Aloe vera: benefits, dosage, contraindications

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Aloe vera is a pseudo‑cactus plant of the family Liliaceae that grows in hot, dry climates. It is a perennial shrub that can reach up to 1 meter in height, with green, fleshy, triangular leaves that are toothed at the edges. Aloe vera has been used for more than 4,000 years, notably as a treatment for burns or as a laxative. Aloe vera is composed of three layers: the outer layer, which protects and gives rigidity to the plant. Beneath this layer are two substances, the gel and the latex, which are used for medicinal purposes. Aloe gel is a clear, somewhat jelly‑like substance found in the inner part of the leaf, which has strong emollient properties (it softens and soothes tissues). Aloe latex, yellow in color, is found beneath the skin of the leaf; it contains 20% to 40% anthraquinones (mainly aloin), which have powerful laxative effects. Aloe vera has traditionally been used to aid digestion, to relieve external burns (topical use), and more recently for weight control.

Other name(s) 

aloe, aloes, Barbary aloe, aloes

Scientific name(s)

Aloe barbadensis, Aloe indica, Aloe africana

Family or group: 

Plants

Active ingredients:

Anthraquinones

Aloeride

Acemannan


Indications

Scoring methodology

EFSA approval.

Several randomized, double-blind, controlled clinical trials (> 2), including a significant number of patients (>100), with consistently positive conclusions for the indication.
Several randomized, double-blind, controlled clinical trials (> 2), including a significant number of patients (>100), with positive conclusions for the indication.
One or more randomized studies, or several cohorts or epidemiological studies, with positive conclusions for the indication.
Clinical studies exist but are uncontrolled, with conclusions that may be positive or conflicting.
No clinical studies to date that can demonstrate the indication.


Acne
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According to clinical research, a topical application morning and evening of a 50% aloe gel, combined with a topical application of a 0.025% tretinoin gel, in addition to daily cleansing, improves acne lesions by approximately 35% compared with tretinoin gel and cleansing alone.

Posologie

posologieOral: leaf

populationAdolescents

formulationgel


Constipation
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Aloe vera is used for occasional constipation in people aged over 12 years. nnThe hydroxyanthracene derivatives (DHA), responsible for the laxative effect, are the cause of multiple well-documented adverse effects. EFSA indicates that these DHA are also likely to damage DNA and to be carcinogenic. The available data did not allow EFSA to establish a daily dose for DHA without deleterious effects on health. nnMoreover, EMA specifies that the recommended daily dose in standardized herbal preparations in liquid or solid form is equivalent to 10 - 30 mg of hydroxyanthracene derivatives expressed as aloin.nnDuration of use should not exceed one week. If symptoms persist, consult a physician. nn

Posologie

posologieOral use: leaf

posologie10 - 30 mg

duration1 - weeks

populationAdolescents, Adults, Seniors

formulationstandardized preparation


Type 2 diabetes
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Most clinical research shows that oral intake of aloe vera can reduce fasting blood glucose and HbA1c (glycated hemoglobin) in adults with diabetes and in the pre-diabetes stage. An analysis of 92 patients shows that aloe vera is associated with a greater overall reduction in fasting blood glucose among patients whose fasting blood glucose level was greater than or equal to 200 mg/dL. Another analysis including 206 patients shows that aloe vera increases high-density lipoproteins (HDL) and reduces triglycerides, total cholesterol, and low-density lipoproteins (LDL) compared with placebo in pre-diabetic and untreated diabetic adults. The most effective dose and formulation of aloe for treating diabetes are not clear. Aloe vera gel powder, raw crushed aloe leaves, and aloe vera juice have been used for 4 to 14 weeks. Solid aloe formulations ranging from 100 to 1,000 mg per day have been used. Aloe juice ranging from 15 to 150 mL per day has been used.

Posologie

posologieOral: leaf

posologie15 - 150 mL

populationAdults

formulationconcentrated juice


Psoriasis
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The topical application of a 0.5% aloe extract cream three times a day for 4 weeks improves the resolution of psoriatic plaques compared with placebo. It appears to reduce scaling, erythema, and infiltration.

Posologie

posologieTopical: leaf

duration4 - weeks

populationAdults

formulationaloe extract cream


Obesity
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Clinical research suggests that taking a specific aloe gel complex containing 147 mg of treated aloe gel, administered twice daily for 8 weeks, reduces weight by 0.6 kg and fat mass by 1.0 kg compared with placebo in overweight or obese patients, diabetic or prediabetic.

Posologie

posologieOral: leaf

posologie294 mg

duration8 - weeks

populationAdults

formulationgel


Metabolic syndrome
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According to one study, a specific aloe gel complex may reduce body weight, fat mass index, and insulin resistance in prediabetic individuals or in early type 2 diabetes.

Posologie

posologieOral: leaf

posologie294 mg

duration8 - weeks

populationAdults

formulationgel


Dyslipidemia
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Studies suggest that taking aloe extract 10 - 20 mL/day orally for 12 weeks may reduce total cholesterol by about 15%, low-density lipoprotein (LDL) cholesterol by about 18%, and triglycerides by about 25% to 30% in patients with hyperlipidemia.

Posologie

posologieOral: leaf

posologie10 - 20 mL

duration12 - weeks

populationAdults

formulationconcentrated juice


Aphthous ulcers
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One study showed that applying an aloe vera gel three times a day for minor recurrent aphthous stomatitis was associated with an increased healing rate and decreased pain compared with placebo gel. Other clinical evidence suggests that using a dressing containing acemannan, a polysaccharide extracted from Aloe vera, reduces the average healing time of aphthous ulcers compared with an oral analgesic.

Posologie

posologieOral: leaf

formulationgel


Properties


Laxative

full-leaffull-leaffull-leaffull-leaf

The outer part of the Aloe vera leaf secretes a yellow-colored liquid (called latex, or sap) rich in hydroxyanthracene derivatives (HAD), molecules that have a very strong laxative effect. There are two different mechanisms of action: 1. Stimulation of colonic motility leading to an acceleration of intestinal transit. 2. Inhibition of the absorption of water and electrolytes (Na+, Cl-) by the epithelial cells of the colon and an increase in the secretion of water and electrolytes into the intestinal lumen.

Usages associés

Constipation

Dermatological effect

full-leaffull-leaffull-leafempty-leaf

It has been shown in vivo that aloe gel reduces ultraviolet-induced erythema and increases the water content of the stratum corneum. In addition, it increases skin elasticity and dermal collagen content, and reduces transepidermal water loss, thereby improving signs of skin fatigue. On the other hand, when applied to psoriatic plaques, aloe extract cream appears to reduce cellular scaling, erythema, and infiltration. This results in a reduction or resolution of the plaques.

Usages associés

Acne, Burns, Psoriasis, Canker sores

Wound healing

full-leaffull-leaffull-leafempty-leaf

Aloe gel may inhibit the synthesis of thromboxane A2, a potent vasoconstrictor, which helps improve microcirculation. This can accelerate the healing of burns and chilblains. The anti-inflammatory properties of topical aloe do not appear to interfere with healing, but they decrease wound tension, probably by stimulating fibroblasts and increasing collagen formation, which accelerates wound healing.

Usages associés

Burns, Canker sores

Anti-inflammatory

full-leaffull-leafempty-leafempty-leaf

In vitro, aloe gel has an anti-inflammatory effect by lowering levels of prostaglandin E2 and interleukin-8 in the colorectal mucosa. In addition, the carboxypeptidase and salicylate components of aloe gel have been shown to inhibit bradykinin (a hormone with a potent vasodilatory effect, involved in the mechanism of pain). Locally, salicylic acid and other anti-prostaglandin components contained in aloe may be responsible for aloe's local anti-inflammatory activity; this is likely related to an inhibitory effect on the arachidonic acid pathway via cyclooxygenase.

Usages associés

Acne, Burns

Hypoglycemic

full-leafempty-leafempty-leafempty-leaf

Animal studies suggest that aloe gel may have hypoglycemic effects. The possible mechanism of action is stimulation of beta cells (investigated in diabetic mice), leading to a decrease in blood glucose levels. However, the results of human studies in diabetic patients remain contradictory.

Usages associés

Type 2 diabetes, Metabolic syndrome

Antioxidant

full-leafempty-leafempty-leafempty-leaf

Studies in animal models have shown that the antioxidant effects of aloe pulp are due to aloe derivatives and the glycoproteins contained in aloe. These antioxidant effects may play a role in the anti-inflammatory and wound-healing effects of aloe.

Usages associés

Dyslipidemia, Obesity, Metabolic Syndrome


Safe dosage

Adults 12 years and older: 10 mg - 30 mg (standardized preparation)

Aloe vera is safe when used topically in the form of aloe gel.nnOrally, aloe gel can be used safely. It has been used safely at a dose of 15 ml per day for up to 42 days. nnHowever, aloe latex, used for constipation, contains hydroxyanthracene derivatives (HADs) which are responsible for numerous well-documented adverse effects. The EFSA indicates that these HADs are likely to damage DNA and to be carcinogenic and that the available data did not allow EFSA to establish a daily dose for HADs without adverse effects on health. nnFurthermore, the EMA specifies that the recommended daily dose in standardized herbal preparations in liquid or solid form is equivalent to 10 - 30 mg of hydroxyanthracene derivatives expressed as aloin, and this is for subjects over 12 years of age and should not exceed one week of treatment. nn


Interactions

Médicaments

Antiplatelet agents/Anticoagulants: moderate interaction

Aloe vera appears to inhibit thromboxane A2 and prostaglandins, and thus may reduce platelet aggregation. Theoretically, concomitant use of aloe and other antiplatelet drugs may reduce platelet aggregation and increase the risk of bleeding.

Antidiabetic drugs: moderate interaction

Clinical research suggests that aloe gel may lower blood glucose and increase the risk of hypoglycemia when used with antidiabetic drugs.

Digoxin: strong interaction

Theoretically, aloe latex increases the risk of adverse effects and the toxicity of cardiac glycoside medications due to potassium loss.

Diuretics: moderate interaction

Excessive use of aloe latex can worsen diuretic-induced potassium loss and increase the risk of hypokalemia.

Laxatives: moderate interaction

Because of the laxative effects of aloe latex, concomitant use with other laxatives may worsen water and electrolyte loss.


Precautions

Type 2 diabetes: use with caution

Research suggests that aloe gel has a hypoglycemic effect. Blood glucose should be monitored closely.nn


Contraindications

Pregnant women: contraindicated

Aloe vera is contraindicated in pregnant women because of the potentially mutagenic effect of the anthraquinones present in aloe leaf extracts and aloe latex.nn

Breastfeeding women: contraindicated

Aloe vera is contraindicated in breastfeeding women because anthraquinones present in the aloe leaf extract and latex can pass into breast milk.nn

Digestive disorders: contraindicated

Because of the irritating effect of anthranoids, aloe latex is contraindicated in people with acute intestinal inflammation (Crohn's disease, ulcerative colitis), ulcers, or those suffering from undiagnosed abdominal pain, nausea, or vomiting.nn

Renal insufficiency: contraindicated

Theoretically, oral intake of aloe latex may cause an electrolyte imbalance and worsen renal disorders.

Hemorrhoids: contraindicated

Aloe latex is contraindicated in hemorrhoids because of the risk of stenosis, thrombosis, and prolapse.