Aloe is a genera of over 420 plants (of the family Liliaceae) 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. 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.
The Aloe vera plant specifically contains:
Anthraquinones Aloresin A and B
With some bioactive polysaccharides
Aloe vera is known to have a sensitive processing need, and can be damaged during processing.
In fat cells, it also suppresses scavenger receptor A and CD36 on macrophages in white adipose tissue. 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.
The anti-inflammatory effects of aloe vera seem to be via aloesin derivatives and inhibiting both thromboxanes and COX2. It has also been implicated in suppressing Nf-kB and downstream inflammatory cytokines.
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%).
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). 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.
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).
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.
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 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. 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.
Aloe has been associated with acute hepatitis (liver inflammation) either in isolation or when consumed as a multinutrient supplement. 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.