So you made an interesting suggestion that I want to talk about. You suggested that you simply substitute Maple Syrup or Agave for sugar in Ketchup and that would make it healthier.
Sugar is toxic. All types of sugar, from a cane or a beet or a tree or a plant are exactly the same. There is no good sugar. In fact the High Fructose Corn Syrup industry has spent millions of dollars on commercials that tell you HFCS is exactly the same as table sugar.. Agreed. It is . They are both toxic in the amounts found it our current diets.
All sugar spikes insulin. The theory is that this constantly high level of insulin most people have is the central villain in obesity and other related illnesses.
When sugar appears in nature it is always wrapped around lot of fiber. When sugar is consumed along with lots of fiber it does not enter the blood stream as fast and you dont get the immediate mega hit of insulin. Sugar cane is a great example. Its a woody stalk and would take you days to get to the sweetness by chewing on it.
Also, we have evolved to recognize sweetness in food as a signal that a food is not poisonous. Nothing is nature that tastes sweet is poisonous to humans. Therefore, we have evolved to recognize sweet things as good (edible). It sets off bells in our brain and nervous system that are pleasurable. Sugar hits the same pleasure spot in the brain as cocaine. If you dont beleive it, try stopping. You will go through symptoms of withdraw.
Here is a lecture by Dr. Robert Lustig (not a Dentist, he is an endocrinologist
, "Sugar, the Bitter Truth" His book by the same name will be out shortly. He is the best known researcher on the topic. This lecture is meant for laypeople. He's a good speaker