Requirements for Proper Absorption
Although the gastro-intestinal tract is not the only way that materials have of entering our body, it is the most usual and direct route for our nutritional requirements to be satisfied. There are many criteria that have to be satisfied in order for proper absorption to occur, regularly.
Adequate amounts of nutrients
Unless adequate amounts of the body requirements are provided, then even if the absorbability is 100%, insufficient will be available for the body needs. Failure to provide this may result from a variety of causes, such as:
a) Inadequate food intake.
b) Nutritionally deficient food.
c) Poor food balance resulting in inadequate diet (fad diets, modern junk food, etc.)
Adequate enzyme activity
Unless the food is broken down into nutritionally available units, the absorption will be inadequate. For this to be accomplished, adequate enzyme activity is necessary throughout the whole of the gastro-intestinal tract – from mouth to descending colon. Any deficiency in correct enzyme production, either specific enzymes or quality, will result in incomplete digestion and, hence, absorption.
Proper functioning bowel flora
We rely upon the symbiosis (of mutual benefit) between the bacteria and other organisms that normally inhabit our colon and ourselves. Many materials produced by these bacteria, we have come to expect to be present. Without their presence in adequate amounts we are in dire peril of not surviving. Such nutrients as Vitamin K, Vitamin B12, Vitamin D, Biotin and Folic acid are among those included. These organisms, that are so crucial to our needs, are as susceptible to antibiotics as are any pathogenic bacteria, and are often far more fragile. Antibiotics are a common enough material in our diet and as treatments, in this day and age, that it makes one wonder how many of us have a fully functioning bowel flora!
Adequate amounts of water are present
We are creatures of water. So many of our internal patrol and control mechanisms cease to function with an inadequate water supply. The intestinal tract is no exception. It is imperative that adequate amounts of water are available throughout our gastro-intestinal tract. Without a gut surplus, many biochemical activities cannot be pursued and poor digestion ensues along with poor absorption.
Minimal amounts of inorganic minerals are present at any time
Most inorganic mineral salts interfere with each other’s absorption. As there is a very small segment of the ileum for absorption of these forms of minerals, there is much competition at the available sites. Absorption of inorganic, or unbound, minerals is through very specific cells that have the appropriate ligand (bonding material) in the cell to carry that mineral. Several minerals share the same cell for absorption. For instance, calcium, magnesium, iron, zinc and molybdenum all share one gastro-intestinal transport cell. Too much excess of any of these elements will block the absorption of the other minerals in that group and produce a potential malabsorption state with consequent deficiency. Therefore, megadosing of these minerals with supplements, or high intake from any other source, is contra-indicated.
The minerals are in a true state of chelation, as they occur in nature
True chelation means the mineral is bound, in some form, in a food matrix or other base material such as protein, lipid, polysaccharide or combination. This bonding, for true chelation to occur, is happening at the molecular level. Many so-called “chelates” are not. They are merely mixes of which a small percentage will bond by proximity, but insufficient to enhance the absorption rate. True chelated minerals are absorbed through the channel of their bonded substrate (the protein, lipid or polysaccharide) and, because of this, have a much greater absorption port and, hence, have improved absorbability.
Proper, patent blood supply to the intestinal tract
The blood supply to the gastro-intestinal tract must be whole and intact to allow proper assimilation of the absorbed materials into the body. Any damage to, or paucity of, blood supply, from whatever cause, will limit the effectiveness of absorption.
No “filming” of intestinal lining is present
There must be a clear route through from the intestinal lumen to the lining of the gastro-intestinal tract wall for absorption to occur unhindered. Accretions and thickened mucous accumulates on the gut wall, such as occur in many disease states and dehydration, will adversely affect absorption.
Proper presentation of food
Food must be presented in such a way that the enzymes and other breakdown activities of the gastro-intestinal tract can come to bear upon it and work. Therefore, food presentation is all-important, from taste and smell, which stimulates and informs in advance that food is on the way, to not damaging the food beyond recognition, as can occur in some processing methods and overcooking
Absence of large amounts of substances that interfere with absorption
There are many substances in food, naturally sometimes, that can interfere with the absorption processes. Such a material is phytic acid or hexaphosphate inositol. This material interferes with zinc and calcium absorption. This material is present in unrefined flours but not in refined flours. Therefore it is important to know which foods contain these materials in any quantity that will affect absorption. Leavening and cooking destroys the phytic acid to some degree.
Adequate digestion of food
This is very much linked to enzyme activity although other factors also play a part. Mastication (chewing) must be adequate for proper exposure of the food stuffs to enzymes. A reasonable stomach acidity also is essential for proper digestion, especially of liquids. Proper intestinal agitation is also necessary.
No intestinal hurry – hence value of fibre
Intestinal hurry can be due to several things. Inflammation of the gut wall is the commonest invasive disruption. This may also arise from chemical irritation from incomplete digestion products or residues in food such as herbicides, pesticides, etc. It may also be some aspect of the food itself such as alkaloids in some plants, natural plant poisons and toxic breakdown products of meat and fish. Fibre plays a crucial role in combating the irritation of gut contents and binds very potentially dangerous materials, preventing contact with the gut wall.
Intact villal structure of intestinal wall
Any process that destroys or minimises the villus structure of the gastro-intestinal cell wall will adversely affect absorption. This may occur as the result of chronic, persistent irritation or acute degenerative events. Again, fibre and water are protective. Such diseases as Crohn’s Disease and diverticular disease are common end-results.
Absorption sites within the intestinal tract
Different materials within our food have different sites for maximal absorption. There is a whole range of normally acceptable areas for them to pass through. There is also a range of transport mechanisms that the body can use. Some of them are active, requiring energy expenditure to perform, and others are passive, occurring provided there is sufficient material present in the lumen of the tract to drive the absorption. In general, the following list is standard for most people.
a Inorganic minerals salts are absorbed in the first 6 inches or so of the jejunum/ileum
b Fats are absorbed over the mid ileal section, mainly (see below – lacteals)
c Carbohydrates are mainly absorbed through the first 1/3rd. of the ileum, although much sugar balancing occurs in the colon
d Proteins, amino acids and peptides are absorbed through most of the length of the ileum, but especially the last 2/3rds
e Vitamin B12, many antibiotics and other drugs and other vitamins are absorbed through the very low end of the ileum and the ascending part of the colon
f Nutrients produced by friendly bacteria in the gut are mostly absorbed from the ascending colon, as this is where the bacteria live.
In the ascending and transverse colon much of the water, electrolyte and sugar balancing occurs between the inside and outside world, except for, perhaps the kidneys.
It is also in this area that the symbiotic (living mutually together) bacteria live. It is reasonable, therefore, that their products should be absorbed from this area. These include: Vitamin K – Vitamin B12 – Biotin – Vitamin D – Folic acid and many of the B vitamins in small quantities.