The True Meaning of Bioavailability
Bioavailability indicates the amount of a substance that is absorbed by a target location within the body. This target location can be anywhere in the body… blood, cells, tissue, etc. For many drugs and nutrients, the target location is the blood. IV delivery does offer 100% bioavailability when blood is the target. However, for vitamin C, the target location is typically inside the cell - where free radicals, toxins, and pathogens do the most harm.
While IV delivery puts 100% of the vitamin C directly into the blood, it does not guarantee 100% absorption into the cells. IV vitamin C relies on the body’s active transport system to carry the vitamin C into the cells. This system uses transport proteins, called sodium-dependent vitamin C co-transporters (SVCTs), to carry vitamin C through special portals that lead to the inside of cells. The challenge with SVCTs is that they can only carry one molecule of vitamin C through one portal at a time, and the number of SVCTs and portals is limited. This means absorption of vitamin C into the cells (or, its bioavailability), may be severely restricted if there are not enough SVCTs or open portals available.
IV Vitamin C: The Ultimate Consumer
It’s also important to understand that for vitamin C to benefit the health of the cell, it must be in its active (reduced) form. If the vitamin C has been rendered inactive (oxidized) during transport, it has lost the electrons it needs to function properly. The good news is that inactive vitamin C can become active again; the bad news is that it must take electrons from other antioxidants within the cell (i.e. glutathione) to do this.
This isn’t such a bad thing if you have tons of antioxidants just hanging out inside your cells, but this is not usually the case for anyone over the age of 25, or anyone with ill health. Let’s assume that a majority of the IV vitamin C makes it into the cells, and there are plenty of antioxidants on-hand to ensure the vitamin C stays active within the cells. Mission accomplished, right? Well, sort of. The entire process of transporting vitamin C into the cells and reactivating inactive vitamin C consumes A LOT of valuable energy within the cell. Since an ample supply of cellular energy is necessary to stay alive, the energy used in this process needs to be replaced as quickly as possible. So what do vitamin C experts recommend when you need high-doses of vitamin C delivered into the blood and the cells? Two things: IV vitamin C (if available) and liposome encapsulated vitamin C.
Liposome Encapsulated Vitamin C
Liposomes are tiny spheres made from Essential Phospholipids. They form a double-layer membrane around active vitamin C, and protect it from destruction in the digestive system. Because the liposome membrane is made of phospholipids – the same material that makes up the cellular membrane - the liposome is able to bypass the body’s active transport system (those SVCTs and portals we mentioned earlier) and incorporate itself directly into the cell membrane. When this happens, the vitamin C that’s inside of the liposome is delivered to the cell in its active state (it has all of its electrons), and without using a lot of cellular energy.
