Introduction: Vitamin C
Vitamin C, also known as the antiscorbutic factor, is a water-soluble vitamin; it is particularly perishable when exposed to intense heat and oxidation (exposure to oxygen).
Vitamin C is an essential compound for all living beings, however the human body having lost the ability to produce vitamin C from glucose, due to a genetic mutation that occurred during its evolutionary process, as opposed to almost totality of animal species, must necessarily take it through food.
The essential roles of vitamin C include:
- Synthesis of collagen (supporting protein, it is the most abundant protein in the body and determines the formation of the skin, tendons, cartilages, intervertebral discs, cornea, vitreous body, blood vessels, placenta ...)
- Antioxidant function;
- Support function of the immune system, with anti-inflammatory and immunological effects;
- Metabolism of iron and folic acid;
- Conversion of cholesterol into bile acids;
- Conversion of the amino acid tryptophan into serotonin.
Where is it?
Foods of plant origin are globally considered a good source of vitamin C, although the specific quantity depends on the product in question, the nature of the soil and the growing climate, the state of ripeness at the time of harvest, the time and conditions. conservation, and any preparatory work for consumption. while foods of animal nature generally do not contain it in significant quantities.
The most common and widespread products in the Italian diet that contain high concentrations of vitamin C are:
- Chili Peppers
- Black cabbage
- Turnip greens
- Rocket salad
- Brussels sprouts
- Swiss chard
- Mandarin oranges
- Green radicchio
What does vitamin C deficiency entail?
The human body can only store small amounts of vitamin C within the liver; in the event of a prolonged shortage, these stocks run out quickly.
Vitamin C deficiency leads to impaired collagen synthesis, which is too unstable (this causes scurvy symptoms). Furthermore, the lack of vitamin C causes the malfunction of many other enzymes that depend on it, especially enzymes involved in energy metabolism.
Scurvy is the most serious disease that occurs as a result of chronic dietary vitamin C deficiency with spots and subcutaneous bleeding (especially on the thighs and legs), spongy gums, impaired hair growth and poor wound healing. People with scurvy appear pale, depressed, and move with difficulty. In advanced scurvy, more extensive wounds open, suppuration, tooth loss, bone abnormalities appear, and eventually death.
The lack of direct feedback between the body's need and the dietary intake of ascorbic acid causes much of the human population to be in a state of varying levels of permanent or transient deficiencies. Since vitamin C is directly involved in many life processes, as seen above, even a moderate deficiency can have serious health consequences. This can easily be prevented with a diet adjustment and / or additional supplementation.
Liposomal Vitamin C
Liposomal vitamin C is an advanced pharmaceutical form of vitamin C, which is complexed with lipid structures derived from soy, better known as liposomes.
Liposomes are molecules consisting of a hydrophilic portion and a lipophilic portion that are organized in spherical formations that contain vitamin C within them; in fact, liposomes are organized showing the lipophilic component on the outside, that is, akin to cell membranes, while the hydrophilic component remains inside in close contact and affinity with vitamin C.
Vitamin C present in the bloodstream is effectively excreted by the kidneys through urine, but this complex has been shown to certainly improve the bioavailability of vitamin C, increasing the body's ability to absorb and / or retain it.
How liposomes work and their benefits
At the intestinal level, the liposomal complexes are conveyed, like the lipids, into the lymphatic circulation (rather than into the bloodstream), thus skipping the first pass metabolism in the liver, which can determine its significant inactivation.
The bioavailability of the liposomal formulation has been demonstrated in medical experiments on healthy volunteers. In addition, another important aspect of the liposome formulation is the ability to administer large doses of vitamin C over an extended period of time, as the lipid capsule mitigates the irritation of the gastrointestinal tract that typically accompanies large oral doses of vitamin C.
Finally, another important feature of liposomal vitamin C is that the liposome formation process does not require the use of toxic organic solvents.
Efficacy of liposomal vitamin C versus standard vitamin C
Vitamin C is usually administered orally in crystalline form or as an aqueous solution, which makes it susceptible to degradation in the gastrointestinal tract.
Liposomes, as mentioned, reduce the degradation of vitamin C, slow down its release, improve its absorption and slow down its renal expulsion.
In the study conducted by Łukawski and colleagues in 2019, serum vitamin C concentration profiles in healthy volunteers were compared after single oral administration of liposomal vitamin C and standard vitamin C. The study was conducted on 20 volunteers (10 women and 10 men aged between 31 and 65). Each participant was equipped with a peripheral venous catheter, which allowed for multiple blood draws within the time frame of the study. Each participant was given a single dose of 10 g of vitamin C, in free form and in liposomal form, dissolved / suspended in 250 ml of water. After vitamin C administration, blood samples were taken at 30 min, 60 min, 90 min, 120 min, 180 min, 240 min, and 360 min. The result of the experiment is shown in figure 1.
Figure 1. Profili of average concentration of vitamin C in serum for two groups of people, following oral intake of 10 g of crystalline vitamin C in the form of aqueous solution (squares) and liposomal vitamin C (circles). Source: Łukawski et al (2019).
The graph below describes a significant increase in the bioavailability of vitamin C in the liposomal form compared to standard vitamin C: vitamin Cmax (maximum serum concentration of vitamin C) reaches higher values following administration of liposomal vitamin C rather than standard vitamin C, as shown by the peak concentration 180 minutes after administration. Furthermore, for the liposomal formulation, the delay time of the maximum blood vitamin C concentration (Tmax) is approximately 1 hour longer than for the free form (Tmax = 180 min vs. 96 min). The increased half-life (t1 / 2> 6 h vs. t1 / 2 = 4 h) and the elevated AUC (area under the concentration / time curve) (81 570 µµ * min vs 45 330 µµ * min) indicate that the presence of liposomes increases the bioavailability of vitamin C.
In summary, a higher concentration of vitamin C in the blood over a longer period of time makes liposomal vitamin C more effectively available to the body's cells than the standard, crystalline form of vitamin C.
Source of the study: Maciej Łukawski, Paulina Dałek, Tomasz Borowik, Aleksander Foryś, Marek Langner, Wojciech Witkiewicz & Magdalena Przybyło (2019): New oral liposomal vitamin C formulation: properties and bioavailability, Journal of Liposome Research, DOI: 10.1080 / 0898210. 1630642