While we're all for defending the nutritional value of artisanal syrups, which, after all, are the concentrated "blood" of a tree, overly focusing on nutrition will not necessarily improve the value of your dining experience.  In his latest book In Defense of Food , author Michael Pollan offers a humorous yet piercing assessment of "nutritionalism," the newest trend in our food system that focuses on the foods we eat largely in terms of the nutrients they provide. Consider, he asks, how much of the daily news would disappear without the latest stories on fiber and fat!
Having said this, we're still fascinated by the living chemistry of food and agriculture. Here are some of the details on maple syrups that we've gathered to date.  The Maple Syrup Producer's manual offers more detail on the chemistry of maple.

Maple syrups contain natural minerals, including calcium, potassium, manganese, and zinc, and proteins, amino acids and trace vitamins (such as Niacin, B5, B2). Maple is 73 calories per ounce, with 17 g, of sugar and a glycemic load of 11, compared to white sugar at 108 calories per ounce, 28 g. of sugar and a glycemic load of 19, and honey at 85 calories per ounce, 23 g. of sugar with a load of 14.  

Recent research in maple has revealed that maple syrup has many beneficial compounds.  Several of these are known for their anti-inflammatory, anti-cancer, and antioxidant properties.  
Of great interest to scientists is the discovery in maple sap and syrup of abscisic acid, a phytohormone (plant hormone) which is known to stimulate insulin release through pancreatic cells to increase sensitivity of fat cells to insulin.   Researchers caution that further studies are needed to understand exactly how eating maple affects insulin behavior.

Nutrition Facts