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Vitamin C and Health

Vitamin C—Sources, Physiological Role, Kinetics, Deficiency, Use, Toxicity, and Determination - Feb 2021

36 pages
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Vitamin C (L-ascorbic acid) has been known as an antioxidant for most people. However, its physiological role is much larger and encompasses very different processes ranging from facilitation of iron absorption through involvement in hormones and carnitine synthesis for important roles in epigenetic processes.
Contrarily, high doses act as a pro-oxidant than an anti-oxidant.
This may also be the reason why plasma levels are meticulously regulated on the level of absorption and excretion in the kidney. Interestingly, most cells contain vitamin C in millimolar concentrations, which is much higher than its plasma concentrations, and compared to other vitamins.
The role of vitamin C is well demonstrated by miscellaneous symptoms of its absence—scurvy. The only clinically well-documented indication for vitamin C is scurvy.
The effects of vitamin C administration on

  • cancer
  • cardiovascular diseases, and
  • infections are rather minor or even debatable in the general population.

Vitamin C is relatively safe, but caution should be given to the administration of high doses, which can cause overt side effects in some susceptible patients (e.g., oxalate renal stones). Lastly, analytical methods for its determination with advantages and pitfalls are also discussed in this review.

Neuroprotective properties of vitamin C: A Scoping Review of pre-clinical and clinical studies - Feb 2021

DOI: 10.1089/neu.2020.7443 no free PDF

There is a need for novel neuroprotective therapies. We aimed to review the evidence for exogenous vitamin C as a neuroprotective agent. MEDLINE, Embase and Cochrane library databases were searched from inception to May 2020. Pre-clinical and clinical reports evaluating vitamin C for acute neurological injury were included. Twenty-two pre-clinical and 11 clinical studies were eligible for inclusion. Pre-clinical studies included models of traumatic and hypoxic brain injury, subarachnoid and intracerebral hemorrhage and ischemic stroke. The median [IQR] maximum daily dose of vitamin C in animal studies was 120 [50-500] mg/kg. Twenty-one animal studies reported improvements in biomarkers, functional outcome or both. Clinical studies included single reports in neonatal hypoxic encephalopathy, traumatic brain injury and subarachnoid hemorrhage and eight studies in ischemic stroke. The median maximum daily dose of vitamin C was 750 [500-1000] mg, or ~10 mg/kg for an average size adult male. Apart from one case series of intra-cisternal vitamin C administration in subarachnoid hemorrhage, clinical studies reported no patient centered benefit. While pre-clinical trials suggest that exogenous vitamin C improves biomarkers of neuroprotection, functional outcome and mortality, these results have not translated to humans.
However, clinical trials used ~1/10th of the vitamin C dose of animal studies.

The Role of Vitamin C in Two Distinct Physiological States: Physical Activity and Sleep - Dec 2020

Nutrients, 20 Dec 2020, 12(12) DOI: 10.3390/nu12123908 PDF
Otocka-Kmiecik A1, Król A1

This paper is a literature overview of the complex relationship between vitamin C and two opposing physiological states, physical activity and sleep. The evidence suggests a clinically important bidirectional association between these two phenomena mediated by different physiological mechanisms. With this in mind, and knowing that both states share a connection with oxidative stress, we discuss the existing body of evidence to answer the question of whether vitamin C supplementation can be beneficial in the context of sleep health and key aspects of physical activity, such as performance, metabolic changes, and antioxidant function.
We analyze the effect of ascorbic acid on the main sleep components, sleep duration and quality, focusing on the most common disorders: insomnia, obstructive sleep apnea, and restless legs syndrome. Deeper understanding of those interactions has implications for both public health and clinical practice.

Mortality in septic patients treated with vitamin C: a systematic meta-analysis Jan 2021

Critical Care (London, England), 05 Jan 2021, 25(1):17 DOI: 10.1186/s13054-020-03438-9 PDF
Scholz SS1, Borgstedt R1, Ebeling N1, Menzel LC2, Jansen G1, Rehberg S1

Supplementation of vitamin C in septic patients remains controversial despite eight large clinical trials published only in 2020. We aimed to evaluate the evidence on potential effects of vitamin C treatment on mortality in adult septic patients.

Data search included PubMed, Web of Science, and the Cochrane Library. A meta-analysis of eligible peer-reviewed studies was performed in accordance with the PRISMA statement. Only studies with valid classifications of sepsis and intravenous vitamin C treatment (alone or combined with hydrocortisone/thiamine) were included.

A total of 17 studies including 3133 patients fulfilled the predefined criteria and were analyzed. Pooled analysis indicated no mortality reduction in patients treated with vitamin C when compared to reference (risk difference - 0.05 [95% CI - 0.11 to - 0.01]; p = 0.08; p for Cochran Q = 0.002; I2 = 56%). Notably, subgroup analyses revealed an improved survival, if vitamin C treatment was applied for 3-4 days (risk difference, - 0.10 [95% CI - 0.19 to - 0.02]; p = 0.02) when compared to patients treated for 1-2 or > 5 days. Also, timing of the pooled mortality assessment indicated a reduction concerning short-term mortality (< 30 days; risk difference, - 0.08 [95% CI - 0.15 to - 0.01]; p = 0.02; p for Cochran Q = 0.02; I2 = 63%). Presence of statistical heterogeneity was noted with no sign of significant publication bias.

Although vitamin C administration did not reduce pooled mortality, patients may profit if vitamin C is administered over 3 to 4 days. Consequently, further research is needed to identify patient subgroups that might benefit from intravenous supplementation of vitamin C.

Vitamin C and Immune Function - Nov 2017

Nutrients 2017, 9(11), 1211; https://doi.org/10.3390/nu9111211 PDF

Vitamin C is an essential micronutrient for humans, with pleiotropic functions related to its ability to donate electrons. It is a potent antioxidant and a cofactor for a family of biosynthetic and gene regulatory enzymes. Vitamin C contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system. Vitamin C supports epithelial barrier function against pathogens and promotes the oxidant scavenging activity of the skin, thereby potentially protecting against environmental oxidative stress. Vitamin C accumulates in phagocytic cells, such as neutrophils, and can enhance chemotaxis, phagocytosis, generation of reactive oxygen species, and ultimately microbial killing. It is also needed for apoptosis and clearance of the spent neutrophils from sites of infection by macrophages, thereby decreasing necrosis/NETosis and potential tissue damage. The role of vitamin C in lymphocytes is less clear, but it has been shown to enhance differentiation and proliferation of B- and T-cells, likely due to its gene regulating effects. Vitamin C deficiency results in impaired immunity and higher susceptibility to infections. In turn, infections significantly impact on vitamin C levels due to enhanced inflammation and metabolic requirements. Furthermore, supplementation with vitamin C appears to be able to both prevent and treat respiratory and systemic infections. Prophylactic prevention of infection requires dietary vitamin C intakes that provide at least adequate, if not saturating plasma levels (i.e., 100–200 mg/day), which optimize cell and tissue levels. In contrast, treatment of established infections requires significantly higher (gram) doses of the vitamin to compensate for the increased inflammatory response and metabolic demand.

Special issue on Vitamin C in Nutrients - 2017 (15 studies)

URL for Special Issue FREE PDFs

  • Inadequate Vitamin C Status in Prediabetes and Type 2 Diabetes Mellitus: Associations with Glycaemic Control, Obesity, and Smoking
  • Vitamin C Intake is Inversely Associated with Cardiovascular Mortality in a Cohort of Spanish Graduates: the SUN Project
  • Vitamin C Status Correlates with Markers of Metabolic and Cognitive Health in 50-Year-Olds: Findings of the CHALICE Cohort Study
  • Vitamin C Depletion and All-Cause Mortality in Renal Transplant Recipients
  • Emerging Evidence on Neutrophil Motility Supporting Its Usefulness to Define Vitamin C Intake Requirements
  • Poor Vitamin C Status Late in Pregnancy Is Associated with Increased Risk of Complications in Type 1 Diabetic Women: A Cross-Sectional Study
  • Vitamin C and Immune Function
  • Vitamin C Status and Cognitive Function: A Systematic Review
  • The Roles of Vitamin C in Skin Health
  • Protective Role for Antioxidants in Acute Kidney Disease
  • Vitamin C, Aging and Alzheimer’s Disease
  • Does Vitamin C Influence Neurodegenerative Diseases and Psychiatric Disorders?
  • Vitamin C and Infections

Vitamin C consumption has decreased

Trends in Vitamin C Consumption in the United States:1999–2018 PDF

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Vitamin C In VitaminDWiki

Vitamin C books (have not looked at them)

Created by admin. Last Modification: Sunday February 14, 2021 19:20:54 GMT-0000 by admin. (Version 22)

Attached files

ID Name Comment Uploaded Size Downloads
15038 Vitamin C and Immune Function.pdf admin 13 Feb, 2021 22:38 986.18 Kb 59
15037 Mortality in septic patients.pdf PDF 2021 admin 13 Feb, 2021 22:27 1.72 Mb 54
15036 The Role of Vitamin C in Two Distinct Physiological States - Physical Activity and Sleep.pdf admin 13 Feb, 2021 22:20 418.76 Kb 62
15035 Trends Vit C.jpg admin 13 Feb, 2021 22:09 100.01 Kb 132
15034 Trends in Vitamin C Consumption in the United States 1999-2018.pdf admin 13 Feb, 2021 22:08 2.53 Mb 63
15033 Vitamin C—Sources, Physiological Role, Kinetics, Deficiency, Use, Toxicity, and Determination.pdf PDF 2021 admin 13 Feb, 2021 21:32 910.09 Kb 99
15032 Overview of the possible role of vitamin C in management of COVID-19.pdf PDF 2020 admin 13 Feb, 2021 21:30 765.41 Kb 72
15031 Vit C and COVID-19.pdf PDF 2020 admin 13 Feb, 2021 21:30 372.70 Kb 59
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