Before blooming, the agave plant stores a large amount of sap in its body. This sap is collected and filtered, and then heated. After heating, the sap is mixed with enzymes that convert its natural inulin content into sugar, giving the agave nectar its sweet taste.
Agave nectar is low on the glycemic index, meaning it spikes blood sugar less when it is ingested opposed to other sweeteners. It still has the same number of calories as regular cane sugar, but it has a sweeter flavor, so less of the agave nectar can be used to sweeten foods and beverages.
Some species of agave plants, including the species that agave nectar is harvested from, can contain a type of natural plant steroid that can be dangerous to pregnant women because it can cause miscarriages. According to Dr. Andrew Weil, this is a low risk because of the small amount of agave nectar that is usually used in foods.
Many people on raw food diets choose not to eat food that has been heated above a certain temperature. Agave nectar is often labeled with the word "raw" on the label, when it is actually processed at temperatures around 160 degrees Fahrenheit. This is much too hot for a raw diet, and people on a raw diet may be confused by this labeling.