What's the deal with agave nectar?

It seems that agave nectar is the new darling of the sweetener market, cropping up in everything from cocktails to smoothies to snack foods. Last week, I was at a bar and ordered my favorite drink- a caipirinha- and asked the bartender to use very little simple syrup. He obliged, but later suggested I try the drink with agave nectar instead of simple syrup. He said that not only does it complement the flavor of the rum in the drink, but it is also all-natural. I gave him the skeptical look I give anyone who tries to "sell" me on a health food, but said I'd consider it. No use wasting my happy hour debating nutrition with someone who probably didn't know the difference between a monosaccharide and a polysaccharide.

But his suggestion, along with the increasing ubiquity of agave nectar and an inquiry from a facebook friend, has prompted me to look further into the health claims surrounding this product. Agave nectar, or agave syrup, is a sweetener that is made by filtering and heating the juice from agave plants. Thus, although it is natural, it is not entirely unprocessed. The syrup is comprised primarily of fructose (84%). Like table sugar (sucrose), agave nectar has 16 calories per teaspoon, but because it is sweeter than sugar, less of it may be needed to achieve the same level of sweetness. This, I would argue, is one possible benefit of agave nectar. The other is one of its most touted characteristics: its low glycemic index (GI), which is between 20 and 30 on a scale of 1-100. Foods with low GIs do not elicit as great a rise in blood sugar as foods with higher GIs. Therefore, if agave nectar has a lower GI than other sweeteners (honey's GI is 55 and table sugar's is 68), then it would make sense to think that it would be preferable, especially for people with diabetes or glucose intolerance.

To investigate whether the purported benefits of agave nectar are supported by scientific studies, I logged on to PubMed to do an initial search, using only "agave nectar" as my search term. Given that agave nectar is becoming so widespread in grocery stores and restaurants, I expected to get loads of results that I would have to narrow down with more refined searches. Imagine my surprise when this search returned only 9 results, none of which had anything to do with the effects of agave nectar consumption on the human body. In light of the dearth of research on the topic, my opinion on it must necessarily be based solely on deductive reasoning.

So, we don't know exactly what impact agave nectar has on human metabolism. We do, however, know a little about the impact of its component sugars--primarily fructose, and to a lesser extent glucose and sucrose. I had mentioned that agave nectar is 84% fructose. Glucose and sucrose represent approximately 8% each. In comparison, table sugar is 50% fructose and 50% glucose. The much-demonized high-fructose corn syrup typically contains 55% fructose and 45% glucose. Honey has similar ratios: 50% fructose, 44% glucose, 1% sucrose.

There is some evidence to suggest that pure fructose may have some adverse metabolic effects; namely, increasing the amount of hazardous abdominal fat, and raising blood triglyceride levels. This is because fructose is metabolized differently from glucose and in a way that may encourage the liver to produce fat in the form of triglycerides and release them into the bloodstream. The other side of this coin is that fructose doesn't increase blood glucose levels the way glucose does. So, we have something of a paradox in fructose: it doesn't raise blood sugar (Good), but it may promote fat storage and high triglycerides (Bad). Because agave nectar contains a higher proportion of fructose than most, if not all, other sweeteners on the market, the concerns about fructose could reasonably apply to agave nectar as well.

So, as to the benefit of agave nectar's low glycemic index, I would say this is a wash. It does in fact have a low GI, but the other possible negative effects of fructose may very well negate this positive quality. As to the other possible benefit of agave nectar- that it is sweeter than sugar and can be used in smaller quantities- I cannot make a conclusion. Unless and until there are studies that demonstrate that people actually use less agave nectar than they would sugar, and therefore consume fewer empty calories, I remain unconvinced. My guess is that people are more likely to misconstrue the healthy halo around agave nectar as license to use it with reckless abandon. But this, of course, is just a hypothesis.

The bottom line on agave nectar, as I see it, is the same as it is for all other forms of sugar: it provides no nutritional benefit other than calories and is still essentially sugar, albeit much more expensive sugar! If you like the flavor of it, or if you find that you can replace larger amounts of table sugar with smaller amounts of agave nectar, then by  means use it. It's probably not going to hurt you. But you should not be fooled into thinking that it is a health food.

References
Leibman B. Sugar overload: Curbing America's sweet tooth. Nutrition Action Health Letter. January/February 2010.
Agave nectar is in demand, but is it better for you than ordinary sugar? Environmental Nutrition. April 2010.