Vitamin C (ascorbic acid) is a water-soluble micronutrient. Unlike some other vitamins, human beings cannot manufacture their own vitamin C and must rely on outside sources (food and supplements) to obtain it. Considering this nutrient’s extremely important role in relation to human health, we would all do well to make sure we obtain adequate amounts. This role includes its necessity for the formation of collagen protein found in skin, connective tissue, cartilage and bone; it is also an antioxidant nutrient. It is essential for wound healing, affects immune responses, helps maintain strength in blood vessels, helps protect the body against infections, bacterial toxins and viruses, influences formation of hemoglobin, absorption of iron from intestinal tract, and deposition of iron in liver tissue, and assists in the secretion of hormones from adrenals. A deficiency of vitamin C may result in symptoms such as pink or hemorrhagic skin follicles, hemorrhages in the eye, inflamed gums, joint pains, excessive hair loss, easy bruising and bleeding gums.1
Vitamin C Bioavailability
Depletion-repletion experiments demonstrated that the concentration of plasma vitamin C is tightly controlled by intestinal absorption, tissue transport and renal kidney reabsorption.2 So how well is vitamin C absorbed in supplemental form? The answer is it depends upon the dosage you take. Plasma vitamin C concentration rises steeply at intakes between 30 and 100 mg/day. Plasma concentrations of ascorbate reach steady state at concentrations between 60 and 80 micromoles/L (μmol/L). Typically, this is observed at doses between 200 to 400 mg/day in healthy young adults, with some individual variation.3,4
One hundred percent absorption efficiency is observed when ingesting vitamin C at doses up to 200 mg at a time. Higher doses (>500 mg) result in less vitamin C being absorbed as the dose increases. Once plasma vitamin C concentrations reach saturation, additional vitamin C is largely excreted in the urine. Notably, intravenous administration of vitamin C bypasses absorptive control in the intestine such that very high concentrations of vitamin C can be achieved in the plasma; within a few hours, renal excretion restores vitamin C to baseline plasma concentrations.5
So, if you want to use higher doses of vitamin C for the potential benefits provided (such as fighting upper respiratory tract infections), how can you do it without literally having your vitamin C go down the drain? The answer is to choose an appropriate form of vitamin C. In this case I’m referring to vitamin C lipid metabolites (PureWay C).
About Vitamin C Lipid Metabolites
Vitamin C metabolites were developed to increase vitamin C absorption as well as prolong blood and tissue retention of this nutrient. The concept was that, since lipophilic molecules can easily be partitioned into, and interact with, cells in a non-toxic way, they were seen as potentially the most useful carrier ligands for delivering vitamin C. The PureWay-C composition is a conjugated complex with select citrus bioflavonoids and lipid metabolites. Now let’s review the published research on vitamin C lipid metabolites.
Absorption Rates and Free Radical Scavenging Activity
The first absorption study6 with vitamin C-lipid metabolites investigated the cellular absorption rates, antioxidant and free radical scavenging activity in human cell lines with ascorbic acid (AA), calcium ascorbate (CaA), calcium ascorbate-calcium threonate-dehydroascorbate (Ester-C), and vitamin C-lipid metabolites (PureWay-C). Results were that, compared to AA, CaA and calcium ascorbate-calcium threonate-dehydroascorbate, vitamin C-lipid metabolites (PureWay-C) had more rapid cellular absorption. The vitamin C-lipid metabolites also reduced pesticide-induced T-lymphocyte aggregation (a potential immune dysfunction) by 84 percent, while calcium ascorbate-calcium threonate-dehydroascorbate reduced aggregation by only 34 percent. The vitamin C-lipid metabolites demonstrated free radical scavenging activity of nearly 100 percent reduction of the DPPH radical. In conclusion, vitamin C-lipid metabolites are more rapidly taken-up and absorbed by cells than other forms of vitamin C. This increased rate of absorption correlates with an increased protection of the T-lymphocytes from pesticide toxicities. Furthermore, vitamin C-lipid metabolites are a potent antioxidant and have significant free radical scavenging capabilities.
Vitamin C Uptake and Retention & CRP and Oxidized LDL Levels
While absorption in cell lines is impressive, it’s much more meaningful to assess absorption in a human clinical trial. So, a human clinical trial7 was conducted in which vitamin C serum levels, plasma C-reactive protein (CRP) and oxidized low density lipoprotein levels (LDL) were measured in healthy volunteers after oral supplementation with different forms of vitamin C. Healthy volunteers received a single oral dose of 1,000 mg vitamin C) as either ascorbic acid (AA), calcium ascorbate (CaA), vitamin C-lipid metabolites (PureWay-C), or calcium ascorbate-calcium threonate-dehydroascorbate (Ester-C). Results were that vitamin C-lipid metabolites supplementation provided a statistically significant greater serum level than calcium ascorbate at 1, 2, 4 and 6 hours post oral supplementation whereas calcium ascorbate-calcium threonate-dehydroascorbate showed a less but slightly statistically significant increase at only 1 and 4 hours. In addition, at 24 hours vitamin C-lipid metabolites maintained the highest serum levels of vitamin C, demonstrating the best retention of any of the forms tested. Oral supplementation with vitamin C-lipid metabolites also led to a greater reduction in plasma C-reactive protein and oxidized LDL levels compared to the other vitamin C formulations. In conclusion, vitamin C-lipid metabolites were more rapidly absorbed and led to higher serum vitamin C levels and greater reduction of plasma levels of inflammatory and oxidative stress markers than other forms of vitamin C.
Effects on Neurites, Fibroblasts and Xenobiotics
Vitamin C has been shown to enhance neurite outgrowth (structures on neurons that develop into axons or dendrites for communication with other neurons), promote the adhesion of fibroblasts (the principle active cells of connective tissue) during wound healing, and reduce xenobiotic-induced leukocyte hyperactivity (xenobiotics are chemical substances which are foreign to the biological system) and inflammatory damage. In this study,8 a comparison was made between vitamin C-lipid metabolites (PureWay-C), or calcium ascorbate-calcium threonate-dehydroascorbate (Ester-C) on these various cellular activities. PC12 cells (a type of catecholamine cells that synthesise, store and release norepinephrine and dopamine9) were stimulated to form neurites, fibroblasts were seeded on fibronectin, and H9 T-cells (a type of stem cell) were stimulated to aggregate with the pesticide bifenthrin. The rate of neurite formation, fibroblast adhesion and T-cell homotypic aggregation was then measured in the absence and presence of vitamin C-lipid metabolites (PureWay-C) and calcium ascorbate-calcium threonate-dehydroascorbate. Results were that:
• PureWay-C treatment extended neurites in 12 percent of PC12 cells within one hour of treatment and 45 percent of the cells extended neurites by nine hours. Ester-C extended neurites 0 percent and 15 percent at one and nine hours, respectively.
• Fibroblast adhesion to fibronectin was enhanced by 4.7-fold with a 30-minute PureWay-C treatment, while Ester-C increased fibroblast adhesion by only 1.5-fold.
• PureWay-C reduced pesticide-mediated T-cell homotypic aggregation by 83 percent within 30 minutes of treatment while the reduction seen with Ester-C was only 33 percent.
In conclusion, vitamin C-lipid metabolites were shown to have a faster and greater beneficial effect on these various cellular activities compared to calcium ascorbate-calcium threonate-dehydroascorbate.
When higher doses (>500 mg) of vitamin C are consumed, much of it is excreted into the urine. In human clinical research, vitamin C-lipid metabolites (PureWay-C) have been shown to help avoid waste by providing significantly higher absorption and retention compared to other forms of vitamin C tested. In addition, vitamin C-lipid metabolites have been shown to scavenge free radicals, reduce LDL oxidation, reduce C-reactive protein levels, enhance neurite outgrowth, promote the adhesion of fibroblasts (the principle active cells of connective tissue) during wound healing, and reduce xenobiotic-induced leukocyte hyperactivity.
1 Whitney E, Cataldo C, Rolfes S. Understanding Normal and Clinical Nutrition. Belmont, California: Wadsworth Publishing; 1998: 356-363.
2 Levine M, Padayatty SJ, Espey MG. Vitamin C: a concentration-function approach yields pharmacology and therapeutic discoveries. Adv Nutr. 2011;2(2):78-88.
3 Levine M, Padayatty SJ, Espey MG. Vitamin C: a concentration-function approach yields pharmacology and therapeutic discoveries. Adv Nutr. 2011;2(2):78-88.
4 Levine M, Conry-Cantilena C, Wang Y, et al. Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance. Proc Natl Acad Sci USA. 1996;93(8):3704-3709.
5 Padayatty SJ, Sun H, Wang Y, et al. Vitamin C pharmacokinetics: implications for oral and intravenous use. Ann Intern Med. 2004;140(7):533-537.
6 Weeks BS, Perez PP. Absorption rates and free radical scavenging values of vitamin C-lipid metabolites in human lymphoblastic cells. Med Sci Monit. 2007 Oct;13(10):BR205-10.
7 Pancorbo D, Vazquez C, Fletcher MA. Vitamin C-lipid metabolites: uptake and retention and effect on plasma C-reactive protein and oxidized LDL levels in healthy volunteers. Med Sci Monit. 2008 Nov;14(11):CR547-51.
8 Weeks BS, Perez PP. A novel vitamin C preparation enhances neurite formation and fibroblast adhesion and reduces xenobiotic-induced T-cell hyperactivation. Med Sci Monit. 2007 Mar;13(3):BR51-8.
9 Wiatrak B, Kubis-Kubiak A, Piwowar A, Barg E. PC12 Cell Line: Cell Types, Coating of Culture Vessels, Differentiation and Other Culture Conditions. Cells. 2020 Apr; 9(4): 958.
Gene Bruno, MS, MHS, the dean of academics for Huntington College of Health Sciences, is a nutritionist, herbalist, writer and educator. For more than 30 years he has educated and trained natural product retailers and health care professionals, has researched and formulated natural products for dozens of dietary supplement companies, and has written articles on nutrition, herbal medicine, nutraceuticals and integrative health issues for trade, consumer magazines and peer-reviewed publications. He can be reached at email@example.com.