Evidence based medical use of aloe vera extracts, short review of literature

Abstract

The use of aloe vera is being promoted for a large variety of conditions. The aim of this review was to summarize all available research papers on aloe vera preparations with a view to providing evidence for or against its clinical effectiveness. Independent literature searches were conducted in PubMed. All studies of controlled clinical trials, observational studies and case series were included. There were no restrictions on the language of publication. All studies were read by all authors and data were extracted in a standardized, pre-defined manner. Even though there are some promising results, clinical effectiveness of oral or topical aloe vera is not sufficiently defined at present.

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International Journal of Research in Medical Sciences | October 2017 | Vol 5 | Issue 10 Page 4198
International Journal of Research in Medical Sciences
Samarh SN et al. Int J Res Med Sci. 2017 Oct;5(10):4198-4202
www.msjonline.org
pISSN 2320-6071 | eISSN 2320-6012
Review Article
Evidence based medical use of aloe vera extracts, short
review of literature
Samer N. Samarh1, Najm A. Khalaf1, Mohammed M. Hajhamad2*
INTRODUCTION
Aloe barbadensis Miller, commonly referred to as Aloe
vera, is one of more than 400 species of Aloe belonging
to family Liliaceae that originated in South Africa. Only a
few species of Aloe have been considered for commercial
importance, of which Aloe vera is considered the most
potent and, thereby, the most popular plant in the
research field. Aloe vera has been used in folk medicine
for over 2000 years, and has remained an important
component in the traditional medicine of many
contemporary cultures, such as China, India, the West
Indies, and Japan.1
Aloe vera is a succulent plant. Succulents are xerophytes,
which are adapted to living in areas of low water
availability and are characterized by possessing a large
water storage tissue. The main feature of the Aloe vera
plant is its high-water content, ranging from 99-99.5%.
The remaining 0.5-1.0% solid material is reported to
contain over 75 different potentially active compounds
including water- and fat-soluble vitamins, minerals,
enzymes, simple/complex polysaccharides, phenolic
compounds, and organic acids. It is a source of 19 out of
20 essential amino acids which is required by our body
and these amino acids help in smooth functioning of our
complex enzyme system.2
Studies have proved the antiseptic, anti-inflammatory,
antiviral and antifungal properties of Aloe vera and the
use of this plant is proved beneficial. This plant is proved
to be non-allergic and very good in building up the
immune system. Aloe vera is gaining popularity in
dentistry as it is completely natural and there are no side
effects being reported with its use. This paper gives an
overview of the uses of this miracle plant and its uses in
dentistry.3
METHODS
Computerized literature searches were performed to
identify all published articles on the subject. PubMed was
1Faculty of Quran and Sunnah Studies, University Sains Islam Malaysia, Bandar Baru Nilai 78100, Malaysia
2Department of Surgery, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
Received: 08 August 2017
Accepted: 02 September 2017
*Correspondence:
Dr. Mohammed M. Hajhamad,
E-mail: Haghamad3@gmail.com
Copyright: © the author(s), publisher and licensee Medip Academy. This is an open-access article distributed under
the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial
use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
The use of aloe vera is being promoted for a large variety of conditions. The aim of this review was to summarize all
available research papers on aloe vera preparations with a view to providing evidence for or against its clinical
effectiveness. Independent literature searches were conducted in PubMed. All studies of controlled clinical trials,
observational studies and case series were included. There were no restrictions on the language of publication. All
studies were read by all authors and data were extracted in a standardized, pre-defined manner. Even though there are
some promising results, clinical effectiveness of oral or topical aloe vera is not sufficiently defined at present.
Keywords: Aloe vera, Medical, Skin
DOI: http://dx.doi.org/10.18203/2320-6012.ijrms20174547

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International Journal of Research in Medical Sciences | October 2017 | Vol 5 | Issue 10 Page 4199
used. The bibliographies of all investigations thus located
were searched for further relevant articles. There were no
restrictions regarding publication language. All articles
(or abstracts if only available as abstracts) were read in
full. Data were extracted in a predefined fashion.
RESULTS
Diabetes mellitus
One study divided 72 diabetic women without drug
therapy into two groups. They received one tablespoon of
aloe vera gel or placebo for 42 days. Blood glucose levels
subsequently decreased from 250 mg to 141 mg
percentage in the experimental group, while controls
showed no significant changes. This study was neither
randomized nor was it blinded to patient or investigator.4
Dyslipidemia
Nasiff et al. conducted a controlled clinical trial on 60
patients with hyperlipidaemia who previously had not
responded to dietary interventions. Patients received
either 10 ml or 20 ml aloe vera or placebo daily over a
period of 12 weeks. Blood lipid levels were measured
before treatment and after four, eight, and 12 weeks.
Total serum cholesterol decreased by 15.4% and 15.5%,
triglycerides by 25.2% and 31.9%, low density
lipoprotein (LDL) by 18.9% and 18.2% respectively in
the two groups receiving aloe vera.4
Liver protection
Isolated phytosterols, namely lophenol and cycloartanol,
have the ability to induce the downregulation of fatty acid
synthesis and a tendency for upregulation of fatty acid
oxidation in the liver, which favors the reduction in intra-
abdominal fat and improvement of hyperlipidemia.
Further, addition to sterol regulatory element-binding
transcription factor 1/peroxisome proliferator-activated
receptor (PPAR)-α ratio was decreased; metabolic
syndrome-related disorders were improved and liver
steatosis in Aloe-sterol-treated Zucker diabetic fatty rats.1
Anti-oxidant effects
It has been reported by several authors that different
fractions of A. vera as well as unfractionated whole gel
have anti-oxidant effects. Glutathione peroxidase activity,
superoxide dismutase enzymes and a phenolic anti-
oxidant were found to be present in A. vera gel, which
may be responsible for these anti-oxidant effects. The A.
vera gel in a concentration of 1 in 50 also inhibited
prostaglandin E2 production from inflamed colorectal
biopsies, but had no effect on thromboxane B2 release.5
Anti-cancer
It has been documented the remarkable potential
therapeutic options of Aloe vera in cancer, wherein it
showed chemo protective effects against 1,2-
dimethylhydrazine-induced preneoplastic lesions in the
colon of Wistar rats.
Aloe vera treatment could inhibit the secretion of VEGF
in cancer cells. VEGF is one of the most important
proangiogenic cytokines known and well characterized as
an inducer of tumor neovascularization. Aloe vera
treatment significantly inhibited in vitro VEGF-induced
angiogenic response of human endothelial cells, causing
an inhibition of proliferation and migration of endothelial
cells.1
Antimicrobial
Aloe vera has been described as an antibacterial agent.
The Aloe protein of 14 kDa from the Aloe vera leaf gel
was isolated and the purified Aloe protein exhibited a
potent antifungal activity against Candida paraprilosis,
Candida krusei, and Candida albicans. Aloe vera has
anthraquinones as an active compound, which is
structural analogue of tetracycline. The anthraquinones
acts like tetracycline that inhibits bacterial protein
synthesis by blocking the ribosomal A site (where the
aminoacylated tRNA enters). Therefore, the bacteria
cannot grow in the media containing A. vera extract.1
Effect on estrogen status
Isolated emodin and aloe-emodin from Aloe vera gel
specifically suppress breast cancer cell proliferation by
targeting estrogen receptor-α protein stability through
distinct mechanisms, which suggests a possible
application of anthraquinones in preventing breast cancer
cell proliferation through estrogen receptor-α inhibition.
Aloe vera gel also helps to maintain ovarian steroid status
in polycystic ovary-like condition wherein
steroidogenesis altered and disturbed
estrogen:testosterone ratio.6
Radiation-induced injuries
Williams et al, reported two RCTs in one publication. In
the first study, they randomized 194 women receiving
radiation therapy to be treated with Aloe vera gel, self-
administered to the radiation- exposed skin twice per day
or with placebo gel. The severity of the dermatitis was
judged weekly during the 10 weeks treatment period both
by the patients and by their healthcare providers. There
was no difference between the treatment group and the
placebo group. Some clinicians participating in this trial
felt that there were fewer skin problems than normally
expected.
Thus, it was speculated that the inert carrier gel might
have had some beneficial effects. A second RCT was
therefore performed with 108 women. The only
difference compared with the first study was that the
control group now received no topical therapy at all. The
trial was therefore not blinded. Again, the results did not

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International Journal of Research in Medical Sciences | October 2017 | Vol 5 | Issue 10 Page 4200
suggest any benefit of the Aloe vera gel in terms of
prevention of radiation- induced dermatitis.7
Genital herpes
Syed et al. conducted two trials on the efficacy of Aloe
vera for first episodes of genital herpes in men. In the
first study, they randomized 120 men into three parallel
groups. Each patient applied either aloe vera cream (aloe
vera extract 0.5% in hydrophilic cream), aloe vera gel, or
placebo three times daily for two weeks. Aloe vera cream
showed shorter mean duration of healing than aloe vera
gel and placebo (4.8 days versus 7.0 and 14.0 days,
respectively). The numbers of cured patients were 70%,
45%, and 7.5%, respectively (P<0.02). Of the 49 patients
healed at the end of this trial period, six had a relapse
after 21 months of follow-up.8
Psoriasis
A study by Syed et al. randomized 60 patients with mild
to moderate chronic psoriasis to receive either an aloe
vera or placebo cream. The cream was self-applied three
times per day for four weeks. Patients were subsequently
followed up for 12 months. The cure rate in the aloe vera
group was 83% and only 7% in the placebo group. This
inter-group difference was statistically significant
(P<0.001). The cream was well tolerated. The authors
stated that, even after the follow-up period, there were no
relapses.9
Wound healing
Schmidt et al. evaluated the time interval required for
wound healing using a standard wound management
protocol with and without aloe vera gel in a randomized
controlled trial (RCT) with 40 women. All patients had
complications of wound healing after gynaecological
surgery. Only 21 of them completed the study. The mean
healing time in the conventional care group (53 days) was
significantly shorter (P<0.003) than in the aloe vera gel
group (83 days). This trial was not blinded. The details of
the standard wound management protocol were not
mentioned.10
Acne vulgaris
Fulton et al. documented the effects of two different
dressings for wound-healing management on full-faced
dermabrasion patients. Eighteen patients suffering from
acne vulgaris completed the study. Their abraded faces
were divided in half. One side was treated with a standard
polyethylene oxide gel wound dressing, while the other
side was treated with a polyethylene oxide dressing
saturated with aloe vera. After 48 hours with the aloe
vera dressing, intense vasoconstriction and a reduction in
oedema was noted; less exudate and crusting were
evident by the fourth day. By the fifth day,
reepithelialization was complete to 90% on the aloe side
compared with 40-50% on the control side. Overall,
wound healing was approximately 72 hours faster at the
aloe side.10
Dermatitis
Seborrheic dermatitis is a common inflammatory skin
disorder for which available topical treatment may be
helpful but not curative. The objective of this study was
to evaluate the effect of an emulsion formulated from a
crude extract of Aloe vera (A. barbadensis) on seborrheic
dermatitis. A double-blind, randomized, placebo-
controlled prospective clinical trial was performed in 44
adult patients with seborrheic dermatitis. A comparison
of symptom scores in the Aloe vera (A. barbadensis) and
placebo groups, before and after treatment revealed a
significant decrease in scaliness, pruritus and the number
of sites involved in seborrheic dermatitis, but not in
erythema. Global improvement rates in patients treated
with Aloe vera (A. barbadensis) were significantly higher
than in placebo-treated patients, as assessed by both
dermatologists (58% and 15%, respectively; P=0.009)
and patients (62% and 25%, respectively; P=0.03). The
results of the present study indicate that Aloe vera (A.
barbadensis) crude extract emulsion is effective in the
therapy of patients with seborrheic dermatitis.12
Treatment of burns
In a clinical study, to check the efficacy of A. vera gel
compared with 1% silver sulfadiazine cream as a burn
dressing for the treatment of superficial and partial
thickness burns, healing of burn wounds was remarkably
early in A. vera treated patients than those patients treated
with 1% silver sulfadiazine.13
Dentistry
Having good antiseptic and anti-inflammatory properties
they are used in the treatment of gingivitis and
periodontitis. They readily reduce the gingival
inflammation and pain associated with it. Clinically
proven studies have showed that mouth rinses and
dentifrices containing aloe vera have shown a remarkable
reduction in gingivitis and plaque accumulation after its
use.14
Eye diseases
Aloe vera contains multiple pharmacologically active
substances which are capable of modulating cellular
phenotypes and functions. Aloe vera ethanol and ethyl
acetate extracts may be used in eye drops to treat
inflammations and other ailments of external parts of the
eye such as the cornea.15
Ocular surface squamous neoplasia
The patient refused biopsy of this lesion (Figure 1), and
traditional treatments and, instead, initiated using A. vera
eye drops 3 times daily. At follow-up visits, the lesion

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was noted to regress (Figure 2) until it finally resolved 3
months after commencing treatment. No additional
topical medications were used, and she has remained
tumor free for 6 years.16
Figure 1: Gelatinous 4.4 mm lesion arising at the
medial limbus of the left eye with prominent feeder
vessels, at the time of the patient’s initial consultation
visit.
Figure 2. Rose Bengal staining demonstrating
complete regression of the lesion after the patient used
a topical A. vera formulation for 3 months.
Adverse effects of aloe vera
No withdrawals owing to adverse effects of aloe vera
were reported in any of the above trials. Some patients
experienced burning after topical application, contact
dermatitis and mild itching.3,7,8 All adverse effects were
reversible and aloe vera was generally very well
tolerated.
DISCUSSION
To the best of our knowledge, this is the first systematic
review on this subject. In view of the widespread use of
aloe vera, perhaps the most surprising finding is the
paucity of controlled clinical trials. Furthermore, the few
studies that are available are by no means free of
methodological flaws. Lack of randomization, lack of
blinding, small sample size, lack of intention-to-treat
analyses, and lack of power calculation are some
prevalent limitations. Furthermore, it is noteworthy that
trials tend to originate from the same research groups,
and independent replications are, by and large, lacking.
Thus, it is problematic to draw firm conclusions from this
review.
The question arises whether aloe vera is safe. Studies in
mice revealed no acute toxicity in therapeutic doses. In
high doses, however, a decrease of CNS activity was
noticed. During chronic treatment, there was a decrease
in red cell count and significant sperm damage.17 No
systematic investigations exist in humans. In the
reviewed trials, no withdrawals or serious adverse
reactions were reported.1
CONCLUSION
It is concluded that there is some preliminary evidence to
suggest that oral administration of aloe vera might be
effective in reducing blood glucose in diabetic patients
and in lowering blood lipid levels in hyperlipidemia. The
topical application of aloe vera does not seem to prevent
radiation-induced skin damage. It might be useful as a
treatment for genital herpes and psoriasis. The evidence
regarding wound healing is contradictory. More and
better trial data are needed to define the clinical
effectiveness of this popular herbal remedy more
precisely.
Funding: No funding sources
Conflict of interest: None declared
Ethical approval: Not required
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Cite this article as: Samarh SN, Khalaf NA,
Hajhamad MM. Evidence based medical use of aloe
vera extracts, short review of literature. Int J Res
Med Sci 2017;5:4198-202.