Agave nectar (more accurately called agave syrup, as "nectar" is a marketing term) is a sweetener commercially produced from several species of agave, including Agave tequilana (blue agave) and Agave salmiana. Agave syrup is sweeter than honey and tends to be less viscous. Most agave syrup comes from Mexico and South Africa.
Agave syrup has been marketed as a "healthy" sweetener, but this fact has been the subject of criticism due to its very high fructose content (which is even more than high fructose corn syrup in its fructose content by weight) and its potential to lead to insulin resistance and significantly increased triglyceride levels (a risk factor for heart disease). 
To produce agave syrup from the Agave americana and A. tequilana plants, the leaves are cut off the plant after it has aged seven to fourteen years. The juice is then extracted from the core of the agave, called the piña. The juice is filtered, then heated to break the complex components (the polysaccharides) into simple sugars.[Need to cite reference for production process] The main polysaccharide is called inulin or fructosan and is mostly fructose. This filtered juice is then concentrated to a syrupy liquid, slightly thinner than honey. Its color varies from light- to dark-amber, depending on the degree of processing.
Agave salmiana is processed differently from Agave tequiliana. As the plant develops, it starts to grow a stalk called a quiote. The stalk is cut off before it fully grows, creating a hole in the center of the plant that fills with a liquid called aguamiel. The liquid is collected daily. The complex components of this liquid are broken down into fructose and glucose.
An alternative method used to process the agave juice without heat is described in a United States patent for a process that uses enzymes derived from the mold Aspergillus niger to convert the inulin-rich extract into fructose. Aspergillus niger, a fungus commonly used in industrial fermentations, is "generally recognized as safe" (GRAS) by the U.S. Food and Drug Administration.
Agave nectar consists primarily of fructose and glucose. One source gives 47% fructose and 16% glucose; another gives 56% fructose and 20% glucose. These differences probably reflect variation from one vendor of agave nectar to another.
The impact of agave syrup on blood sugar (as measured by its glycemic index and glycemic load) is comparable to fructose, which has a much lower glycemic index and glycemic load than table sugar (sucrose). However, consumption of large amounts of fructose can be deleterious and can trigger fructose malabsorption, metabolic syndrome, hypertriglyceridemia, decreased glucose tolerance, hyperinsulinemia, and accelerated uric acid formation.
Agave syrup is 1.4 to 1.6 times sweeter than sugar and is often substituted for sugar or honey in recipes. In cooking, it is commonly used as a vegan alternative to honey for those who choose to exclude animal products from their diets. Agave syrup dissolves quickly and so it can be used as a sweetener for cold beverages such as iced tea. It is added to some breakfast cereals as a binding agent.
Agave syrups are sold in light, amber, dark, and raw varieties. Light agave syrup has a mild, almost neutral flavor, and is therefore sometimes used in delicate-tasting dishes and beverages. Amber agave syrup has a medium-intensity caramel flavor and is therefore used in dishes and drinks with stronger flavors. Dark agave syrup has stronger caramel notes and imparts a distinct flavor to dishes, such as some desserts, poultry, meat, and seafood dishes. Both amber and dark agave syrups are sometimes used "straight out of the bottle" as a topping for pancakes, waffles, and French toast. The dark version is unfiltered and therefore contains a higher concentration of the agave plant's minerals. Raw agave syrup also has a mild, neutral taste.[dubious ] It is produced at temperatures below 118 °F (48 °C) to protect the natural enzymes, so this variety could be considered an appropriate sweetener for raw foodists.
Potential Health Risks of Agave Syrup
Commercial agave syrups have received criticism from medical experts for their high fructose content. The fructose content of commercial agave syrups has been measured at between 59 and 90 percent, which is even more than high fructose corn syrup in its fructose content by weight (HFCS, by comparison averages 55% fructose content). 
Also due to its high fructose levels, agave syrup has the potential to drive up uric acid levels. According to Dr. Joseph Mercola, "the connection between fructose, uric acid, hypertension, insulin resistance/diabetes and kidney disease is so clear that your uric acid level can be used as a marker for toxicity from fructose." 
- Hocman, Karen (August 2009). "Agave Nectar a.k.a. Agave Syrup". The Nibble.
- Gary M. Mohr, Jr. (3 Oct 1999). "Blue Agave and Its Importance in the Tequila Industry". Ethnobotanical Leaflets. Retrieved 2010-01-04.
- Dr. Jonny Bowden (15 Feb 2010). "Debunking the Blue Agave Myth". HuffingtonPost.com. Retrieved 2014-01-06.
- "Monocarpic Behavior in Agaves". J. C. Raulston Arboretum, North Carolina State University. June 19, 2009. Retrieved 2010-01-04.
- "Method of producing fructose syrup from agave plants (United States Patent 5846333)". 1998-12-08.
- Onions, A.H.S., Allsopp D., Eggins H.O.W. (1991). Smith's Introduction to industrial mycology. (7th ed. ed.). Cambridge, UK: Cambridge University Press. ISBN 9780521427821.
- "Inventory of GRAS Notices: Summary of all GRAS Notices". US FDA/CFSAN. 2008-10-22. Archived from the original on 11 October 2008. Retrieved 2008-10-31.
- "Volcanic Nectar Blue Agave" Global Goods Inc. (Retrieved 2013)
- Ralf Patzold and Hans Bruckner (2005). "Mass Spectrometric Detection and Formation of D-Amino Acids in Processed Plant Saps, Syrups, and Fruit Juice Concentrates". J. Agric. Food Chem 53 (25): 9722–9729. doi:10.1021/jf051433u. Retrieved 2 November 2010.
- "Agave Nectar and the Glycemic Index". All About Agave. Archived from the original on 17 September 2010. Retrieved 2010-10-03.
- "Agave Nectar vs. Liquid Sugars". All About Agave. Archived from the original on 17 September 2010. Retrieved 2010-10-03.
- "Agave Nectar vs. Granular Sugars". All About Agave. Archived from the original on 17 September 2010. Retrieved 2010-10-03.
- David Mendosa. Revised International Table of Glycemic Index (GI) and Glycemic Load (GL) Values—2002. Archived from the original on 10 November 2010. Retrieved 2 November 2010.
- Basciano H, Federico L, Adeli K (2005). "Fructose, insulin resistance, and metabolic dyslipidemia". Nutrition & Metabolism 2 (5). doi:10.1186/1743-7075-2-5. PMC 552336. PMID 15723702.
- Mayes, PA (Nov 1993). "Intermediary metabolism of fructose". Am J Clin Nutr. 58 (5 Suppl): 754S–765S. PMID 8213607.
- Buemann B, Toubro S, Holst JJ, Rehfeld JF, Bibby BM, Astrup A (Aug 2000). "D-tagatose, a stereoisomer of D-fructose, increases blood uric acid concentration". Metabolism 49 (8): 969–76. doi:10.1053/meta.2000.7724. PMID 8213607.
- Davis, W (December 6, 2008). "Yet another reason to avoid fructose". The Heart Scan Blog. Archived from the original on 10 October 2010. Retrieved 2 November 2010.
- Johannes, Laura (October 27, 2009). "Looking at Health Claims of Agave Nectar". The Wall Street Journal. Archived from the original on 2 January 2010. Retrieved 2010-01-04.
- "Agave Nectar Recipes," Global Goods Inc and Cook'n With Agave♙
- "Vegan Sugar Substitutes". LiveStrong.com. Archived from the original on 13 October 2010. Retrieved 2010-10-03.
- Chomka, Stefan (30 July 2007). "Dorset Cereals". The Grocer (Crawley, England: William Reed Business Media). Retrieved 16 January 2011.
- Getty, Anna (2010). Anna Getty's Easy Green Organic. Dan Goldberg and Ron Hamad, photographs. San Francisco: Chronicle Books. p. 141. ISBN 0-8118-6668-8. Retrieved 25 November 2011.
- Ania Catalano. Baking With Agave Nectar: Over 100 Recipes Using Nature's Ultimate Sweetener, 2008, Celestial Arts, p. ix.
- Dr. Joseph Mercola (3 Jul 2010). "Can Agave Syrup Spike Uric Acid Into the Danger Zone". Mercola.com. Retrieved 2014-01-06.
- Mancilla-Margalli, Norma A.; Mercedes G. López (13 February 2002). "Generation of Maillard Compounds from Inulin During the Thermal Processing of Agave tequilana Weber Var. azul". Journal of Agricultural and Food Chemistry 50 (4): 806–812. doi:10.1021/jf0110295. Retrieved 25 November 2011.
- "Formal Agave Health Benefits". Retrieved 4 April 2012.