to collect the juice, the leaves are cut off close to the stem and so placed that the juice is drained off into tubs. This juice thus collected is concentrated either by spontaneous evaporation, or more generally by boiling until it becomes of the consistency of thick honey. On cooling, it is then poured into gourds, boxes, or other convenient receptacles, and solidifies.
Aloes require two or three years' standing before they yield their juice. In the West Indian Aloe plantations they are set out in rows like cabbages and cutting takes place in March or April, but in Africa the drug is collected from the wild plants.

The conflict of old and new uses

 

The uses to which Aloe vera is now being put do not seem to tie in with its ancient uses.  Aloe vera as a medicine was at one time used as an anti-parasitic and purgative, however there appears to be little mention of this in the literature now.

This is all the more alarming when one realises that Aloe vera gel is used commercially as an ingredient in yogurts, beverages, and some desserts.  So those people with IBS who think that yoghurt may help and who then imbibe a commercial yoghurt with the gel in may be in for a bit of a shock.  The same is true for aloe latex, which was taken orally for conditions ranging from glaucoma to multiple sclerosis until the FDA required manufacturers to discontinue its use.

There is no mention of any benefits to those with eye problems in the old medicinal literature and the only reason one could make that claim is due to the presence of BETA-CAROTENE, a natural chemical that is found in numerous perfectly safe cheap foods.

Aloe vera as anti-viral, anti-parasitic and anti-fungal

Many of the uses that Dr Duke’s analysis has identified point to its anti-parasitic properties when taken internally, and may point to quite useful anti-viral activity.  Its anti-cancer properties, for example, may be partly mediated by its anti-viral activity. 

All the following chemicals in the plant are anti-virals ALOE-EMODIN , ALOIN , ASCORBIC-ACID 1-5 g/day [Vitamin C] , BETA-SITOSTEROL , EMODIN ED50=1.1 ug/ml , LAURIC-ACID , LIGNIN , LUPEOL , POLYPHENOLS , RHEIN EC50=1.1 , STIGMASTEROL, ACEMANNAN .  Aloe vera has some chemicals that help with the herpes virus – and very little of this is mentioned in the herbal medicine community - ALOE-EMODIN , ALOIN , ASCORBIC-ACID 1-5 g/day, LYSINE 0.5-3 g/day , THIAMIN , ACEMANNAN 1 g/day – so Vitamin C again and the Vitamin thiamine, but also some very specific chemicals like Aloe-emodin.

The natural chemical in Aloe vera - LUPEOL [IC50=46.8 ug/ml] is anti-malarial.  The two natural chemicals - ASCORBIC-ACID [Vitamin C again], but also ACEMANNAN 1 g/day are antimeasles.  ACEMANNAN is also antiretrovirus.

Candidiasis is a nasty fungal infection and Aloe vera has natural chemicals that are Candidicides – including ALOE-EMODIN MIC=25-250 ug/ml , CHRYSOPHANOL , LAURIC-ACID and RHEIN .  Furthermore there appears to be more general anti-fungal activity via ALOE-EMODIN, CHRYSOPHANIC-ACID , CINNAMIC-ACID , CONIFERYL-ALCOHOL, COUMARIN, P-COUMARIC-ACID, RHEIN , SELENIUM and ACEMANNAN

Aloe vera as chelator

There are also natural chemicals in Aloe vera that act as chelators - LIGNIN and POLYPHENOLS.

Aloe vera as purgative

If you look at Mrs Grieve and Dr Duke’s analysis, both mention its purgative properties.  Dr Duke calls the action ‘cathartic’ and specifies the following chemicals - ALOE-EMODIN, CHRYSOPHANOL, EMODIN , RHEIN , CHRYSAZIN.

A purgative is a violent laxative, if we can put it this way, it purges you of everything and may not be very helpful in the long run, as it may purge all the good bacteria from your intestines.  As such there is a risk associated with taking this unless you are totally infested with worms and parasites and completely constipated. 

Wikipedia
Aloin, a compound found in the exudate of some Aloe species, was the common ingredient in over-the-counter (OTC) laxative products in the United States until 2002 when the Food and Drug Administration banned it because the companies manufacturing it failed to provide the necessary safety data. Aloe vera has potential toxicity, with side effects occurring at some dose levels both when ingested or applied topically. Although toxicity may be less when aloin is removed by processing, Aloe vera that contains aloin in excess amounts may induce side effects.

Aloe vera and Agave – the source of the confusion?

an agave

Why are the uses to which modern alternative medicine communities put the plant so different to those to which the ancients put it?  The answer may be the problem of the Agave and the Aloe.

In Ayurvedic medicine the Aloe is called kathalai, BUT SO ARE extracts from Agave.  In other words there is a lot of room for errors to be made here as Agave has a completely different medicinal profile to Aloe Vera. 

Are all these historical mentions really of Aloe vera or are they of Agave? 

If we take one well known variety of Agave - Agave sisalana (Agavaceae) also known as Mescal; Hemp Plant; Sisal; Sisal Agave; and Sisal Hemp.  It contains chemicals like SARSAPOGENIN that are antipsoriac – they help the skin; together with chemical such as BETA-SITOSTEROL , CHLOROGENIN, DIOSGENIN  and GITOGENIN that are anti-inflammatories.  In other words historical references to the plant’s help in soothing skin conditions may actually be referring to the Agave not the Aloe.

The wild claims of the herbal medicine industry

The so called ‘herbal medicine industry’ is just an extension of the pharmaceutical industry.  It is largely unregulated, and it has made some very wild claims about Aloe vera.  One claim, for example, is about skin conditions.

 

This is not to say that Aloe vera does not have chemicals that help with skin conditions.  For example, it has antiezcemic activity via ARACHIDONIC-ACID, ASCORBIC-ACID 3.5-5 g/day, LINOLEIC-ACID and ZINC 150 mg/day.  In other words Vitamin C, LA and Zinc – which you can get by eating a lemon!  There is not anything uniquely special in this area.

The rather wild claims made by some herbal medicine companies that Aloe vera is anti multiple sclerosis are not unfounded but they are achieved by two widely available nutrients - LINOLEIC-ACID and MAGNESIUM available in many foods.  I don’t think the herbal medicine companies are being deliberately wicked, but on the other hand they are being ignorant.  Many wild claims made for Aloe vera are much the same.  It ‘cures rheumatoid arthritis’, no it doesn’t – it contains two widely available nutrients - ASCORBIC-ACID 1 g 2x/day [vitamin C] and SELENIUM – which help with arthritis.  Again you are better off eating lemons and oranges.

The claims for wound healing may also be exaggerated, but there is antisepic activity via a number of chemicals - ALOE-EMODIN MIC=2-64 ug/ml , ASCORBIC-ACID MIC=3.3-217 mg/ml , CHRYSOPHANOL , EMODIN , FORMIC-ACID , P-COUMARIC-ACID , RHEIN and ZINC 50 mg/day .

There are also some hints that some of the chemicals are good antibacterial agents - ALOE-EMODIN MIC=2-64 ug/ml, for example is Antistaphylococcic.

But Aloe vera is a medicine not a food and this promotion of a plant that has toxic chemicals in it - ANTHRAQUINONES and FORMIC-ACID is frankly irresponsible.

Before people go into a blind panic over the Aloe vera used topically [externally] via facial tissues or in makeup, moisturizers, soaps, sunscreens, incense, shaving cream, or shampoos, the likelihood of it actually doing harm externally appears small.  Nevertheless, the risk is there.  And there are very specific guidelines to which the manufacturer's should be taking heed:-

In Aloe-derived ingredients used in cosmetics, regardless of species, anthraquinone levels should not exceed 50 ppm.  PMID:  17613130

Oral ingestion of aloe vera, however, is, shall we say ‘ill advised’ unless it has been processed to remove the harmful chemicals and is being used specifically to help with  illnesses for which better and safer alternatives - such as food - are unavailable.

 

References and further reading

Int J Toxicol. 2007;26 Suppl 2:1-50. Final report on the safety assessment of AloeAndongensis Extract, Aloe Andongensis Leaf Juice,aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice,aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract.   Cosmetic Ingredient Review Expert Panel1.  1Cosmetic Ingredient Review, Washington DC 20036, USA

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