Ayurvedic recommendations on food combinations.
This is a recommendation based on foods that don't mix well and are difficult to digest when mixed.
Some constitution will be able to digest better than other. Occasionally it might be okay to do a "wrong" mix but on a regular basis it will create "ama" or metabolic toxins as a result of undigested foods. Observe your tongue in the morning and if you have a thick coating it is a sign of ama.