Aloe: does the medicinal plant promote cancer?
Dr. Andrea Bannert has been with since 2013. The doctor of biology and medicine editor initially carried out research in microbiology and is the team's expert on the tiny things: bacteria, viruses, molecules and genes. She also works as a freelancer for Bayerischer Rundfunk and various science magazines and writes fantasy novels and children's stories.
More about the experts All content is checked by medical journalists.The green, fleshy leaves of the aloe plants have been said to have true miraculous powers for centuries. They are supposed to beautify the skin, support wound healing and also stimulate digestion. But now authorities are warning of certain ingredients of the medicinal plant: They could promote colon cancer.
Aloe plants live in the desert and store large amounts of water in the gel, which is hidden inside their leaves. This leaf pulp is often used in creams and ointments. But aloe is also used in pill form and as a dietary supplement.
Good for constipation
They stimulate digestion and have a laxative effect: capsules, juices, yogurts with aloe help as herbal remedies against constipation and other digestive problems. For this, however, not only the gel of the aloe plant is used, but the whole plant or a dry extract from the outer leaf layers. Because it contains so-called hydroxyanthracenes. The active ingredients emodin and danthron in particular stimulate the muscle activity of the intestine.
Outer leaf layers under suspicion
But precisely these healing substances could also damage the DNA. This is the conclusion of the European Food Safety Authority (EFSA). Previously, experts evaluated all studies carried out so far that examined the effects of aloe extracts.
Animal studies as well as cellular and human epidemiological studies suggest that aloe preparations made from whole leaves could cause cancer.
Laxatives with dangerous side effects
Mice that had been fed aloe extract from the whole plant or directly fed danthron for a long period of time were more likely to develop colon cancer compared to rodents without aloe in the diet. "In addition, people who regularly take laxatives also get colon cancer more often," reports Francesca Avanzini, spokeswoman for EFSA to Many of these supplements contain hydroxyanthracenes.
DNA repair slowed down
The researchers do not yet know in detail how exactly the aloe ingredients damage the DNA. However, several mechanisms seem to play a role. On the one hand, the dangerous phytonutrients push themselves into the DNA strands - they intercalate, as we say in the technical jargon. If the cell then duplicates the genetic material in order to divide, it inserts a wrong component in the appropriate place and a so-called mutation occurs.
In addition, the hydroxyanthracenes also act on the DNA repair system in the cell. When copying the DNA, a lot of mistakes naturally happen, but most of them are fixed again by the repair team. The substance from the aloe leaves inhibits these repair mechanisms. The result: more errors go undetected and the risk of cancer increases.
No aloe leaves in food
“We cannot say exactly how much aloe leaves are carcinogenic,” said the EFSA spokesman. "That is why they should not be used in foods or dietary supplements."
The German Federal Office for Risk Assessment (BfR) comes to a similar assessment: "When producing food with leaves from plants of the Aloe genus, the outer leaf layers should be carefully removed in order to keep contamination with hydroxyanthracenes as low as possible," the experts write in a statement.
No warning about ointments and creams
This does not affect creams and ointments that only contain the gel-like leaf pulp. It is supposed to moisturize the skin. The gel is also said to have a wound healing effect, which could help with sunburn, wounds, burns, acne, insect bites or inflammatory skin diseases. Unlike the digestive effects, however, this has not been proven.
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