The use of dietary supplements by patients with cancer has increased significantly over the past 2 decades despite insufficient evidence of safety and effectiveness. Finding reliable sources of information about dietary supplements can be daunting. Patients typically rely on family, friends, and the Internet, often receiving misleading information.
The ASCO Post’s Integrative Oncology series is intended to facilitate the availability of evidence-based information on integrative and complementary therapies commonly used by patients with cancer. We chose Aloe vera for this issue because of its growing popularity among cancer patients.
Compiled by Barrie R. Cassileth, PhD, and Jyothi Gubili, MS, Memorial Sloan Kettering Cancer Center. The free About Herbs website is managed by K. Simon Yeung, PharmD, MBA, LAc, Memorial Sloan Kettering Cancer Center.
Aloe Vera
Scientific names: Aloe vera, Aloe barbadensis, Aloe capensis
Common names: Burn plant, lily of the desert, elephant’s gall, cape aloe, first aid plant, ghai kunwar, Sabila
Overview
A perennial succulent plant, Aloe vera belongs to the lily family and resembles a cactus. It is prevalent in Asia, Africa, and other tropical areas and is easily propagated in dry climate. Aloe has a long history of traditional medicinal use, dating back to ancient Egypt, where it was used as a remedy for burns and skin conditions.
Aloe leaves are the source of a clear thick gel, which is used topically to treat burns, psoriasis, and frostbite as well as for wound healing. It is used orally for ulcerative colitis, diabetes, and constipation.
Aloe is marketed in the form of juice, softgels, capsules, and ointments. It is also a common ingredient in many cosmetics including lotions and creams. Although aloe is used to relieve constipation, the U.S. Food and Drug Administration ruled its use as a stimulant laxative unsafe.1 Aloe products are promoted to patients with cancer, especially for use against radiation-induced skin toxicity, despite the absence of strong evidence.
The Science
Aloe demonstrated antioxidant, anti-inflammatory,2 immunomodulatory, and anticancer3,4 properties in vitro. Aloe emodin, a compound in aloe, was shown to enhance the effects of radiation in HeLa cells.5 The anthracenes and anthraquinones are responsible for aloe’s antiproliferative effects, whereas the immunostimulating property is conferred mainly by acemannan.6 In a study of patients with second-degree burns, topical aloe was found to be superior to the commonly used silver sulfadiazine cream.7 An aloe gel complex was shown to benefit obese individuals with early untreated diabetes by affecting reductions in body weight and insulin resistance.8
The anticancer potential of aloe has been investigated in a few studies. The concurrent use of oral aloe with chemotherapy resulted in tumor regression and improved survival in patients with metastatic cancers.6 Results of a systematic review suggested that aloe also may help to prevent chemotherapy-induced oral mucositis.9 However, data are inconsistent about whether it can help repair radiation therapy–induced skin damage.10,11
Adverse Effects
Inappropriate use of aloe supplements has been linked to thyroid dysfunction.12 A case of hypokalemia was reported with use of aloe during chemotherapy.13 Toxic hepatitis was seen following use of aloe preparations; liver function was normalized after discontinuation of aloe.14 A National Toxicology Program study showed that long-term exposure to aloe was carcinogenic in rats,15 although studies in humans have not been conducted.
Herb-Drug Interactions
Cytochrome P450 substrates: Aloe juice was found to inhibit CYP3A4 and CYP2D6 in vitro and may affect the intracellular concentration of drugs metabolized by these enzymes.16 (It has been estimated that CYP3A4 metabolizes about half of all drugs on the market, and CYP2D6 metabolizes about 20% of these drugs.) ■
Disclosure: Ms. Gubili reported no potential conflicts of interest.
References
1. Food and Drug Administration. Status of Certain Additional Over-the-Counter Drug Category II and III Active Ingredients. http://www.fda.gov/ohrms/dockets/98fr/050902a.htm. Accessed November 26, 2014.
2. Yagi A, Kabash A, Okamura N, et al: Antioxidant, free radical scavenging and anti-inflammatory effects of aloesin derivatives in Aloe vera. Planta Med 68:957-960, 2002.
3. Pugh N, Ross SA, ElSohly MA, Pasco DS: Characterization of Aloeride, a new high-molecular-weight polysaccharide from Aloe vera with potent immunostimulatory activity. J Agric Food Chem 49:1030-1040, 2001.
4. Lee KH, Kim JH, Lim DS, Kim CH: Anti-leukaemic and anti-mutagenic effects of di(2-ethylhexyl)phthalate isolated from Aloe vera Linne. J Pharm Pharmacol 52:593-598, 2000.
5. Luo J, Yuan Y, Chang P, et al: Combination of aloe-emodin with radiation enhances radiation effects and improves differentiation in human cervical cancer cells. Mol Med Rep 10:731-736, 2014.
6. Lissoni P, Rovelli F, Brivio F, et al: A randomized study of chemotherapy versus biochemotherapy with chemotherapy plus Aloe arborescens in patients with metastatic cancer. In Vivo 23:171-175, 2009.
7. Khorasani G, Hosseinimehr SJ, Azadbakht M, et al: Aloe versus silver sulfadiazine creams for second-degree burns: A randomized controlled study. Surg Today 39:587-591, 2009.
8. Choi HC, Kim SJ, Son KY, et al: Metabolic effects of aloe vera gel complex in obese prediabetes and early non-treated diabetic patients: Randomized controlled trial. Nutrition 29:1110-1114, 2013.
9. Worthington HV, Clarkson JE, Bryan G, et al: Interventions for preventing oral mucositis for patients with cancer receiving treatment. Cochrane Database Syst Rev Apr 13;(4):CD000978, 2011.
10. Heggie S, Bryant GP, Tripcony L, et al: A phase III study on the efficacy of topical aloe vera gel on irradiated breast tissue. Cancer Nurs 25:442-451, 2002.
11. Olsen DL, Raub W Jr, Bradley C, et al: The effect of aloe vera gel/mild soap versus mild soap alone in preventing skin reactions in patients undergoing radiation therapy. Oncol Nurs Forum 28:543-547, 2001.
12. Pigatto PD, Guzzi G: Aloe linked to thyroid dysfunction. Arch Med Res 36:608, 2005.
13. Baretta Z, Ghiotto C, Marino D, Jirillo A: Aloe-induced hypokalemia in a patient with breast cancer during chemotherapy. Ann Oncol 20:1445-1446, 2009.
14. Yang HN, Kim DJ, Kim YM, et al: Aloe-induced toxic hepatitis. J Korean Med Sci 25:492-495, 2010.
15. Boudreau MD, Beland FA, Nichols JA, Pogribna M: Toxicology and carcinogenesis studies of a nondecolorized [corrected] whole leaf extract of Aloe barbadensis Miller (Aloe vera) in F344/N rats and B6C3F1 mice (drinking water study). Natl Toxicol Program Tech Rep Ser Aug(577):1-266, 2013.
16. Djuv A, Nilsen OG: Aloe vera juice: IC50 and dual mechanistic inhibition of CYP3A4 and CYP2D6. Phytother Res 26:445-451, 2012.
For additional information, visit the “About Herbs” website at http://www.mskcc.org/cancer-care/herb/aloe-vera.
GUEST EDITOR
Integrative Oncology is guest edited by Barrie R. Cassileth, MS, PhD, Chief of the Integrative Medicine Service and Laurance S. Rockefeller Chair in Integrative Medicine at Memorial Sloan Kettering Cancer Center, New York.
The Integrative Medicine Service at Memorial Sloan Kettering Cancer Center developed and maintains a free website—About Herbs (www.mskcc.org/aboutherbs)—that provides objective and unbiased information about herbs, vitamins, minerals, and other dietary supplements, and unproved anticancer treatments. Each of the close to 300 and growing number of entries offer health-care professional and patient versions, and entries are regularly updated with the latest research findings.
In addition, the About Herbs app, Memorial Sloan Kettering Cancer Center’s very first mobile application, can be downloaded at http://itunes.apple.com/us/app/about-herbs/id554267162?mt=8. The app is compatible with iPad, iPhone, and iPod Touch devices.
