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Bioavailability (Vitamin C)

Bioavailability of [non-liposome-encapsulated] vitamin C Gerster H, et al, (1987)

Vitamin C (non-liposomal) bioavailability decreases with dose size Gropper S, et al, (2009)

Bioavailability of (non-liposomal) vitamin C decreases rapidly with dose size Levine M, et al,(1996)

Liposome-encapsulated vitamin C dramatically increases blood levels Hickey S, et al, (2008)

Ascorbate: The Science of Vitamin C Hickey S, et al, (2004)


Bioavailability (GSH, a peptide)

Liposome encapsulation improves peptide bioavailability Parmentier J, et al (2011)


Liposomes

Non-liposome-encapsulated vitamin C bioavailability decreases with dose size Groff, et al, (1995)

Liposome-encapsulated vitamin C dramatically increases blood levels Hickey S, et al, (2008)

Liposomes used to deliver drugs to specifically targeted cells Kelly C, et al, (2011)

Liposomal encapsulation improves delivery of therapeutic agent Mitsopoulos P, et al, (2011)

Liposome encapsulation improves peptide bioavailability Parmentier J, et al, (2011)

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Studies and Resources

References/Citations/Summaries

Gropper SS, Smith JL, Groff JL, (2009), Advanced Nutrition and Human Metabolism, West Publishing Co. p 313.

Vitamin C [non-liposomal] bioavailability decreases with dose size
As dose size increases, bioavailabiity decreases dramatically. The authors express this finding by stating that 98% of a 20 mg oral dose of [non-liposome-encapsulated] vitamin C is bioavailable (enters the bloodstream) whereas only 16% of a 12,000 mg dose does so.

Gerster H, (1987), Human vitamin C requirements, Z Ernahrungswiss. Jun;26(2):125-37.

Bioavailability of [non-liposome-encapsulated] vitamin C
Based on previous recommended daily allowance (RDA) studies by the National Institutes of Health, author suggests that a 200 mg daily intake of vitamin C is sufficient to provide tissue saturation. By implication, any additional vitamin C would not be used or bioavailable. He does also suggest that smokers and those in disease states may have a higher requirement for vitamin C. [NOTE: Hickey & Roberts (2004) debunk the flawed nature of these NIH studies]

Hickey S., Roberts H, Miller N, (2008), "Pharmacokinetics of oral vitamin C" Journal of Nutritional & Environmental Medicine July 31.

Liposome-encapsulated vitamin C dramatically increases blood levels
Authors found that a liposome-encapsulated vitamin C nearly doubled bioavailability over that thought possible from studies published by the National Institutes of Health.

Hickey S, Roberts H, (2004), Ascorbate: The Science of Vitamin C, 2004.

Ascorbate: The Science of Vitamin C
This book presents a new model, describing the action of vitamin C in health. It demonstrates conclusively that the establishment has misinterpreted the evidence. The dynamic flow model explains the current results and points the way for future experiments. This book is a must for people who want to understand the scientific evidence and support for high-dose vitamin C.

Kelly C, Jefferies C, Cryan SA, (2011), "Targeted liposomal drug delivery to monocytes and macrophages," J Drug Deliv.

Liposomes used to deliver drugs to specifically targeted cells
Liposomes can be used to effectively deliver therapeutic agents particular cell types (mononuclear phagocytic system, particularly macrophages). These cells are of particular importance in the immune system.

Levine M, Conry-Cantilena C, Wang Y, Welch RW, Washko PW, Dhariwal KR, Park JB, Lazarev A, Graumlich JF, King J, Cantilena LR. (1996), "Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance," Proc Natl Acad Sci U S A. 1996 Apr 16;93(8):3704-9..

Bioavailability of (non-liposomal) vitamin C decreases rapidly with dose size
Authors report very rapid decline in bioavailability [of non-liposome-encapsulated vitamin C] with dose size. The "steep portion of the curve" starts between 30 mg and 100 mg of daily dose. Based on their findings, they suggest that "vitamin C daily doses above 400 mg have no evident value." This conclusion is based on the faulty presupposition that the appearance of vitamin C in the urine indicates all bodily tissues are saturated and the body requires no additional vitamin C. This assumption is clearly refuted by Hickey, et al. in his book Ascorbate: The Science of Vitamin C referenced above.

Mitsopoulos P, Suntres ZE, (2011), "Protective Effects of Liposomal N-Acetylcysteine against Paraquat-Induced Cytotoxicity and Gene Expression," J Toxicol.

Liposomal encapsulation improves delivery of therapeutic agent
N-acetylcysteine (NAC) was encapsulated in liposomes and administered as a trea™ent for paraquat poisoning. Pretrea™ent with this liposomal NAC was found to be more effective than conventional drugs in reducing the effects of paraquat poisoning.

Parmentier J, Thewes B, Gropp F, Fricker G, (2011), "Oral peptide delivery by tetraether lipid liposomes," Int J Pharm. Jun 2.

Liposome encapsulation improves peptide bioavailability
Liposomes were used to deliver peptides agents which normally break down in the stomach. Bioavailability in some tests improved by 460%.


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