In other words, people who eat lots of fruits, vegetables and legumes have lower rates of heart disease. But no one knows exactly why this is. Why do fiber-rich foods appear to prevent heart disease? Is it the fiber? Or is it something else in those foods? Maybe it's a combination of things. Maybe there is no single, magic bullet. And so you have to ask... If we're not sure what it is in fruits and vegetables, then, as opposed to saying, well, it's probably the fiber, or it's probably this or that, why not just have people eat lots of fruits and vegetables? Now, some food scientists are less critical of these fiber additives. They say many Americans are always going to choose junk food over fruits and vegetables. So you might as well put some fiber in there, even if we don't really know how much benefit it's having. But what pretty much everyone agrees is this: Given a choice between fiber-fortified sugar cereal and an apple, you're better off with the apple. I don't want people to think that by adding things to unhealthy foods, it somehow makes them healthy. And I think that's the most important message. One thing we do know about some synthetic fiber additives: too much of them can give you gas. But don't expect to see that mentioned on the front of your cereal box.