Regulation of Vitamin C Transport

Wilson, John X.

doi:10.1146/annurev.nutr.25.050304.092647

Cited by 314 publications

(306 citation statements)

References 102 publications

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“…At low concentrations, most vitamin C is absorbed in the small intestine and reabsorbed from the renal tubule [9]. However, at high concentrations, SVCT1 is down regulated [10] which limits the amount of AA absorbed from the intestine and kidney [11]. This imposes a physiological restriction on the maximal effective serum vitamin C concentration (or its bioavailability) that is attainable by oral consumption [12].…”

Section: Vitamin C Bioavailabilitymentioning

confidence: 99%

Vitamin C in Disease Prevention and Cure: An Overview

et al. 2013

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The recognition of vitamin C is associated with a history of an unrelenting search for the cause of the ancient haemorrhagic disease scurvy. Isolated in 1928, vitamin C is essential for the development and maintenance of connective tissues. It plays an important role in bone formation, wound healing and the maintenance of healthy gums. Vitamin C plays an important role in a number of metabolic functions including the activation of the B vitamin, folic acid, the conversion of cholesterol to bile acids and the conversion of the amino acid, tryptophan, to the neurotransmitter, serotonin. It is an antioxidant that protects body from free radical damage. It is used as therapeutic agent in many diseases and disorders. Vitamin C protects the immune system, reduces the severity of allergic reactions and helps to fight off infections. However the significance and beneficial effect of vitamin C in respect to human disease such as cancer, atherosclerosis, diabetes, neurodegenerative disease and metal toxicity however remains equivocal. Thus further continuous uninterrupted efforts may open new vistas to understand its significance in disease management.

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Section: Vitamin C Bioavailabilitymentioning

confidence: 99%

Vitamin C in Disease Prevention and Cure: An Overview

et al. 2013

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“…The variations in in vivo C movement after C loading may have been due to differences in the transport system. Na-dependent transporters (SVCT1 and 2) are involved in AsA transport, while passive glucose transporters (GLUTs) are involved in DAsA transport (10). These 3 transporters determine the maximum C transport in the human uriniferous tubule (glomerular filtration rates are about 1.54 and 1.39 mg/min/100 mL in males and females, respectively) and the mean renal threshold (about 1.4 mg/dL) (11).…”

Section: Resultsmentioning

confidence: 99%

Vitamin C Activity of Dehydroascorbic Acid in Humans-Association between Changes in the Blood Vitamin C Concentration or Urinary Excretion after Oral Loading-

Tsujimura

Higasa

Nakayama

et al. 2008

J Nutr Sci Vitaminol

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SummaryWe performed oral loading of AsA or DAsA (1 mmol) in subjects who had consumed a diet low in vitamin C (C) (C Յ 5 mg/d) for 3 d before loading, and measured urinary and blood vitamin C. Since the crossover method was used, the same experiment was repeated after an interval of about 1 mo in each subject. The results of the experiment including a total of 17 subjects for 2005 and 2006, were as follows. (1) There were marked individual differences in urinary C excretion. (2) The C level in 24-h urine after C loading did not differ between the two orally administered C forms (AsA and DAsA). (3) C excretion between 0 and 3 h after C loading was significantly higher ( p Ͻ 0.05) for the DAsA group, while those between 3 and 6, 6 and 9, 9 and 12, and 12 and 24 h after C loading were significantly higher ( p Ͻ 0.05 or p Ͻ 0.01) for the AsA group. (4) The blood C concentration and the increase in C 1 h after C loading were significantly higher ( p Ͻ 0.05 and p Ͻ 0.01, respectively) in the DAsA than in the AsA group. (5) Evaluation of the association between C metabolism and the single nucleotide polymorphisms of glutathione S -transferase P (GSTP) 1-1 showed a lower urinary C excretion and a significantly lower C level in 24-h urine ( p Ͻ 0.05) after AsA loading, and a significantly lower urinary C excretion between 0 and 3 h after DAsA loading ( p Ͻ 0.05) for the GA heterozygotes than for the AA homozygotes. Considering the activity of C as DAsA in humans, based on urinary and blood C levels after a single loading of C, the utilization of DAsA is equivalent to that of AsA, although the metabolic turnover time is different. The involvement of polymorphisms in the xenobiotic metabolizing enzyme, GSTP1-1, in C metabolism, particularly urinary C excretion, was also clarified. This demonstrates the necessity of considering gene polymorphisms in determining individual C requirements. An abstract of this paper was reported by the Vitamin C Research Committee (Ochanomizu University) in 2007.

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“…The glucose-ascorbate antagonism (GAA) theory [24] suggests elevated glucose levels restrict vitamin C from entering cells. Dehydroascorbic acid (DHAA) transport into cells was shown to be impaired by high blood glucose level in most cell types including adipocytes, erythrocytes, neutrophils, osteoblasts and smooth muscle cell [25,26].…”

Section: Oral and IV Vitamin C And Plasma Levelsmentioning

confidence: 99%

Metadichol® Induced High Levels of Vitamin C: Case Studies

Pr¹

2017

Vitam Miner

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We recently reported that Metadichol ® brings about a three to four-fold increase in Vitamin C levels in patients without the use of Vitamin C supplementation. In this study of 6 patients who experienced a 5-12 fold increase in plasma Vitamin C levels higher than 80-100 u mol/L level which is the highest reported to date by oral supplementation at high doses of Vitamin C. Metadichol improved in these patients TSH levels, normalized High Blood pressure, fasting glucose levels, reduced eosinophil count, high triglycerides, body fat reduction and increased bone mass, normalized sodium levels, reducing high insulin levels, increased creatinine output in urine and also reducing of Red Cell Distribution width %. Metadichol thus serves as a surrogate for Vitamin C at doses of 5 mg per day as opposed to mega doses that are currently used.

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Regulation of Vitamin C Transport

Cited by 314 publications

References 102 publications

Vitamin C in Disease Prevention and Cure: An Overview

Vitamin C in Disease Prevention and Cure: An Overview

Vitamin C Activity of Dehydroascorbic Acid in Humans-Association between Changes in the Blood Vitamin C Concentration or Urinary Excretion after Oral Loading-

Metadichol® Induced High Levels of Vitamin C: Case Studies

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