The original poster's question was in regards to McDonalds and it's possible effect on UC. It is going off on a tangent to be up on the soapbox regarding fast food being healthy or unhealthy. In most cases that doesn't have anything to do with it's effect on a particular person's UC. There's not many people that would disagree with fast food being unhealthy, especially if done in excess. I know I can honestly say that my UC would be better if I ate McDonalds every single day than if I ate a lot of vegetables, fruits, and fiber every day. That sucks but that's just the way it is with many of us. Even though that is the case I limit my fast food and eat limited amounts of vegetables, fruits, and fiber anyway.
In my opinion health nuts are barking up the wrong tree when they try claiming that a healthy diet is the cure for all ills. Many people came down with UC after switching from an unhealthy diet to a healthy one. There is a lot of evidence that a bad diet can be a factor in bringing on all kinds of diseases but there is basically no evidence that changing from an unhealthy diet to a healthy one will cure you of a disease you already have (except for maybe Diabetes).
Sodas don't seem to bother me at all because I did a lot of personal testing on myself and found that just drinking water and nothing else for weeks didn't change my condition one bit, but, a lot of people do have UC problems with sodas, caffine, sugar, and artificial sweeteners and sodas are published in many places as not being good for UC'rs.