Aloe Leaves – The Self Preparation of Aloe Gel at Home is Risky

Due to the presence of anthranoids in aloe vera leaves, the self-preparation of aloe vera gel requires great care.

Dr. Christiane Lerch, Michaela Barthmann and Inge Gronbach


Currently whole aloe leaves are on offer in shops. According to the labeling, these leaves are from the species “aloe vera barbadensis miller”. The gel-like inner parts of the leaves are intended for consumption. According to instructions attached to the product, the outer green parts of the leaves should be completely removed, due to their bitter taste and laxative effects. In order to obtain the gel from the inside, the leaf should be cut into strips, the gel removed and, before consumption, rinsed with water. The daily consumption of 100 g gel is re­commended.
A trial conducted at CVUA Stuttgart shows that, despite the proper carrying out of the instructions, when one conducts this procedure under normal household conditions there is a risk that high amounts of toxicologically dangerous substances from the so-called „anthranoid“ class (anthraquinones) in the outer leaves can end up in the gel.


Illustration 1: Aloe vera (Photo: sarangib/Pixabay, CC0 Public Domain).

Illustration 1: Aloe vera (Photo: sarangib/Pixabay, CC0 Public Domain)


The inner leaf gel of aloe vera barbadensis miller has been traditionally eaten for many years. The industrially produced pure leaf gel is available under the names “Aloe Vera Juice“, “Aloe Vera Gel“, or “Aloe Vera Drink“, and is also offered in preparations with other foods.


The aloe vera plant contains so-called “anthranoids“. Anthranoids (syn.: anthraquinones) such as aloin A and aloin B are plant substances that, in addition to being present in aloe leaves, are also in senna leaves and medicinal rhubarb roots, among others [1].


Illustration 2: Chemical formula of 1,8-Dihydroxyanthrone.

Illustration 2: 1.8-Dihydroxyanthrone – the common basic structure of anthranoids [1]


These bitter tasting substances are concentrated in the upper layer of the aloe leaf. A yellow secretion that is emitted from the latex layer under the green rind of the leaf contains especially high amounts of aloin [2], [3a,b,c].


Illustration 3: Cross-section of an aloe leaf.

Illustration 3: Cross-section of an aloe leaf


Anthranoids such as aloin have strong laxative effects. Moreover, there is reason to suspect that this class of substances is carcinogenic. Their presence in food is therefore unwanted.

For medicinal drugs that contain anthranoids, strict indication limitations as well as in-pharmacy sales only, were established in 1999. The duration of usage was also reduced to a short period of time.

In 2013 a two-year program of the National Institute of Health (NIH) in the USA showed clear evidence of a cancerous effect from whole leaf extracts of Aloe Vera in rats [3a,b,c].

Whole leaf extract of Aloe Vera has been categorized by the International Agency for Research on Cancer of the WHO (IARC) as follows: [4]:

“Whole leaf extract of Aloe Vera is possibly carcinogenic to humans.“
For this reason, with the industrial manufacturing of Aloe Vera leaf gel, the aloin-containing leaf surface is separated very carefully and the gel may be further treated technologically, to remove the anthranoids [5].


The amount of aloin detected in aloe vera gel and aloe vera juice samples analyzed in Baden-Württemberg over the last few years was less than 0.1 mg/kg.


CVUA Stuttgart analyzed a sample whole Aloe Vera leaf taken from the market, testing the total amount of aloin contained therein. The amount of aloin ending up in the leaf cuttings as a result of the preparations was investigated, using utensils that are traditionally available in the home (knife, dishes, sieve, etc.) as well as typical household methods.

The test cuttings were taken from the middle, thick section of the leaf sample, in accordance with the attached instructions. The aloin content in the peeled and rinsed leaf gel amounted to 31 mg/kg. The taste of the gel was consistently bitter. The separated, unrinsed leaf gel contained 52 mg/kg aloin. When the green rind of the leaf was not peeled (see photo), the quantity of aloin in the leaf cutting was 520 mg/kg.


Illustration 4: Cut-off of leaves according to preparation instructions.

Illustration 4: Cut-off of leaves according to preparation instructions


The self-prepared gel, rinsed with water, contained 31 mg aloin per kg, about 300 times higher than the aloin content in the samples of industrially fabricated products.

The quantity of anthranoid in Aloe Vera leaves varies greatly. This depends on, e.g. which part of the leaf is used, as well as climate and cultivation conditions of the plant [2]. For self-made gel, the way in which the leaf is processed plays an important role.


Given these circumstances, it is difficult to calculate the quantity of aloin in Aloe Vera gel that has been self-prepared.


The results from the investigation carried out at CVUA Stuttgart illustrate that, when the Aloe Vera leaf is cut, the aloin that is present in the outer layer spreads over the cut surface and into the gel. The method of rinsing the gel with water at home would not and could not suffice for the removal of this aloin.

Based on our test with rinsed and unrinsed gels, adherence to the daily recommended consumption of 100 g Aloe Vera would mean exposure to 3.1 mg, respectively 5.2 mg of aloin. A strong laxative effect is to be expected with the consumption of 20 mg to 30 mg of aloin [6].

The 52 mg of aloin contained in 100 g of an unpeeled, cut leaf shows, however, that the careless, partial separation of the upper leaf layer can result in a significantly higher amount of aloin getting into the gel.

For anthranoid containing drugs the Federal Institute for Drugs and Medical Devices (BfArM) recommends not exceeding the daily intake of 30 mg of these substances and not taking the preparation for longer than one to two weeks [6].

In a current report (April 2017) of the consumer safety group Stiftung Warentest, the use of such medication is not advisable, due to its „relatively drastic effect“ [7].

Info Box – Consumer Tip

The self-preparation of Aloe Vera gel from whole leaves requires particular care, due to the anthranoids such as aloin contained therein.
An experiment conducted at CVUA Stuttgart shows that, even when the instructions are correctly carried out, parts of the aloin-rich latex layers can get into the ready-to-eat gel. This can lead to the intake of considerable amounts of aloin.

Due to the carcinogenic potential of anthranoids and their laxative effects, CVUA Stuttgart does not recommend making Aloe Vera gel oneself, but rather purchasing industrial products.



[1] (21.4.2017)

[2] Growth, soluble carbohydrates, and aloin concentration of Aloe vera plants exposed to three irradiance levels. A. Paez et al., Environmental and Experimental Botany 44 (2000), 133–139

[3a] NTP-Program Aloe Vera (Zusammenfassung); Headquartered at the National Institute of Environmental Health Science NIH-HHS, June 2016

[3b] National Toxicology Program – technical report: Aloe Vera; (21.4.2017)

[3c] Clear Evidence and Carcinogenic activity by a Whole-Leaf Extract of Aloe barbadensis (Aloe vera) in F344/N-Rats. M.D. Boudreau et. al., Toxicological Sciences 131 (1) 26–39 (2013)

[4] ) (21.4.2017)

[5] Processing of Aloe Vera Leaf Gel: A Review; C.T. Ramachandra et al., Am. J. Agril. & Biol. Sci., 3 (2); 502:510, 2008

[6] Bundesinstitut für Risikobewertung (BfR), Beurteilung der Verwendung von ganzen Blättern von Aloe arborescens und ihren Zubereitungen in Nahrungsergänzungsmitteln (Juni 2014)

[7] (21.4.2017)


Translator: Catherine Leiblein



Artikel erstmals erschienen am 01.06.2017