A few practical corollary consequences of combination of foods that follow naturally in day to day life are highlighted below:
STARCH & SUGAR: Bread (starch) and butter (fat) is a perfectly compatible combination, but when we spread a spoonful of jam (sugar) over it, we introduce sugars to the blend, which interferes with the digestion of the starch in bread. It has been established that, when sugar enters the mouth along with starch, the saliva secreted during chewing food will have no ptyalin, thereby hinder normal starch digestion before it reaches the stomach. Furthermore, such masticated combination of sugar held in the stomach until the starch is digested, causing it to ferment. The by-products of sugar fermentation are highly acidic, which in turn further inhibits digestion of starches, which require alkaline mediums for digestion. The same principle applies to breakfast cereal corn flakes sprinkled with sugar, heavily frosted cakes, sweet pies, and so forth.
PROTEIN & STARCH: Though this is the worst possible combination of foods to mix together at a single meal as we found above, yet it is the mainstay of our modern diets: meat and chapatti-Nan, Meat and fried-boiled rice, meat and potatoes, sea-foods and rice, hamburgers and fries, eggs and toast, Bread- Omelet etc. When we consumes protein and starch together, the alkaline enzyme ptyalin pours into the food as it's masticated and when reaches the stomach, digestion of starch by alkaline enzymes continuing at full strength unabated, thereby preventing the digestion of protein by pepsin and other acid secretions.
PROTEIN & PROTEIN: Different proteins have different digestive requirements. For example the strongest enzymatic action on milk occurs during the last hour of digestion, whereas on meat it occurs during the first hour and on eggs somewhere in between. It is instructive to recall the ancient dietary law commanding against the simultaneous consumption of milk and flesh.
ACID & STARCH: Any acid taken together with starch suspends secretion of ptyalin, a biochemical fact of life upon which all physicians agree. Therefore, when we consume oranges, lemons and other acid fruits, or acids such as vinegar's, along with starch, no ptyalin is secreted in the mouth to initiate the first stage of digestion. Consequently, the starch reaches the stomach without the vital alkaline juices it needs to digest properly, allowing bacteria to ferment it instead. A single teaspoon of vinegar, or its equivalent in other acids, is all it takes entirely to suspend salivary digestion of starch in the mouth. Thus tomatoes should not be eaten with starches especially potatoes rice or bread.
ACID & PROTEIN: Since protein requires an acid medium for proper digestion, you'd think that acid foods would facilitate protein digestion, but that's also not the case. When acid foods enter the stomach they inhibit the secretion of hydrochloric acid, and the protein-digesting enzyme pepsin can work only in the presence of hydrochloric acid, not just any acid. Therefore orange juice inhibits the proper digestion of eggs, and a strong vinegar dressing on salads inhibits the digestion of steak.
MELONS: Melons are such a precious food for humans as they require no digestion whatsoever in the stomach. Instead, they pass quickly through the stomach and move directly to the small intestine for digestion and assimilation. But this can be possible only when the stomach is empty and melons are taken alone, or in combination only with other fresh sweet raw fruits. When consumed with or after other foods that require complex digestion in the stomach, melons cannot pass into the small intestine until the digestion of other foods in the stomach is over. So they remain and stagnate instead, quickly fermenting and causing all sorts of gastric distress.
DESSERTS: We should avoid any sort of sweet dessert after a big meal, for this type of food combines poorly with everything. Even fresh fruit should be avoided right after a big meal because it will back up in the stomach and ferment instead of digest. If you really have a 'sweet tooth' and crave cakes, pies and pastries, indulge your habit occasionally by making a whole meal of them. They are still not good for you but at least taken alone they will not cause as much gastric distress and toxic by-products as when taken after meals.
MILK & DIARY: If we look at nature, we see that all the young after birth feed exclusively on milk until weaned away from it and start to have other foods. The milk-digesting enzyme lactase naturally disappears from the human system upon reaching maturity. This paves the way to prove that adult humans have no more nutritional need for milk. Though milk is a complete protein food when consumed raw, it also contains fat, which establish that it combines poorly with any other food except itself. Upon entering the stomach, it curdles immediately so if there is other food present the curds coagulate around these food particles and insulate them from exposure to gastric secretions, delaying digestion long enough to cause the onset of putrefaction. Therefore, the foremost rule of milk consumption is, 'Drink it alone, or leave it alone.'
MILK & SOUR FRUITS: Though many people regard this combination as harmful in reality it is other way. Combination of milk and fruits are very good especially bitter like oranges, grapes, lemon, and tomato. To digest milk it is necessary to separate water from solid matter while entering the stomach. Acidic enzymes are needed to do the curdling and saliva doesn’t have acidic enzymes to do this. Eating sour fruits along with milk enhances the process of curdling and digesting it.
It is much important to note the fact that without complete digestion, the nutrients in even the most wholesome food cannot be fully extracted and assimilated by the body. Moreover, incomplete digestion and inefficient metabolism is the major cause of fat and cholesterol accumulation in the body. A low calorie diet of overcooked, processed and improperly combined foods will still make you fat and leave sticky deposits in your arteries, just as the wrong mix of fuels will leave carbon deposits on the spark plugs of an engine, clog the pistons, and create foul gaseous exhaust. On the other hand, if foods are properly combined for consumption, then regardless of how many calories or how much cholesterol they contain they will not make you fat or clog up your arteries, especially if at least half your daily food intake is taken raw natural fruits and salads.
An authoritative point to Keep in mind for consideration about meals is that the smaller the number of courses they consist of, the better it will be. They should approximate to a one-course meal as much as possible. Simple meals in every way are more conducive to health, than more elaborate ones, no matter how well they may be combined. Ideally, one should consume only one variety of food at a single sitting. Throw a glance at nature proves this point. Carnivorous animals never consume starchy items with their meat, but they do supplement digestion occasionally purging their bowels by chewing on wild weeds that have medicinal properties. It has also been observed by bird watchers for centuries that birds eat bugs and worms at one time of day, seeds and berries, at another, but never both together. What makes we humans think that our digestive tract is so different from all other species in nature!!!