My wife has an undiagnosed digestive problem with beef, along with a bunch of other unknown things. For some reason, certain foods (such as kidney beans) give her enough stomach pain that we usually end up in the ER. We have seen every GI doctor in southern Colorado and after 6 years of testing and poking and prodding, they all end up just saying she has Irritable Bowel Syndrome, but that is really just a blanket diagnosis for "we don't have a f*cking clue". She has tried gluten free diets, she has avoided certain types of foods and we have systematically eliminated a few foods from her diet (such as beef, most red beans, and a lot of processed foods) but we still don't have it perfect.
For a while she was basically vegetarian, it that didn't solve the problem. Now, she eats lots of fish, chicken, pork, and eggs to get protein, with a lot of salads and fresh veggies. To date, we can't correlate any fresh vegetables as causing her problems, it's always processed foods or beef products.
Yes, this has totally changed how I eat and how we prepare meals.

