Aloe vera has been used as a medicinal plant for thousands of years. During the vast majority of that time Aloe vera leaves were cut from the plant and used immediately for a wide variety of medicinal applications ranging from soothing and healing of minor cuts and burns to treatment of a variety of stomach ailments. As knowledge of Aloe vera\'s medicinal properties spread efforts were made to harvest, preserve and store Aloe vera for ease of access and transportation to regions where Aloe vera did not readily grow. It was soon noticed that Aloe vera\'s lost most of its potency soon after the leaf was cut from the plant.
In the early 20th century modern science was applied to identify the active ingredients in Aloe vera and design cultivation, harvesting and processing methods to preserve, store, and introduce Aloe vera into wider commercial markets. During this time many different methods were used to produce Aloe vera products. Unfortunately, armed with today\'s knowledge and experience, we now recognize that many of these early methods actually destroyed the beneficial medicinal properties of Aloe vera. The inconsistent quality of Aloe vera preparations led to a number of conflicting scientific studies. Further, it led to the introduction of many products into the market place of variable quality resulting in conflicting consumer experiences. Collectively this has resulted in controversy about the true medicinal benefits of Aloe vera.
Recent scientific surveys of commercial Aloe vera products have revealed the inconsistency of the active Aloe vera content present in Aloe vera preparations and products. (1-3) On a commercial scale, Aloe vera is usually grown and processed by 'supply companies'. Supply companies then sell processed aloe to product manufacturing companies who in turn use it as a raw material in the manufacture of a wide range of commercial products. Thus if a supply company is releasing an inferior processed aloe product, it will be used by many different product companies in the manufacture of many different products.
One study of processed aloe from various supply companies dramatically revealed the inconsistency in quality of aloe vera raw material. (2) Samples were obtained from 9 of the leading international suppliers of Aloe vera powder. The primary measures used in this study were the amount of Acemannan, the main active ingredient in Aloe vera gel, and the presence of adulterants, impurities, and preservatives. The results were both surprising and disturbing. Only 3 of the samples contained satisfactory amounts of Acemannan (10 w/w).
The remaining 6 samples had Acemannan concentrations below what is considered necessary to be effective. Four samples showed evidence of bacterial contamination, and one sample had abnormally high glucose concentration (30). Aloin A is a compound found in the outer skin of the aloe leaf and has strong laxative properties. Aloin A can be used as a measure of contamination of aloe gel during processing. 3 of the samples contained no detectable Aloin A. 5 of the samples had Aloin A concentrations ranging from 0.1 mg/kg to 15.9 mg/kg. One sample was not analyzed for Aloin A content. Collectively these data show dramatic inconsistencies in processed aloe that is available as a raw material used in the manufacture of commercial products.
A second study focused on the amount and quality of Aloe vera content in 31 commercial products. As might be predicted from the Bozzi study (2) described above there was a corresponding wide range of amount and quality of aloe found in commercial products. Acemannan is viewed as the major active ingredient in Aloe vera gel. It is a very large molecule and its activity is critically dependent upon its size. (4) In this study the investigators measure the actual size of Acemannan in the products tested. Studies have shown that the optimal size of Acemannan is between 5 kDa and 400 kDa where kDa is a measure of molecular size. (4) In fresh gel 9.15 of the Acemannan present was has a size of greater than 10 kDa. The majority of products showed that less than 2 of the Acemannan present was greater than 10 kDa. Many of these products were labeled as 200X concentrates. Thus even if Acemannan is present in many cases it was too small to be active. A notable few of the samples showed that greater than 10 of the Acemannan had a size of greater than 10 kDa. These results show the wide variation in the Acemannan content and quality of Aloe vera products available on the market and suggest that in many that aloe content likely provides no medicinal value at all.
We now know that Acemannan is not stable under a variety of conditions used during the manufacturing process include heat, acid, enzymes released from cells during processing. (5) Many different processing methods have been developed with variable results. Today there is no standard quality control test that is universally applied to processed aloe vera and products prepared from process Aloe vera. Although promising methods have been reported they have not been widely adopted by manufactures. (6) The International Aloe Science Council (IASC) was established to help develop standards for aloe products and publishes a list of IASC Certified aloe products. (7)
Aloe\'s long rich history as a medicinal plant and modern scientific research strongly suggest that Aloe vera has many beneficial medicinal properties. Unfortunately, until minimum quality control standards are developed and universally applied, the consumer will be at risk of purchasing low quality, ineffective aloe products.
More information can be found on the The Science Behind Aloe vera blog.
Literature Cited
1. Turner, C.E., Williamson, D.A., Stroud, P.A., and Talley, D.J. (2004). Evaluation and Comparison of Commercially Available Aloe Vera L. Products Using Size Exclusion Chromatography with Refractive Index and Multi-Angle Laser Light Scattering Detection. Int Immunopharmacol 4:1727-1737. http://www.ncbi.nlm.nih.gov/pubmed/15531289
2. Bozzi, A., Perrin, C., Austin, S., and Vera, F. (2007). Quality and Authenticity of Commercial Aloe Vera Gel Powders. Food Chemistry 103:22-30. http://www.aseanfood.info/Articles/11018276.pdf
3. Ross, S.A., Elsohly, M.A., and Wilkins, S.P. (1997). Quantitative Analysis of Aloe Vera Mucilaginous Polysaccharide in Commercial Aloe Vera Products. Journal of AOAC International 80:455-457
4. Im, S.A., Oh, S.T., Song, S., Kim, M.R., Kim, D.S., Woo, S.S., Jo, T.H., Park, Y.I., and Lee, C.K. (2005). Identification of Optimal Molecular Size of Modified Aloe Polysaccharides with Maximum Immunomodulatory Activity. Int Immunopharmacol 5:271-279. http://www.ncbi.nlm.nih.gov/pubmed/15652758
5. Femenia, A., and Garcia-Pascual, P. (2003). Effects of Heat Treatment and Dehydration on Bioactive Pollsaccharide Acemannan and Cell Wall Polymers from Aloe Babadensis Miller. Carbohdrate Polymers 51:397-405
6. Eberendu, A.R., Luta, G., Edwards, J.A., Mcanalley, B.H., Davis, B., Rodriguez, S., and Ray Henry, C. (2005). Quantitative Colorimetric Analysis of Aloe Polysaccharides as a Measure of Aloe Vera Quality in Commercial Products. Journal of AOAC International 88:684-691
7. The International Aloe Science Council Web Site. (2011). Companies, Finished Products & Raw Materials Completing Certification. Accessed May 6, 2011. http://www.iasc.org/complete.html
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About the Author
Dr.Cowsert received his Bachelors of Science degree from the University of Florida,
(Gainesville) and his PhD from Georgetown University Medical School (Washington, DC) where he focused on the molecular biology, immunobiology, and pathology of Human Papillomaviruses. He completed his postdoctoral studies at The National Cancer Institute (Bethesda, MD). Dr. Cowsert has over 20 years\' experience in the biotechnology industry where he has held positions of increasing responsibility from Senior Research scientist to executive C-level management positions. During his tenure in the biotechnology industry Dr. Cowsert lead multiple drug discovery teams and worked on multiple drug development teams with direct interactions with the FDA. Much of Dr. Cowsert\'s scientific work has been supported by over $5M in highly competitive government grants from the National Institutes of Health and the National Cancer Institute. Dr. Cowsert has written many peer reviewed scientific articles and book chapters and has been an Editor for a peer reviewed scientific journal for 10 years. He has been an invited speaker at over 25 international scientific meetings and is an inventor on 140 issued US Patents. Dr. Cowsert has been an expert guest on many health talk radio shows.
