Aloe vera is a common houseplant that has traditionally been used topically to alleviate burns and pain on the skin. Oral ingestion helps speed up intestinal motility (and has been used against constipation) and aloe vera contains a large amount of antioxidants.
Primary Information, Benefits, Effects, and Important Facts
Aloe vera is a herb traditionally used to ease digestion as a folk remedy, and to alleviate pain from burns when used topically. It has recently gained popularity as an anti-obesity agent.
Preliminary studies show benefit with aloe vera in controlling weight, but the mechanisms do not seem as potent as other anti-obesity supplements. Aloe vera is also a generally healthy compound, but has been implicated in multiple cases of liver problems (which are not too common, although resurgent) and has a lower toxicity threshold than other herbal supplements.
Aloe at normal supplementation doses has been shown to cause liver problems in some people, possibly due to a genetic susceptibility. The symptoms are reversible if the supplement is stopped.
The only human study on aloe vera used 300 mg twice daily. There is no evidence to suggest whether this is the best dose, but benefit was seen at this dosage.
The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects aloe vera has on your body, and how strong these effects are.
Grade
Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
?
The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome
Magnitude of effect
?
The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
?
Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Aloe is a genera of over 420 plants (of the family Liliaceae[1]) of which vera (sometimes referred to as Barbadensis) is the specific herb used in many supplements. Other members of this family include Aloe Ferox and Aloe Arborescens.[2] The Aloe vera plant itself is a perennial plant with turgid green leaves joined at the stem in a rosette pattern, and is most well known as a topical ointment for pain relief from burns.[3]
These plants have historically been used topically to heal wounds, and internally (consumption) as a cathartic agent[1] and have been used in Ayurveda,[4] Southern African medicine.[5]
1.2. Composition
The Aloe vera plant specifically contains:
The anthraquinone Aloin (aka. Barbalion; divided into Aloin A and Aloin B) and Isoaloin/Isobarbalion[6][7][8] and 7-hydroxyaloin A (7-OHA) and 5-hydroxyaloin A (in Aloe Ferox)[6]
Aloe vera is known to have a sensitive processing need, and can be damaged during processing.[10]
2Interactions with fat metabolism
In fat cells, it also suppresses scavenger receptor A and CD36 on macrophages in white adipose tissue.[11] These are receptors for oxidized LDL particles, and inhibiting their actions may prevent inflammatory responses. This works in concert with Aloe's ability to inhibit nuclear translocation of NF-kB in vivo.[11]
3Interactions with Oxidation
3.1. Mechanisms
The anti-inflammatory effects of aloe vera seem to be via aloesin derivatives and inhibiting both thromboxanes and COX2.[12] It has also been implicated in suppressing Nf-kB and downstream inflammatory cytokines.[11]
4Interactions with Hormones
4.1. Thyroid
In a study assessing herbal effects on the thyroid, ingestion of 125mg/kg Aloe vera for 15 days in rats was associated with a decrease in serum T4 (-12.88%) and T3 (-25.13%).[13]
5Interactions with Organ Systems
5.1. Oral Cavity
One human trial using a topical patch of 0.5% Acemannan (a polysaccharide from Aloe Vera) noted that this patch was more effective than control in reducing the size of oral aphthous ulceration (Canker Sores) when applied thrice a day for a week, but failed to outperform the active control of 0.1% triamcinolone acetonide (a topical corticosterone).[14] This has been noted elsewhere in recurrent canker sores, where thrice daily application of a gel (1.6% dry leaf remnant) was able to reduce the diameter of inflammation and pain and reduced healing time of the lesions.[15]
5.2. Liver
Aloe vera leaf gel given at 1mg/kg for a week prior to administration of alcohol (3g/kg fasted state) did not influence serum alcohol levels nor the increase in serum liver enzymes (GOP, GPT) following alcohol administration, but was able to attenuate the alcohol-induced increase in liver triglycerides via suppressing alcohol's induction of lipogenic gene mRNA expression (DGAT2, FASN, and SREBP-1; lipolytic genes not affected).[16]
1mg/kg Aloe vera can increase hepatic PPARα content by 1.3-fold relative to control without significantly influencing the target genes of CPT-1 and MCAD.[16]
6Nutrient-Nutrient Interactions
6.1. Vitamin C and Vitamin E
Coingestion of vitamin C (500mg) or vitamin E (420mg as acetate) with Aloe vera gel results in a near tripling of the Area-Under-Curve and bioavailability for both compounds[1] coupled with a delayed Tmax when consumed in a fasted state. Vitamin C went from 339+/-124 1031+/-513 and Vitamin E from 19.3+/-23.2 to 71.3+/-22.5uM/h with the addition of Aloe gel, with Aloe leaf not being statistically different from control.[1] The dose of Aloe Gel was not specified.
However, this study did not note any vitamin C or E content of the Aloe itself, and was funded by the International Aloe Science Council.[1]
7Safety and Toxicology
Aloe has been associated with acute hepatitis (liver inflammation) either in isolation[17][18] or when consumed as a multinutrient supplement.[19] These effects appear to be reversible and occur in the dosage range of 250-500mg a day, with the exact mechanism of the toxicity is not understood.
Aloe seems to cause wide-ranging side-effects at a doses 100mg/kg or greater bodyweight in animals. These side effects are observed in all subjects.[2]
