Most of today's researchers agree that Man is an omnivore,by nature.This is because of  the design of the digestive system,and also the preferences of all kind of tastes and flavours.The nature has been and is extensively generous with all the food that provides, and always the man has been conscious that behind this variety and abundance,some limitations are  imposed by the nature itself.  Not all kind of food requires the same way to be prepared or to be cooked. And not only this, but we also tend to forget that not all kind of food go well together.

To buy and prepare decent food in decent quantities, is not the only priority.  Each food has its "prospect", that defines how, when and even a different set of conditions:the theory of food combining.

The principle of food combining has been extensively studied by for the hygienist Herbert M.Shelton,author of the book "Food Combining Made Easy".

His research exposes the rules of proper food combining,as consequences of studies on digestive physiology,

The idea behind food combining is that different foods digest at different rates and require different digestive environments. Here are some of the basic rules,

1. Digestion time of each type of food is not the same.

2. The digestion of different types of foods occurs in different areas of the digestive tract.

3. The degree of acidity is different for the digestion of each type of food:

  The enzymes, which are some substances that transform the food during the digestion are different: each designed to help break down one type of food, excluding any another, for example:

   . Amylase is present in human saliva that catalyses the breakdown of starch into sugars, requires an alkaline environment before it begins to work.

      . The enzymes in the stomach work best in acidic conditions.

    . Pepsin  produced in the stomach, degrades food proteins into peptides,is most active in acidic environments (Ph 1,5 to 2.2) and temperature between 37°C and 42°C in humans.

  . Pancreatic lipase degrades the Lipids (fats) into fatty acids in duodenum.

 Another rule of food combining diets is that fruit should be eaten alone.

All this carries us to the following conclusions:

1. Combining proteins and starches

Is a bad combination for a good digestion.Even starch-proteins is the most common form of food in our diet.Hamburger and chips,eggs and bread,etc..

Proteins needs acidic environment. Starches needs alkaline environment,this means  When we ingest proteins and starches together neither the proteins nor the starches are absorbed well, which means we are not getting the necessary nutrients from either..

2. Acid and starch

The enzyme, ptyalin, acts only in an alkaline medium;and it is destroyed by a mild acid.

If we eat oranges, lemons or other acid fruits (or acid as the lemon or the vinegar) with a starch in the same meal, there will not be ptialina in the mouth to initiate the first phase of the digestion of the starch.  Consequently, when the starch is in  the stomach,there will be no enough alkaline juices for a correct digestion, and the bacterial fermentation is produced.

3. Acid and proteins combining

Acids interfere with the secretion of hydrochloric acid. And no acids other than hydrochloric acid activate pepsin. Therefore, Orange juice and eggs form a bad combination. Salad with vinegar and flesh is equally as bad.

4. Protein-Carbohydrate combination

The digestion of carbohydrates (starches and sugars) and of protein is so different.Carbohydrates most digestion occurs in the upper portion of the small intestine.So, when get mixed with proteins,they interfere with the digestion of each other.they cannot proceed together at all for long as the rising acidity of the stomach stops carbohydrate digestion and this is followed by fermentation.

5. Eating fruit

Fruit is digested in the intestine and not in the stomach. It is also rapidly digested (few minutes) .So,eating fruit for dessert will cause a traffic jam in the digestive tract,and make feel heavy and tired.Besides sweet foods after a meal will often cause fermentation.

The right way to eat fruits is: After a meal,leave at least three hours before you eat any fruit.or eat it a half an hour before.

Coming to the question of what about food that contain various macronutrients (Carbohydrates, proteins and lipids )at the same time. In fact, each food is a mixture of substances, and all we can say  that the food have a dominant component in proteins, in fats, or in carbohydrates.This means that a digestion of a food with a composition 100% of proteins, fats or carbohydrates,is impossible.

So,there will be a natural combining in the same food  and what happen with about the principles of food combining?

According to Shelton," the digestion of a complex food and that of a mixture of different food they are completely different.The digestive system works with a series of hormones and nervous impulses.So all the demands required for a suitable digestion of any ingested one type food are conceded..but this not possible with different types of food.

Coclusion

Combining certain foods can lead to improper digestion.But we are not asked to make a health conscious choice, if we should mix the cucumber with the yogurt, or the lettuce with the tomato.

It´s true that there's a "second brain" in our stomach.But respecting the right quantities,we can eat every type of food..But soon or later,we start to realise that following the others is not the best way,and many of our society habits are negative. and the reality that we are utterly vulnerable to the caprice of the seductive foods.However,with consciousness, we are still can accommodate our desires to a healthy and balanced diet.

Bibliography

-Food Combining Made Easy

Herbert M.Shelton

Willow publishing,Inc. San Antonio, Texas

Revised edition, 1989

-La Antidieta 

Harvey y Marilyn Diamond.

Publishing house Urano (España) 1996

- El Tao de la salud,el sexo y la larga vida

 Reid,,Daniel

Urano,Barcelona,1989