What is Aloe?
Aloe is a succulent plant widely
used in alternative medicine. There
are at least 420 different plant species
of Aloe. Aloe vera specifically refers
to the Aloe barbadensis Miller plant,
which is the most common form
used in Aloe-based products.
How is Aloe used?
Traditionally, the clear gel from the
Aloe plant is rubbed on the skin as
an ointment to treat wounds and
burns. The green part of the leaf
can be made into a juice or dried
and taken orally as a laxative. Aloe
vera is used in many commercial
products in various forms, including
drinks, concentrates, capsules,
powders, and as a flavoring.
Why did the NTP study Aloe?
The nomination to study Aloe
vera came from the National
Cancer Institute, because of Aloe’s
widespread use and concern that
some components may cause cancer.
The NTP studies on Aloe vera were
conducted in collaboration with the
Food and Drug Administration’s
National Center for Toxicological
Research.
What did the NTP study find?
The two-year NTP study of a
non-decolorized whole leaf extract
of Aloe vera given in an animal’s
drinking water found clear evidence
of carcinogenic activity in male and
female rats, based on tumors of the
large intestine. There was no evidence
of carcinogenic activity in mice.
NTP did not conduct two-year
studies of ingestion of the Aloe vera
gel or of the plant’s decolorized
whole leaf extracts.
The difference between decolorized
and non-decolorized whole leaf
extracts is mostly in how the leaf
is processed or filtered. In many
cases, manufacturers of oral
products containing Aloe vera
use a charcoal filtration process to
decolorize and remove some of the
components from the leaf, including
anthraquinones. Anthraquinones act
like laxatives. Some anthraquinones
have previously been shown to be
carcinogenic.
What if I use Aloe vera gel on my
skin, will it cause me harm?
Applying Aloe vera gel on the skin
is not likely to cause harm. Although
these particular NTP studies only
looked at oral exposure to Aloe vera,
other NTP studies examined the
effects of the gel on the skin and
did not find a strong link between
Aloe vera in skin care products,
sunlight, and the development
of skin cancer. The results of those
skin studies were reported in NTP
Technical Report 553: http://ntp.
niehs.nih.gov/ntp/htdocs/LT_rpts/
TR553.pdf.
Why would people consume
drinks that have Aloe in them?
Product advertisements claim
the drinks can be used to cleanse
the digestive system or relieve
constipation.
What makes Aloe act like a laxative?
An organic component in the outer
leaf pulp of Aloe leaves, known as
the latex, contains anthraquinones.
Aloin is an example of an
anthraquinone found in the
latex that may give the plant
its laxative qualities.
How much aloin is in products
in the U.S. that may be consumed
by the public?
There are very little data about
what the levels of aloin are in the
consumer products. According to
published research, levels of aloin
in most liquid products are less than
1 part per million (ppm); however,
levels in solid or semi-solid products
may be 10-100 times higher.
The two-year NTP study on consumption of
non-decolorized whole leaf extract of Aloe
vera found clear evidence of carcinogenic
activity in male and female rats, based on
tumors of the large intestine. From what
we know right now, there is nothing that
would lead us to believe that these findings
are not relevant to humans. However, more
information, including how individuals use
different types of Aloe vera products, is
needed to determine the potential risks
to humans.
Aloe Vera
Headquartered at the
National Institute of Environmental
Health Sciences NIH-HHS
PO Box 12233 • Research Triangle Park, NC 27709
Phone: 919-541-3345 • http://ntp.niehs.nih.gov
April 2011 Printed on recycled paper
How much aloin
is in a typical drink?
This is not clear. Industry usually
processes the Aloe vera leaf to make
a decolorized whole leaf extract
to remove aloin. Industry has a
self-regulated upper limit standard
of 10 ppm of aloin in orally ingested
products, but there are no labeling
requirements for aloin content.
What are the adverse effects
of excessive Aloe exposure
in humans?
More research is needed to answer
this question. In rodents, it caused
intestinal tumors.
If you are concerned, have a
medical condition, or are taking
other drugs, herbs, or supplements,
you should speak with your
physician before altering existing
treatments or starting any
new treatment.
How similar are the doses of aloin
in the drinking water fed to the
animals to those found in
Aloe vera products?
This is not clear, as there are no
labeling requirements to list aloin
content. The concentration of aloin
in the water that the rodents drank
in the NTP study is similar to that
found in some Aloe vera products,
but higher than in other products.
The NTP wanted to test an Aloe
preparation that includes all
components that may be in
the products on the market.
The NTP study used a whole leaf
extract of Aloe barbadensi