Aloe vera is the mucilaginous substance obtained from the central parenchymatous tissues of the large blade-like leaves of Aloe vera. It should not be confused with aloes, which is obtained by evaporating water from the bitter yellow juice that is drained from the leaf.
Aloe vera contains polysaccharides, tannins, sterols, saponins, vitamins, minerals, cholesterol, gamma-linolenic acid and arachidonic acid. Unlike aloes, aloe vera does not contain anthraquinone compounds and does not therefore exert a laxative action.
Used externally, aloe vera acts as a moisturiser and reduces inflammation. Internally, it may act as an anti-inflammatory, hypoglycaemic and hyperlipidaemic agent. It also has anti-platelet activity.
Topical aloe vera has been investigated for its effects on wound healing and psoriasis, while oral aloe vera has been investigated in patients with diabetes mellitus and hyperlipidaemia.
A review in 1987 concluded that topical application of aloe vera gel reduces acute inflammation, promotes wound healing, reduces pain and exerts an antipruritic effect. A further review in 1999 stated that research had continued to confirm these benefits.
A double-blind, placebo-controlled study of 60 people with psoriasis of mean duration 8.5 years found that applying aloe vera to skin lesions three times a day for 8 months led to significant improvement in 83% of aloe vera patients but in only 6% of those who used placebo.
In rabbits, aloe vera cream was found to be better than placebo and as effective as oral pentoxifylline in improving tissue survival after frostbite.
In a study of 27 patients, aloe vera gel healed burns faster than Vaseline gauze,5 and in rats enhanced wound healing in second-degree burns.
However, a recent Cochrane review identified a single trial of aloe vera supplementation that suggested delayed wound healing with aloe vera, but the reviewers concluded that the results of the trial were not easily interpretable.
A recent systematic review of 10 studies8 showed that oral aloe vera might be useful as an adjunct for lowering blood glucose concentrations in diabetes and for reducing blood lipid levels in hyperlipidaemia.
There is some evidence that the antiinflammatory actions of aloe vera might have therapeutic potential in inflammatory bowel disease. An in vitro study found that aloe vera gel had a dose-dependent inhibitory effect on the production of reactive oxygen metabolites and eicosanoids in human colorectal mucosa.
A randomised controlled study in 44 patients with ulcerative colitis found that aloe vera gel 100 ml four times weekly produced a clinical response more often than placebo, reducing histological disease activity. The researchers recommended that further evaluation of aloe vera in inflammatory bowel disease is needed.
None established, although the potential hypoglycaemic effect means that it should be used with caution in patients with diabetes mellitus. Preliminary research in rats has suggested that aloe vera has a hypoglycaemic effect.
Pregnancy and breast-feeding
No problems have been reported, but there have not been sufficient studies to guarantee the safety of aloe vera in pregnancy and breastfeeding.
None reported apart from occasional allergic reactions. However, there are no long-term studies investigating the safety of aloe vera.
Aloe vera has antiplatelet activity and could theoretically interact with drugs with antiplatelet effects. A case study in one individual found a potential interaction between aloe vera and sevoflurane, in which the woman lost 5 L of blood during surgery.
Aloe vera is available in the form of creams, gels, tablets, capsules and juice. The International Aloe Science Council operates a voluntary approval scheme that gives an official seal (‘IASC – certified’) on products containing certified raw ingredients processed according to standard guidelines.
Used internally, there is no established dose. Product manufacturers suggest 1 / 2 to 3/ 4 cup of juice or 1 to 2 capsules three times a day. The juice in the product should ideally contain at least 98% aloe vera and no aloin.
Used externally, aloe vera should be applied liberally as needed. The product should contain at least 20% aloe vera.
A huge number of in vitro and animal studies have examined aloe vera over the past 30 years. However, there have been few studies in humans, and these have been poorly controlled.
Topical aloe vera may be helpful in psoriasis, but whether it is useful for wound healing is unclear. There is some – albeit limited – evidence that oral aloe vera may be useful for lowering blood glucose in diabetes, reducing blood lipids in hyperlipidaemia and it may have therapeutic potential in inflammatory bowel disease.
Dietary Supplements, Third Edition, by Pamela Mason, BSc, MSc, PhD, MRPharmS, published by Pharmaceutical Press, London, 2007.