Almost everybody is familiar with the use of aloe for soothing sunburns, but much less known is the internal use of aloe. The active substances in aloe are thought to be the immunomodulatory gel polysaccharides (especially the acetylated mannans) and also glycoproteins. There should be a differentiation between the mucilaginous gel that is used from the parenchymatous cells that is used for a number of curative purposes, and the bitter yellow exudate that is from the bundle sheath cells, which is mainly used for its purgative properties (Grindlay and Reynolds, 1986). Among the topical uses of aloe are for skin irritations, to prevent irritation or skin injury from radiation, for mouth ulcers, for herpes, frostbite minimization, and periodontal use (Rieger and Carson, 2002; McCauley et al., 1990). Among the internal uses of aloe are for diabetes/blood sugar control, for mouth and stomach ulcers, lowering of cholesterol, for immune system support, inflammatory bowel disease and as a laxative (Borrelli and Izzo, 2000; Reynolds and Dweck, 1999).
Even though the scientific support behind aloe has not caught up to its popularity in usage, this will probably not stop people from using it, as it tends to be a favorite for topical use. The internal use of aloe will take time for people to become educated on how to use aloe correctly, and whether or not it is effective through clinical research.
Blood Sugar Regulation, Diabetes, and Wound Healing
A systematic review of aloe vera published research was conducted on the clinical data to assess its clinical effectiveness. Only controlled trials were included in the review, and all indications were included. Ten studies were found, and they indicated that oral administration of aloe could be beneficial for reducing blood lipid levels in patients with hyperlipidaemia. Topical administration was found not to be an effective preventative for radiation-induced injuries. However, topical administration might be effective for genital herpes and psoriasis, but it was unclear if aloe vera promoted wound healing. The authors cautioned that the results of the trials were very preliminary, and still needed clinical work to define the parameters and effectiveness of treatments (Vogler and Ernst, 1999).
Skin irritations and Burns
A systematic review of complimentary and alternative published literature was conducted to provide a brief overview on CAM medicine use and on two conditions, atopic dermatitis and chronic venous insufficiency and two treatment modalities, aloe vera gel and tea tree oil. For neither the aloe vera gel nor the tea tree oil did the authors conclude there to be compelling evidence of effectiveness (Ernst et al., 2002).
A prospective, randomized, blinded clinical trial was conducted to ascertain whether aloe vera might be helpful to decrease the skin reactions to radiation therapy. Patients were dived into two groups and randomized and either used aloe vera plus a mild detergent, or just the mild detergent alone. A protective effect for adding aloe to the treatment regimen was only found at the high dosing levles (>2,700 cGy), and only over time (Olsen et al., 2001).
In an open, uncontrolled, clinical study to investigate the efficacy of a bioadhesive patch (aloe vera hydrogel- Aloex patch) for aphthous stomatitis (mouth ulcers), 31 patients were administered at least 3 patches daily for 4 days. The study resulted in large improvements from the treatment with the patches in symptomology and pain, and the compliance was also markedly high (Andriani et al., 2000).
Two phase III studies were conducted to ascertain if aloe vera gel could be helpful for preventing radiation therapy-induced dermatitis. The first was a randomized, double-blind, placebo-controlled (with a placebo gel) study involving 194 women that were receiving breast or chest wall irradiation. The second was a placebo-controlled randomized study involving 108 patients with the aloe vs. no treatment. Aloe vera gel was not found to protect against radiation-induced dermatitis in either of the studies (Williams et al., 1996).
Syed et al. (1996) studied the efficacy of aloe vera extract 0.5% in a hydrophilic cream for its effectiveness in treating psoriasis vulgaris. The sixty patients with slight to moderate chronic plaque-type psoriasis and PASI (Psoriasis Area and Severity Index) scores between 4.8 and 16.7 were randomized into two parallel groups to received either 100 g tube of aloe or placebo. The patients were told to self-administer the cream topically at home for 3 times daily for 5 consecutive days per week (for a maximum of 4 weeks treatment). Treatment was well tolerated, and there were no adverse effects reported. The aloe vera extract 0.5% in the hydrophilic cream was statistically more effective than the placebo in curing the psoriasis lesion and lowering the PASI score.
Visuthikosol et al. (1995) compared the effectiveness in healing burn wounds with aloe vera gel compared to vaseline gauze. Aloe vera gel healed the burn wounds statistically faster than the vaseline gauze, with a healing time of 11.89 days for the aloe treatment vs. 18.19 days for the vaseline. In the histological examination of the healing it revealed that there was earlier epithelialization in the aloe group.
Immunity and Cancer
Lissoni et al (1998) studied the immunomodulating effect of aloe vera when used along with pineal indole melatonin (MLT) in pateints with advanced solid tumors for which no effective standard anticancer techniques are available. The 50 participants were given either MLT alone (20 mg/day orally in the dark period) or MLT plus aloe vera tincture (1 ml two times daily). The percent 1-year survival rate was higher in the aloe treatment group versus the MLT alone group, and stable disease was achieved in this group in a higher portion of the people. The authors concluded that MLT plus aloe vera extracts may produce therapeutic benefits, including stabilization of disease and survival, in patients with advanced solid tumors.
Safety / Dosage
The dosage of aloe depends on the preparation and the usage, of which there are many. Generally, as a laxative, aloe is used in the range of 50-200 mg daily or about 1-3 ounces orally. For topical applications the gel is generally applied throughout the day as needed.
No significant side effects of aloe vera gel have been noted, except the occasional allergy. One study found anthranoid laxative abuse (such as aloe vera gel) to be linked to colorectal cancer (Siegers et al., 1993).
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EDITOR'S NOTE: This monograph can be found in The Health Professional's Guide to Dietary Supplements (Lippincott, Williams & Wilkins) by Shawn M. Talbott, PhD and Kerry Hughes, MS.