I've been reading that ingesting high quantities of fructose isn't great for you. fructose, the sugar in fruits, isn't available to be used by the body until it's broken down by the liver first so too much fructose in the diet can be hard on your liver, whereas glucose is easily absorbed into the bloodstream (broken down by digestive enzymes from starches i.e. cooked rice). This is why fructose doesn't trigger blood sugar spikes.
Also studies comparing fructose and glucose show fructose cause more health problems. Of course the subjects were probably not vegetarian/vegan but I do wonder about the long term effects on the liver?