This occurs because larger food particles are not broken down properly into their smaller constituents that allow for normal absorption through the digestive tract and healthy elimination. (pethealthandnutritioncenter.com)
From a biomedical point of view; digestion is breaking large food particles into smaller ones; this is catabolism. (consumerhealthdigest.com)
When the gut is leaky, undigested large food particles leak through the intestinal wall, prompting a response from the immune system, which can create many food allergies that would otherwise not affect you. (myersdetox.com)