On Gastrointestinal Function In Normal Humans
This study evaluated the effect of oral Aloe vera juice supplementation on gastric pH, stool specific gravity, protein digestion/absorption, and stool microbiology.
Results indicate that supplemental oral Aloe vera juice is well tolerated by most individuals and has favorable effects upon a number of gastrointestinal parameters.
A discussion of the potential role of Aloe vera juice on inflammatory bowel disorders based upon this work is presented.
Members of the genus Aloe Barbadensis and Aloe vera have been used historically for medical purposes. Going back to ancient Phoenician literature, historical records chronicle the application of internal contents of the leaves of the Aloe plant for the treatment of burns, wounds, and other dermatological conditions.
The pharmacological principle(s) in Aloe has been the subject of great controversy throughout this history. In recent years, individuals have extracted the Aloe plant looking for specific nutritional agents, alkaloids, sapponins, fatty acid materials, glycoproteins, or terpenoid substances that may account for its unique ability to promote healing of the dermis. This research has uniformly resulted in failure to identify the active principle in Aloe. It has been suggested that the extract of the Aloe plant promotes tissue reparation through the complex synergistic interaction of many substances, including vitamins, mineral amino acids, and other small constituent molecules that are members of the terpenoid family. Substances such as Aloe-Emodin or Aloe Resin-A have been evaluated recently from Aloe extraction concentrates as being terpenoids, characteristic of Aloe potency.
A great challenge still exists to phytochemists to try to better define what the physiochemical agents in Aloe are that demonstrate activity. The clinical evidence mounts, however, that topical application of Aloe extracts or the excised phloem material of the Aloe plant itself has repeatedly been demonstrated to have significant ability in promotion vascularizing, reducing edema and inflammation, while promoting epidermal growth and differentiation.
Recent studies of Cera, Heggers, and Hagstrom in animals have indicated that the topical administration of Aloe extract to dogs with certain forms of dermatitis can result in significant improvement of the dermatological condition when contrasted to control animal.
They postulate that Aloe vera has both bacteriostatic and prostaglandin-suppressor activity when applied to the dermis.
Concomitant with these observations of the abilities of the extract of the Aloe plant as a bacteriostatic substance when administered topically are the historical reports that Aloe vera, when ingested orally, also has a systemic influence both on improvement of gastrointestinal function and possibly even other important physiological relationships.
Individuals who have suffered from indigestion, irritable bowel syndrome, colitis, and excess acid stomach, have reported relief from these conditions by the oral administration of Aloe vera juice. The physiological effects of orally administered Aloe vera juice on gastrointestinal function has not been studied under controlled conditions. Such a study is essential to establish the role that orally administered Aloe vera juice plays in imparting favorable gastrointestinal functional changes.
To address this particular question, the following study was designed. This study evaluates the impact of orally consumed Aloe vera juice on gastrointestinal function by evaluation of colonic bacterial activity, gastrointestinal pH, impact upon stool specific gravity, and gastrointestinal motility in normal subjects.
This study involved ten healthy subjects – five men (median age: 42; standard deviation: 14 years), and five women (median age: 32; standard deviation: 5 years) – engaged in a semicontrolled Aloe vera juice oral supplementation study protocol.
During the course of this study, they were not asked to eat any special foods nor to engage in an alternative scheduling of their time, but rather maintain their normal diets and lifestyles.
The subjects’ initiated entry into the study by reporting after fasting overnight for an evaluation of their gastric acid secretion by the Heidelbergradiotelemetry procedure. This procedure involves the swallowing of a small pH sensitive capsule, which then transmits back to a receiver worn around the waist the internal pH of the stomach and duodenum. This procedure allows for in vivo quantification of gastrointestinal pH with position of the capsule in the gastrointestinal tract and also after the challenge with various foods.
After time was allowed for the capsule to equilibrate in the stomach, a meal replacement bar was consumed to stimulate hydrochloric acid output. This meal replacement bar contained 40% of its calories as protein, 50% of its calories as carbohydrate, and 10% of its calories as fat with RDA levels of vitamins and minerals. After one hour, six ounces of water was consumed and the patient asked to sit upright to allow the capsule to travel into the duodenum where the pH was monitored for another two and one-half hours. A stool sample and a morning urine sample were also taken after the completion of the Heidelberggastrogram.
The urine was analyzed for the presence of indoxyl-sulfate, a metabolite of tryptophan produced in the bowel by the action of gastrointestinal bacteria on unabsorbed dietary protein. Indoxyl-sulfate in the urine is indicative of the degree to which either dietary protein is being malabsorbed or intestinal colonic bacteria are engaged in a putrefactive process. The stool sample had its specific gravity measured and was assayed for microbiota by a stool culture with specific focus on pathogenic bacteria.
After completion of these first battery of tests, each subject was then asked to consume six ounces of Aloe vera juice (concentrate juice) taken in two-ounce increments three times daily each day for seven days. After seven days on an ad lib diet with Aloe vera juice supplementation, each subject was then evaluated by the identical procedure to that in the initial phase of the experiment. The only modification of the program was the addition of six ounces of Aloe juice at the first hour of theHeidelberggastrogram rather than six ounces of water.
Comparison of the post-Aloe vera supplementation stool culture, urinary indican, and Heidelberg gastrogram to that of the pre-Aloe vera challenge allowed for the determination of the impact that Aloe vera juice supplementation has upon gastrointestinal function as measured through bacterial activity of the colon, bowel transmit time, gastric pH, and stool density.
Evaluation of the data collected on each subject before and after Aloe vera juice supplementation produced information on the average changes in urinary indican, stool specific gravity, gastric pH, and bowel motility.
As can be seen from Table 1, urinary indican values were seen to decrease on the average, one full unit after the Aloe vera juice intake for one week. This is indicative oflowered bowel bacterial conversion of tryptophan and possibly improved protein digestion and absorption after the Aloe vera juice treatment.
Increased urinary indican is reflective of reduced protein digestion and absorption and increased bowel putrification of the amino acid tryptophan, and the lower value of urinary indican seen after the Aloe vera juice supplementation trial, suggests improved protein digestion assimilation with reduced bacterial putrefaction.
Urinary Indican Levels
Before & After Aloe Vera Trial
Subject Sex Before* After*
Average change – 1.0 indican units
*Values rated from zero to 4: highest
indican = 4
Excerpts By Jeffrey Bland, Ph.D.
Linus Pauling Institute of Science & Medicine
Preventive Medicine, March/April 1985