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Your Environment. Your Health.

NTP Speaks about Aloe Vera

Dr. Nigel Walker

The National Toxicology Program (NTP) conducted studies to help clarify the potential health hazards from ingestion of certain types of aloe vera. The National Toxicology Program (NTP) is a federal, interagency program, headquartered at the NIEHS, whose goal is to safeguard the public by identifying substances in the environment that may affect human health.

Dr. Nigel Walker, Deputy Program Director for Science for the National Toxicology Program, discusses NTP Technical Report on the Toxicology and Carcinogenesis Studies of A Nondecolorized Whole Leaf Extract of Aloe Barbadensis Miller (Aloe Vera) below. The NTP Studies on Aloe vera were conducted in collaboration with the Food and Drug Administration's .

Speaker and Topic Transcript
What is Aloe Vera?
Aloe is a large group of different succulent plants and there's over 400 different species of Aloe. When we're thinking of Aloe vera, we're actually referring to a specific species, Aloe barbadensis Miller, which is commonly known at Aloe vera. You can make many different kinds of products from Aloe vera, be it capsules, powders, drinks, creams, gels, and most of the dietary supplements and herbal medicines are based on products derived from Aloe vera. Now, that's not the same as the Aloe that you see growing in your yard - that's a different species. The bioactive component of Aloe vera is really the anthraquinones and the highest constituent anthraquinone is aloin - aloin A - which we measured with our studies - the aloin is actually what causes the laxative effect, and actually is recognized by FDA [U.S. Food and Drug Administration] as a laxative, and it was actually removed from over-the-counter laxatives, because of insufficient safety information.
Next Steps: Using NTP Study to Determine Risks to Humans
Our NTP studies evaluate hazard. They are primarily designed to identify hazards, as part of the risk assessment process. But, the risk assessment process is based on three different things: it's identifying hazard, understanding the dose response for that hazard, and understanding exposure, for humans in particular. You have to integrate all three, to determine risk. Firstly, are those tumors anything unusual that would only be rat specific or rodent specific? There's nothing we know at this time that would lead us to think that these are rodent specific. We've done some studies looking at the patterns of DNA changes in those tumors, and those are consistent with intestinal tumors in humans. So, we believe that the actual tumors are relevant to humans. The next step would be, how do you... So, that will identify these if they are a potential hazard. To translate that to a human risk, we need to know exposure. Now, that's where we have very little information. That wasn't part of this study. We need to know how much people are exposed to, for how long, and what magnitude. That would then allow you to translate to potential risk in humans.
The NTP Study: What We Studied and What We Found
The most recent study we looked at the long-term health effects of nondecolorized Aloe vera whole leaf extract in both rats and mice. And, in that study we found that it caused cancer in the intestines of the rats. So, these animals basically they drank Aloe nondecolorized whole leaf extract that was formulated in their drinking water, for basically almost their whole lifetime. So, every day they were drinking water that contained the extract. And, at the end of the two-year studies, we found that particularly in rats, and especially in the male rats, there were increases in intestinal tumors, in both the males and the female rats.
Take Home Message
The Aloe gel, which is used in skin care products, is generally believed to be safe. So, really there are three points I'd like to make from the NTP studies. Firstly, that within these NTP studies, we found there was clear carcinogenic activity of the nondecolorized whole leaf extract, in both male and female rats, based on the increase in large intestinal tumors. Now, secondly, we believe these are relevant to humans. Thirdly, how this translates to human risk requires more information. We particularly need to know what are the constituents, what's the levels of those constituents in human products, and what's the patterns of human exposure. That allows you to translate that to human risk.
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