Herbert Shelton pretty much set the food combining standards, which my book The Raw Gourmet describes. In fact my book even has a symbol next to each recipe that is properly food combined. That being said, with food, as I am sure you know-there aren't too many "rules"- as we are each so different. Personally I don't combine protein and carbohydrates in one meal, unless it is a really small amount like 100 calories or so. The rest isn't as important to me. The green smoothie rage is a huge success and I feel that the use of greens in with fruit mitigates the effects of fruit sugar on the body for those who are concerned about that. I would NOT regularly use pineapple as it is quite acid forming-yes pineapples contain bromelain, which is one type of digestive enzyme, but they are acid forming. So much for rules. If I had to worry about sweet fruits and acid fruits and sub acid fruits every time I ate I would be afraid to eat. People with delicate digestion or people who are very ill and need to eat absolutely optimally are good candidates for learning these rules or leaving a chart up on the wall to refer to, but once health is restored I do not see it as a big problem. Dr. Gabriel Cousens states that all these food combining principles are more important to use with cooked food but not really with raw, and I definitely find that to be true and felt so long before he officially came out with that information.