Both light and dark agave syrups contain a high amount of Fructose. Dark syrup contains a high amount of Fructans, while light syrup contains a moderate amount of Fructans. Intake is not recommended.
Agave syrup, commonly though inaccurately known as agave nectar, is a sweetener commercially produced from several species of agave, including Agave tequilana (blue agave) and Agave salmiana. Agave syrup contains 56% fructose as a sugar providing sweetening properties.
In a 100 gram (ml) reference amount, agave syrup supplies 310 calories (78 calories per tablespoon) and is a moderate source of vitamin C and several B vitamins (table). It is composed of 76% carbohydrates, 23% water, 0.4% fat, and negligible protein.
Having fructose as its primary sugar, agave syrup (56% fructose) is similar in fructose content to high-fructose corn syrup (55% fructose content), the most common sweetener used in US manufactured beverages. In a tablespoon amount (about 25 ml or grams), agave syrup supplies 78 calories, an amount similar to the value per tablespoon for high-fructose corn syrup (70 calories).
Agave syrup has a relatively high sweetness factor because it is composed of 56% fructose, having an effect on blood sugar comparable to fructose itself, as measured by its low glycemic index (GI).