Food is digested in two stages. The first stage involves the bolus (where the concentration of enzymes is low) as it moves along the alimentary tract. At this stage, the food is subjected to primary treatment, the boluses are first broken down into smaller ones and these in turn become separate molecules.

The main process of digestion (the breakdown of molecules) occurs at the second stage when digestion takes place in the intestine near the intestinal wall. This type of digestion, called parietal digestion, is very good for the organism. The first advantage, which has already been mentioned, is that it is possible to attain a very high rate of digestion with only small amounts of enzymes. The other advantage is that the digestive enzymes can be used sparingly. The enzymes that are adsorbed on the intestinal wall are preserved and continue to serve the organism for a long time, while those from the bolus are eliminated together with the remains of the undigested food and are thus lost. The third and final advantage is that the completely digested food, which is ready to be absorbed by the blood, appears to be just where absorption takes place, i. e. close to the intestinal wall. This greatly accelerates and improves absorption.

This discovery allowed another mystery to be solved. Physicians have long been aware that sometimes in some humans the alimentary glands almost stop function as a result of illness. The sick person does not notice this since it almost does not aftect his digestion. How the food was digested remained a puzzle. Now it has been discovered that the negligible amounts of enzymes secreted by a faulty gland are adsorbed by the intestinal wall, accumulated and retained, thus ensuring the normal digestion of food.

On the spur of the moment many of us would want to go on a diet in order to stay healthy and fit.

However, it is necessary to emphasize that you should know the objective of your diet management which might include one or all of the following:

  • If you are diabetic, you need to control the levels of glucose in blood and prevent loss of glucose in urine.
  • Achievement of  a satisfactory weight. Overweight is indeed a health hazard particularly for diabetics. If you are under-weight, you will need to increase your body weight.
  • Provision of a palatable diet which is acceptable to each individual.
  • Getting sufficient calories for normal activities.

Once the objectives are clear, the next step is to:

  • Develop the diet plan relative to each person depending on his/her age, weight, height and activity. The planned diet should take into account the individual’s economic status, availability and cost of food items, national, religious and social customs, personal idiosyncrasies, occupation, facilities for preparing and obtaining meals and so on.
  • Define whether the person is diabetic or not.
  • Determine the nutritional requirements of the person.

Unfortunately, we still see people eating the same food over and over again. They simply resist changing their nutritional habits for their benefit.

However, it is important to understand the following : “ Eating well, while eating right; Eating right is half the fight!”

What it means here is that you can have a free choice for possible substitutions in your diet instead of  sticking to the same program. Just make sure you meet your objectives.

Cholesterol has mistakenly been shown the main villain in heart disease whereas the fact is that one type is good for you!

In fact:

  • Studies show that foods high in cholesterol don’t raise the cholesterol level
  • An increase of the good type of cholesterol – HDL – is good for your heart
  • A diet high in vegetables and soy can lead to a reduction in cholesterol level
  • Niacin (vitamin B3) supplements can also lower the bad cholesterol level

The hype about cholesterol started after a scientist found that rabbits developed heart disease after being fed cholesterol. He didn’t realize that because rabbits are vegetarians they have no means of dealing with animal fat.

Recent controlled tests have shown that an increase in the consumption of shrimps and eggs, which are high in cholesterol, do not lead to an increase in levels.

However, this doesn’t mean you can go out and binge on cholesterol. The problem is that foods high in cholesterol are mostly high in saturated fats, which most definitely are bad for hearts and arteries.

A complication with cholesterol is that there are two types: HDL cholesterol (high density lipoprotein) and LDL cholesterol (low density lipoprotein).

If you have a high cholesterol level, and much of it is LDL cholesterol, you’re at high risk for heart disease. A relatively high level of HDL usually means low risk. If your HDL makes up one-fifth of your amount of cholesterol you have average risk of heart disease – this is a ratio of cholesterol to HDL of 5:1. With only one-eighth of HDL you’re at high risk. If HDL accounts for one-third you’re low risk (3:1).

However, having a very small amount of cholesterol in your body is not good news either! People with low levels have been found to lead to strokes and to cause anti-social behavior.

How do you lower a high level of cholesterol? A recent report showed that a diet high in soy products, beans and vegetables, and without meat or fish could lower the level as much as some medications.

Nutritional supplements lower cholesterol levels. Also, recent studies show that taking fairly large amounts of niacin (B3) can have more effect than the cholesterol-lowering drugs gemfribrozil and lovastatin in reducingl levels. They do this by increasing the HDL level, while reducing total cholesterol levels.

However, if you take 500-1,500mg niacin, which you need to reduce cholesterol levels,  you may find that you get flushed uncomfortably. You can overcome this by taking the supplement in smaller doses three times a day, or by taking ‘no-flush niacin’.

So, if you are at risk with high cholesterol make sure that it is LDL cholesterol that is relatively high, and take a niacin supplement. Of course, never abandon medications without the advice of a doctor. Niacin and cholesterol-lowering drugs have been found to work well together.

Biotin is an important vitamin for proper digestion. It affects processing of most food. Biotin works with some other B vitamins to carry out essential functions, and is part of the vitamin B family, all of which are important to health. It is soluble in water, so you need some every day.

Biotin affects the processing of protein, fats and carbohydrates – that’s almost all of your main foodstuffs. For example, these processes include building amino acids into protein, getting energy from glucose. It also helps convert folic acid (folacin) into its active form so that it can do its work!

Severe deficiency of biotin is fairly rare, but various factors can prevent proper absorption of biotin. Infants can develop deficiency in biotin, however. In adults, antibiotics can result in deficiency of biotin, and some other vitamins.

Another cause of deficiency is the consumption of raw egg white in foods such as chocolate mousse. Biotin is not affected by cooked eggs. One reason that severe deficiency of biotin is rare is that the some biotin is synthesised in the intestine.

Although severe deficiency is rare, many Americans don’t get enough biotin to maintain good health, and a supplement should contain at least 50 mcg, and 100-200 mcg biotin is better. In fact, the majority of people don’t get enough vitamins, particularly B vitamins to maintain good health.

To get the benefits of biotin and enjoy life more, you can take either a vitamin B complex supplement, or better a multi-vitamin-mineral supplement which contains all B vitamins.

An experiment was carried out. A piece of intestine was placed for some time in a test tube containing a starch solution. The idea was that if the intestine contained digestion-accelerating substances, they would be secreted into the test tube. The intestine was then removed and some amylase added to the starch. Digestion proceeded slowly, just as in the original experiments.

Perhaps the piece of intestine did not have enough time to secrete the substance it was supposed to have. Yet another experiment was carried out. An extract was obtained from the intestine of a slaughtered animal. The extract should, no doubt, have contained the required substance.

However, when the extract was added to the test tube containing the starch and amylase, it did not accelerate the rate of digestion. This meant that the intestinal wall did not contain substances accelerating the process of digestion. What then triggered off the process?

The puzzle was solved unexpectedly. It was the very structure of the intestinal wall that facilitated the process of digestion. The surface of the epithelial cells lining the intestine carries ultra-microscopic shoots. Each cell carries as many as three thousand shoots, and this makes the surface area of the intestine very extensive, enabling it to adsorb, i. e. precipitate and retain, a great many enzymes. These enzymes act as catalysts accelerating chemical reactions. The enzymes interact chemically with the reagents, but as soon as the reaction is complete, they regain their previous chemical composition. This explains why even small amounts of catalysts markedly accelerate the rate of chemical reactions.

It is only natural that digestion is more energetic on the surface of the intestinal wall where the concentration of enzymes is much greater than within the mass of food. The total amount of enzymes may not be large; they can be used again and again. What is important is their extremely high concentration and this is why even moderate amounts of enzymes ensure a high rate of digestion.

It was not easy to study the process of digestion. It was as late as the turn of the last century that the Russian scientist Ivan Petrovich Pavlov completed a detailed study of the main alimentary glands. They turned out to be numerous and, what is more, it was discovered that for each type of food they produce a special composition of digestive juices. Academician Pavlov was awarded the Nobel prize, the highest international award, for these investigations. Thus, the basic mystery surrounding the process of digestion seemed to have been unveiled. However, the discovery was not yet complete. Nobody could reproduce the entire process of digestion in the laboratory by pouring into a test tube the necessary digestive juices in the correct sequence, and thus imitating the process observed in living organisms under natural conditions. The food was also digested in the test tube, but the process was all too slow, much slower than in the alimentary tract.

Recently, scientists have succeeded in uncovering this mystery. An astonishing thing is that the food which comes into contact with the intestinal wall is digested much more quickly than that incorporated in the main mass of food. This is similar to what happens when food is fried in a pan: the food in immediate contact with the walls of the pan cooks much more quickly. This is quite under­standable, for the pan is much hotter than the food. But the intestinal wall is not at all hot, so why then does it accelerate digestion?

The first thing was to find out whether the intestinal wall ready accelerated digestion. With this in view, the following experiment was carried out. A piece of intestine from a freshly killed animal was placed in one of two test tubes containing equal amounts of a mixture of starch and an amylase (a starch-splitting enzyme). Splitting of the starch proceeded much more rapidly around the piece of intestine which proved that the intestinal wall did accelerate digestion. But how does this happen?

Even primitive people knew that the food eaten by man and animals is digested in their stomachs. When skinning their game, they were sure to peep into the stomachs. Even nowadays almost no housewife can resist the tempta­tion of learning what the pike had for dinner and whether the chicken’s stomachs contain anything of interest besides small stones and sand. When hunters cut up their prey, they found in the stomachs and intestine neither meat, nor grass or seeds, but a pasty mass, as though the food had been cooked there.

It took man a long time to find out what really occurs. The food is not changed under the influence of heat: the temperature in the stomachs of even the ‘hottest’ warm­blooded animals is no higher than 38-43°C and this is not sufficient to cook food. Digestion takes place with the aid of digestive juices containing special enzymes.

The alimentary tract of man and animals is a complex chemical laboratory. The food consumed is ground, mixed with various digestive juices and moves gradually from one part to another. In each part the food is held long enough for it to be digested, being saturated with special substances. These substances are absorbed during the digestive process, that is, during the breakdown of complex chemical substances into simple ones (proteins into amino acids, fats into glycerol and fatty acids, carbohydrates into monosaccharides). What cannot be digested and used by the organism is disposed of.