The importance of bioavailability
|This chart represents one of the more optimistic views of vitamin C bioavailability. A National Institutes of Health study suggests that only 200 mg of a single dose, regardless of size, actually gets into the bloodstream. Bioavailability, is only half of the picture, however. The nutrient must also be able to pass into individual cells.|
When all of a nutrient is absorbed into the bloodstream, as in a direct intravenous injection, the bioavailability is 100%. If only a quarter of an ingested nutrient is absorbed, the bioavailability is 25%. Of course, bioavailability also depends on and is limited by other factors such as declining health status, advancing age, and the presence of other substances that compete for absorption.
The process of uptake from the digestive system varies greatly from nutrient to nutrient. Vitamin C is absorbed almost exclusively in the small intestine and requires the presence of transport proteins. For vitamin C, these transport proteins are called sodium-dependent vitamin C co-transporters (SVCTs). A lack of these proteins produces a corresponding lack of vitamin C uptake. Published research confirms that SVCTs (transport proteins) tightly regulate vitamin C bioavailability.
In one study with non-liposome-encapsulated vitamin C, 19 mg of a 20 mg oral dose entered the bloodstream — a bioavailability of 98%. As the dose size increased beyond 30 mg, the bioavailability decreased drastically. They reported that a dose of 12,000 mg produced a maximum bioavailability of 16%!
A study by the National Institutes of Health reveals an even more restrictive control of non-liposome-encapsulated vitamin C uptake. It found that a maximum of 200 mg of non-liposome-encapsulated vitamin C is bioavailable at any given time. What happens to all non-absorbed vitamin C? It moves into the colon where it is excreted. For some individuals, an excess of vitamin C in the colon causes several unpleasant symptoms including cramps and diarrhea.
|Cellular uptake is required to obtain maximum benefit from nutrients. Recent fluorescent microscopy from laboratory tests with LivOn's "Smart" lyposomal Nano-spheres®®, confirms passage of these liposomes across cellular membranes and into cultured liver cells. The bright magenta spots show that uptake of fluorescent-dye-tagged liposomes.|
Once vitamin C enters the bloodstream, an active transport process is needed for the nutrient to move across any cellular membrane. This process can be just as restrictive as the one that initially limited the nutrient's entrance into the bloodstream. Much of the vitamin C that is not actively transported into the cells will be filtered out by the kidneys and passed in the urine.
Liposome encapsulation overcomes all these bioavailability and cellular uptake restrictions because liposomes do not rely on SVCTs or any other carrier transport system. Instead, due to their size and composition, they are able to passively absorb through the intestinal wall and through cellular membranes. As a result, liposome-encapsulated nutrients (like Lypo-Spheric™ Vitamin C) provide a greatly enhanced bioavailability (delivery into the bloodstream) and greatly improved delivery into individual cells.