Yup, it's so true! Coffee is a bitter and as such stimulates digestion. A cup of coffee before a meal can help those who need to eat more, have more appetite. After a meal, it can help get the digestion going. I know some people who have such a major digestive reaction to coffee that they can't have more than a cup or two, otherwise...there's problems.
  It's not the caffeine, it's that it is a bitter. I think most folks who drink coffee have a daily habit so they might not notice the correlation. 
 I no longer drink coffee because the caffeine gets to be too much for me. Instead, I drink tea and use 
flax seed meal.  

 There's a great, organic cold pressed flax seed meal available from Costco here in Washington.