Acid and Alkaline. Direct neautralisation or by reaction?

Just one queery...I am going to give the alkaline thing a shot but I want to know about how it neutralises. One person has written that he drinks bi carb of soda to neautralise the acid in his stomach. However, the foods that I've seen are alkalising are acidic. Am I right in thinking that by eating acidy foods, the body produces less acid and so a balance is found or is the neutralisation as straight forward as pouring alkali on acid. Is is different in the stomach to the rest of the body?
I hope you can answer my question, I'm currently suffering quite badly with UC.