When we take oral supplements, they are digested within the stomach via intrinsic factors. Within the stomach, the enzymes, gastric acids, and the intrinsic factors may not be adequate or overly acidic. This then means that the vitamins/minerals will not be absorbed.
There are several reasons why the stomach can fail to absorb vitamins/minerals. These include those with autoimmune diseases affecting the gut such as chromes and celiac disease. Others who have had extreme surgery nearby or on the stomach such as gastric bands may also find they are unable to absorb vitamins/minerals. Integrity and function of the intestinal lining can be influenced by:
However, for those that can, only roughly 20% nutrition is absorbed. It starts with digestion within the small intestine where fats, proteins and carbs are absorbed, and where essential enzymes must be present – unless that person has a problem or a reason why.
Next, the nutrients is absorbed within the large intestine where mostly water and minerals is absorbed. Then, transport of the nutrients goes to the liver for detoxification and processing. It is then delivered from the liver to the blood vessels going towards the rest of the body where it is the absorbed from the blood vessels and travelling to tissues. From the tissues it is absorbed into the cells. The cells lining the intestinal tract, which carry out the function of transporting vitamins and nutrients, must be healthy and intact for proper absorption of vitamins to occur.