Aloe vera: A review of toxicity and adverse clinical effects

Abstract

The Aloe plant is employed as a dietary supplement in a variety of foods and as an ingredient in cosmetic products. The widespread human exposure and its potential toxic and carcinogenic activities raise safety concerns. Chemical analysis reveals that the Aloe plant contains various polysaccharides and phenolic chemicals, notably anthraquinones. Ingestion of Aloe preparations is associated with diarrhea, hypokalemia, pseudomelanosis coli, kidney failure, as well as phototoxicity and hypersensitive reactions. Recently, Aloe vera whole leaf extract showed clear evidence of carcinogenic activity in rats, and was classified by the International Agency for Research on Cancer as a possible human carcinogen (Group 2B). This review presents updated information on the toxicological effects, including the cytotoxicity, genotoxicity, carcinogenicity, and adverse clinical effects of Aloe vera whole leaf extract, gel, and latex.

Keywords: Aloe gel; Aloe vera; aloe latex; carcinogenicity; genotoxicity; toxicological effects.

Figure 1.

Representative reversed-phase HPLC profiles of Aloevera whole leaf extract and decolorized whole leaf extract. Five mg/ml samples were dissolved in Fischer’s medium with pH adjusted to 7.0-7.2. HPLC analysis was performed using a Phenomenex Prodigy 5 μmODS column (4.6 mm x 250 mm) eluted with methanol with a linear gradient of 20%−60% water over 30 min and 60-100% methanol over 30 min at a flow rate of 1 ml/min.

Figure 2.

Comparison of the percentage of mutational types for all (large and small) colonies produced in cells treated with Aloe vera. Mouse lymphoma cells were treated for 24 h with 4.5 or 5 mg/ml whole leaf extract, or 8 mg/ml decolorized extract. Whole extract at 4.5 or 5 mg/ml or decolorized extract vs control, p < 0.0001; 4.5 mg/ml whole extract vs decolorized extract, p = 0.03; 4.5 mg/ml vs 5 mg/ml whole extract, p = 0.37; 5 mg/ml whole extract vs decolorized extract, p = 0.26. Data from Table 3 in [18].