Aloe vera food supplements and drinks are supposed to help your gut stay healthy – or so herbalists claim. But now a warning flag has been raised by the US National Toxicology Program (NTP), which has found that rats given drinking water spiked with an extract of the succulent plant developed tumours in their intestines.
The rodents were given relatively high doses of a whole-leaf extract of aloe vera (Aloe barbadensis) over two years. In rats given water containing 1.5 per cent by weight of the extract, 39 per cent of females and 74 per cent of males had malignant or benign tumours in their large intestines. None of these growths were seen in rats given pure drinking water.
Mice given similar doses did not develop more tumours than normal – but rats are thought to be a better model for the risks to people, as mice have a different distribution of gut bacteria that process constituents of aloe vera.
Still, it's not yet clear what the results mean for people consuming products containing aloe vera as part of a "natural health" regime.
"At this stage, we're looking at designing the next round of experiments," says Daniel Fabricant at the US Food and Drug Administration (FDA), which contributed to the report, and is responsible for regulating dietary supplements. "We want to relate the results to the commercial products that are out there."