Vitamin C & Fast-C Clinical Evidence

Fast C Bioavailability

Presented at Experimental Biology
Labiste K et al. A Clinical Evaluation Comparing the Bioavailability of Two Buffered Vitamin C Supplements in Healthy, Non-smoking Males. Apr. 2008. 

Topic: 
How does the bioavailability of Fast C compare to that of Ester C?

Background:

Ester C has become the leading premium brand of vitamin C, due to the fact that it has been marketed as being better absorbed than regular ascorbic acid. It is also buffered, making it easier on the stomach. How does Fast C, a new form of buffered Vitamin C, compare to Ester C?

Study Type:

Human clinical intervention trial

Study Design:

Subjects ate a diet low in vitamin C for at least one week and then took a dose of either Fast C or Ester C, followed by another week of the low Vitamin C diet and then a dose of the other brand of vitamin C. (The order of the brands was randomly assigned.) Blood was drawn pre-dosing and at 30, 60, 90, 120, 210, and 240 minutes after ingesting the supplement. Urine was also collected for 24 hours after taking the supplement.

Subjects:

5 healthy, non-smoking, young males

Dosage:

Single, 1-gram dose

Results:

Weight-adjusted concentrations of ascorbic acid in the subjects’ blood were significantly higher for Fast C than for Ester C at 60 minutes, although peak levels did not show significant difference. Fast C delivered 54% more vitamin C into the tissues in the first 2 hours than Ester C. Urinary levels of vitamin C were similar for the two brands.

Conclusion:
“[T]here were no differences in the overall absorption between the AA [ascorbic acid] products over the 4-hour test period, with [Fast C] displaying a faster rate of absorption than Ester C.”

Presented at the American College of Nutrition 
Labiste K et al. A Morales I, et al. A Clinical Evaluation Comparing The Bioavailability Of Three Vitamin C Supplements In Healthy Non-Smoking Males. Oct. 2009. 

Topic: 
How does the bioavailability of 2 formulations of Fast C compare to that of Ester C?

Background:

Fast C contains bioperine, a black pepper extract thought to increase absorption of Vitamin C.

Study Type:

Human clinical intervention trial

Study Design:

Subjects took 3 forms of Vitamin C — Ester C, Fast C with 4.06 mg of bioperine and Fast C with 5.36 mg of bioperine — in random order after eating a diet low in Vitamin C for a week. Blood was drawn before ingesting the supplement and at 30, 60, 90, 120, 210, 240 minutes and 24 hours. Urine was collected at 24 hours as well and tested for both Vitamin C and dihydroascorbic acid, the oxidized form of ascorbic acid.

Subjects:

10 healthy non-smoking young males

Results:

Blood vitamin C levels were slightly higher for both formulations of Fast C than for Ester-C. At 30 and 60 minutes, absorption was significantly greater for Fast C.

Conclusion:

“There were no differences in the overall absorption of the 3 Vitamin C products over the 24-hour test period although [Fast C] had a faster rate of absorption than Ester-C.” 

Vitamin C & Detoxification

American Journal of Clinical Nutrition 
Johnston CS, Meyer CG, and Srilakshmi JC. Vitamin C elevates red blood cell glutathione in healthy adults. 1993 Jul;58(1):103-5. 

Topic: 
What is the effect of vitamin C on blood levels of glutathione?

Background:

Glutathione is an antioxidant manufactured by the body that helps repair damage to cells caused by free radicals. Can vitamin C enhance its healing power?

Study Type:

Human clinical intervention trial

Study Design:

Double-blind. Subjects consumed diets low in vitamin C and took a placebo daily for 1 week, followed by a 500-mg dose of vitamin C for 2 weeks, followed by a 2,000-mg dose for another 2 weeks, and finishing with a final week of placebo.

Dosage:

500 mg/day for 2 weeks, followed by 2,000 mg/day for 2 weeks

Results:

After ingesting the lower dose of C, glutathione levels rose by nearly 50% from baseline (with individual subjects’ levels rising anywhere from 8 to 84%). However, the higher dose did not result in significantly higher glutathione levels than the lower dose. After the washout period, glutathione levels returned to baseline.

Conclusion:

“These data indicate that vitamin C supplementation (500 mg/d) maintains reduced glutathione concentrations in blood and improves the overall antioxidant protection capacity of blood.” [Note: reduced glutathione refers to glutathione in its active antioxidant form.] 

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Vitamin C & Antioxidant Status

American Journal of Clinical Nutrition 
Lenton KJ, et al. Vitamin C augments lymphocyte glutathione in subjects with ascorbate deficiency. 2003 Jan; 77(1):189-95. 

Topic: 
Can vitamin C supplementation improve glutathione levels in the lymphocytes of subjects with vitamin C deficiency?

Background:

Both vitamin C and glutathione play an important part in defending the body against free radicals. Can supplementation with vitamin C enhance levels of glutathione in lymphocytes (a type of white blood cell)?

Study Type:

Human clinical intervention trial

Study Design:

Subjects took a vitamin C supplement for 13 weeks, after which their lymphocyte levels of both vitamin C and glutathione were measured. They then took a placebo for 13 weeks.

Subjects:

48 healthy men and women, aged 25-64, smokers and non-smokers, with low plasma levels of vitamin C (ascorbate)

Dosage:

500 or 1,000 mg, for 13 weeks, followed by placebo for 13 weeks

Results:

After supplementation with vitamin C, ascorbate levels in lymphocytes increased by 51% while glutathione levels rose by 18%. After placebo, ascorbate and glutathione levels fell nearly back to baseline levels. Changes in ascorbate levels after supplementation were strongly associated with changes in glutathione levels.

Conclusion:

“Vitamin C supplements increase glutathione in human lymphocytes.” 

British Journal of Nutrition 
Hemilä H. Vitamin C intake and susceptibility to the common cold. 1997 Jan;77(1):59-72. 

Topic: 
Under what circumstances does vitamin C affect susceptibility to the common cold?

Background:

The role of vitamin C in preventing the common cold has been widely studied but vitamin C has not been definitively shown to reduce the incidence of colds. Are there special circumstances when vitamin C helps prevent colds?

Study Type:

Review paper

Dosage:

Varied by study

Results:

The researchers pooled results from the 6 largest studies of vitamin C supplementation. Overall, cold incidence was not reduced in the groups taking vitamin C as compared to the placebo groups. However, theorizing that vitamin C supplementation might make more difference in populations with lower-than-average levels of the nutrient, the researchers focused on 4 studies with British male school children and students. They found that those taking vitamin C did enjoy a highly significant reduction in the number of infections.

Conclusion:

“Thus these studies with British males indicate that vitamin C intake has physiological effects on susceptibility to common cold infections, although the effect seems quantitatively meaningful only in limited groups of people.” 

Vitamin C & Immune Function

Cochrane Database of Systematic Reviews 
Douglas RM, et al. Vitamin C for preventing and treating the common cold. 2004 Oct 18;(4):CD000980. Updated 2007 Jul 18;(3):CD000980. 

Topic: 
Does vitamin C reduce the incidence, duration or severity of the common cold?

Background:

Vitamin C is widely used by the public to prevent and treat the common cold, even though its efficacy for this purpose has been debated since the 1940s or earlier.

Study Type:

Review paper

Dosage:

200 mg/day or higher

Results:

The researchers performed a meta analysis (a study that compiles and analyzes the results of previous studies) of 30 placebo-controlled studies with a total of 11,350 participants. They found:

  • While taking vitamin C did not prevent colds in the general population, it did reduce the incidence of colds in people involved engaged in vigorous exercise (such as skiing or running a marathon) or in those exposed to extremely cold environments.
  • There was an 8% reduction in the duration of colds for adults and a 13.6% reduction for children.
  • Participants taking vitamin C took fewer days off school and work.
  • Participants who caught their colds naturally showed more benefit in reduced severity of cold symptoms from taking vitamin C than those who were infected in the laboratory.

Conclusion:

“[T]he consistent and statistically significant small benefits of duration and severity for those using regular vitamin C prophylaxis indicates that vitamin C plays some role in respiratory defence mechanisms…[R]outine mega-dose prophylaxis is not rationally justified for community use. But evidence suggests that it could be justified in people exposed to brief periods of severe exercise or cold environments.” 

International Journal of Sports Medicine 
Hemilä H. Vitamin C and common cold incidence: a review of studies with subjects under heavy physical stress. 1996 Jul;17(5):379-83. 

Topic: 
Can vitamin C reduce the incidence of the common cold in subjects engaged in strenuous physical exercise?

Background:

Research has found that subjects performing heavy physical exercise are at increased risk of contracting upper respiratory infections. Can vitamin C reduce this risk?

Study Type:

Review paper of 3 placebo-controlled studies

Dosage:

600-1,000 mg/day

Results:

Researchers analyzed 3 studies: one of children at a skiing camp in the Alps, one of soldiers training in Northern Canada and one of runners in a 90 km race. All 3 studies showed that those subjects who supplemented with vitamin C suffered fewer colds than those who took placebo.

Conclusion:

“Accordingly, the results of the three studies suggest that vitamin C supplementation may be beneficial for some of the subjects doing heavy exercise who have problems with frequent upper respiratory infections.” 

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Annals of Nutrition and Metabolism 
Wintergerst ES, Maggini S and Hornig DH. Immune-enhancing role of vitamin C and zinc and effect on clinical conditions. 2006;50(2):85-94. 

Topic: 
Can vitamin C and zinc improve immune function?

Background:

Levels of vitamin C in plasma and leukocytes (white blood cells) fall rapidly when the body is fighting infection or under stress. Can vitamin C and zinc help the immune system respond more effectively to infections?

Study Type:

Review paper

Dosage:

Up to 1 gram/day

Results:

Supplementation with vitamin C was found to enhance the function of various components of the immune system, such as antimicrobial cells, natural killer cells, the proliferation of lymphocytes (a kind of white blood cell), chemotaxis (the movement of cells toward or away from a chemical stimulant), and delayed-type hypersensitivity (over-reactions of the immune system such as allergies or autoimmune diseases). Vitamin C also protects cells from free radicals and inflammation.

Conclusion:

“These trials document that adequate intakes of vitamin C and zinc ameliorate symptoms and shorten the duration of respiratory tract infections including the common cold. Furthermore, vitamin C and zinc reduce the incidence and improve the outcome of pneumonia, malaria, and diarrhea infections, especially in children in developing countries.” 

Vitamin C Mechanism of Action:

Vitamin C boosts the body’s defenses by increasing its antioxidant, immune-stimulating and detoxification powers.

  • Antioxidant: Vitamin C helps raise blood levels of the antioxidant glutathione by protecting it from oxidation.
  • Immune-stimulation: Vitamin C improves the function of components of the immune system, such as antimicrobial and natural killer cell activation, lymphocyte proliferation, chemotaxis and delayed-type hypersensitivity.
  • Detoxification: Vitamin C helps detoxify the body by decreasing absorption of heavy metals, such as lead.

Due to its combination of absorption-enhancing agents, such as bioperine (a black pepper extract), and special buffered vitamin C mineral salts, Fast C has a faster rate of absorption than other brands of vitamin C. This may be because piperine increases the permeability of the villi (hair-like projections that cover the lining of the small intestine) and enhances the osmotic balance, the process that keeps minerals in bodily fluids at healthy concentrations — not too diluted and not too concentrated. Piperine partitions easily, thus making it easier to cross membranes and barriers, so it helps substances in its presence to be absorbed more efficiently. 
 

Vitamin C & Collagen Peptide

Actas Fermo-sifiliográficas. 
Valdés F. Vitamin C. 2006 Nov;97(9):557-68. 

Topic: 
What are the health benefits of vitamin C?

Background:

Vitamin C, also called ascorbic acid, is a water-soluble vitamin crucial for human health. What are its functions in the body?.

Study Type:

Review paper

Summary:

Vitamin C: 
Is necessary for the synthesis of collagen fibers. It acts as a reducing agent (a compound that donates an electron) and introduces a hydroxl group (consisting of an oxygen and hydrogen molecule) to the amino acids proline and lysine, a process that increases the stability of collagen. A vitamin C deficiency disrupts the hydroxylation process — leading to less stable collagen — and results in symptoms of scurvy, such as weakness, joint pain, lesions, and slow healing. 

Protects the body against free radical damage. 
Cannot be synthesized by the body and must be included in the diet. 
Has an RDA of 90 mg/day for men and 75 mg/day for women. 

Vitamin C Mechanism of Action:

Vitamin C is needed for the synthesis of collagen from lysine and proline amino acids through various enzymes, including proline hydroxylase and lysyl hydroxylase. Vitamin C stimulates the synthesis and expression of collagen types I and III. Vitamin C also increases the wavy pattern of the stratum corneum as well as increasing lipids in between cells, thus improving skin hydration.