Posted by: Hourglass PJ14 APR 2010
Blue agave (Agave tequilana), the plant used to produce the drink tequila, may find a use in functional foods, ie, foods with potential health benefits beyond their nutritional content. Indeed, its nectar (syrup) has been marketed as an alternative sweetener for some time, often on the supposed basis of a low glycaemic index. However, much more research is needed to demonstrate such benefits for individual products.
Ingredients in agave of much current interest are the fructans, which are non-digestible polymers of fructose, the sugar found in honey and ripe fruits. Fructans escape the action of digestive enzymes and reach the large bowel where they serve as fermentative substrates to the colonic bacteria.
Research from Mexico, the country where agave chiefly grows, has shown that these compounds may have potential as carriers of drugs to the colon (because they are resistant to acid degradation in the stomach) as well as stimulating the growth of healthy bacteria in the large bowel.
Such prebiotic activity has been linked with improved immunity and reduced risk of various diseases, such as constipation, diabetes and colon cancer.
Although fructans are found in several plants, such as artichoke, garlic, onions and chicory, agave is one of the few plant sources that contains fructans in large amounts. When ripe, the plant contains 80 per cent fructans by weight.
Researchers at the University of Guadalajara have extracted fructans from blue agave, modified them and made them into micro-spheres to encapsulate drugs such as ibuprofen. In preliminary laboratory tests, ibuprofen-filled microspheres exposed to hydrochloric acid for an hour appeared to remain physically intact, findings which the researchers are taking forward in further studies on animals.
However, it is the potential prebiotic effects of agave fructans that were the focus of research presented at a meeting of the American Chemical Society earlier this year. Previous work has shown that fructans from sources other than agave can stimulate the growth of healthy bacteria in the large bowel as well as the production of such short chain fatty acids as butyric acid. These effects improve the absorption of minerals, particularly calcium and magnesium, both of which can be absorbed from the colon. In this latest study, researchers from the Guanajuato found that mice fed agave fructans absorbed more calcium from their food and eliminated less calcium in their faeces, suggesting that agave fructans may have a role in maintaining healthy bone.
Findings from another research group in Mexico, published in the British Journal of Nutrition in 2008, suggest that agave fructans may also help to regulate appetite and metabolism of lipids and glucose by promoting the secretion of glucagon-like peptide-1 (GLP-1), a satiety hormone. In this research, mice fed agave fructans had lower body weight gain and food intake than mice fed a control diet. Serum glucose and cholesterol were lower in the mice fed fructans from both agave and another food source, but only agave fructans induced a higher concentration of GLP-1, indicating that the source of the fructans may be important for producing these promising effects.
If these benefits are confirmed in further research, it is important to note that they cannot be obtained from tequila because fructans are converted into alcohol when blue agave is used to make it.