Active Transport of l-Ascorbic Acid in the Human Ileum

Stevenson, Nancy R.

doi:10.1016/s0016-5085(19)32749-0

Cited by 66 publications

(26 citation statements)

References 9 publications

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“…The existence of specific vitC transporters were proposed long before the actual transporters could be identified [42,74,75,76,77,78,79,80,81,82]. The transport was found to be concentration-, energy-, temperature- and sodium-dependent, satiable and mediated by two different components [42,74,75,76,77,78,79,80,81,82].…”

Section: Vitamin C Transportmentioning

confidence: 99%

“…The transport was found to be concentration-, energy-, temperature- and sodium-dependent, satiable and mediated by two different components [42,74,75,76,77,78,79,80,81,82]. Two specific transporters were defined by Tsukaguchi and co-workers as sodium-dependent vitamin C transporter (SVCT) 1 and SVCT2 [83].…”

Section: Vitamin C Transportmentioning

confidence: 99%

“…The absorption of both ASC and DHA takes place in all segments of the small intestine (duodenum, jejunum and ileum) [35,82,104]. The release of vitC from intestinal and renal epithelial cells after luminal absorption has not yet been conclusively determined, although both passive diffusion and facilitated diffusion through volume-sensitive anion-channels has been suggested [44].…”

Section: Vitamin C Transportmentioning

confidence: 99%

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Regulation of Vitamin C Homeostasis during Deficiency

2013

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Large cross-sectional population studies confirm that vitamin C deficiency is common in humans, affecting 5%–10% of adults in the industrialized world. Moreover, significant associations between poor vitamin C status and increased morbidity and mortality have consistently been observed. However, the absorption, distribution and elimination kinetics of vitamin C in vivo are highly complex, due to dose-dependent non-linearity, and the specific regulatory mechanisms are not fully understood. Particularly, little is known about how adaptive mechanisms during states of deficiency affect the overall regulation of vitamin C transport in the body. This review discusses mechanisms of vitamin C transport and potential means of regulation with special emphasis on capacity and functional properties, such as differences in the Km of vitamin C transporters in different target tissues, in some instances demonstrating a tissue-specific distribution.

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Section: Vitamin C Transportmentioning

confidence: 99%

Section: Vitamin C Transportmentioning

confidence: 99%

Section: Vitamin C Transportmentioning

confidence: 99%

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Regulation of Vitamin C Homeostasis during Deficiency

2013

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“…Early studies on the small intestine in rats revealed that ascorbate uptake is a passive process, resulting mainly in intestinal mucosa accumulation but not transport to the circulation [56]. Several studies have demonstrated a profound difference in absorption between the rat and guinea pig small intestine [57,58,59], the latter displaying a robust transepithelial transport system that is sodium-dependent [59,60,61], similar to the human ileum [61,62]. A recent study in rats monitored the absorption of a single oral dose of ascorbic acid or dehydroascorbic acid given by gavage.…”

Section: Review Of Studies Using Ascorbic Acidmentioning

confidence: 99%

Myths, Artifacts, and Fatal Flaws: Identifying Limitations and Opportunities in Vitamin C Research

Michels

Frei²

2013

Nutrients

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Research progress to understand the role of vitamin C (ascorbic acid) in human health has been slow in coming. This is predominantly the result of several flawed approaches to study design, often lacking a full appreciation of the redox chemistry and biology of ascorbic acid. In this review, we summarize our knowledge surrounding the limitations of common approaches used in vitamin C research. In human cell culture, the primary issues are the high oxygen environment, presence of redox-active transition metal ions in culture media, and the use of immortalized cell lines grown in the absence of supplemental ascorbic acid. Studies in animal models are also limited due to the presence of endogenous ascorbic acid synthesis. Despite the use of genetically altered rodent strains lacking synthesis capacity, there are additional concerns that these models do not adequately recapitulate the effects of vitamin C deprivation and supplementation observed in humans. Lastly, several flaws in study design endemic to randomized controlled trials and other human studies greatly limit their conclusions and impact. There also is anecdotal evidence of positive and negative health effects of vitamin C that are widely accepted but have not been substantiated. Only with careful attention to study design and experimental detail can we further our understanding of the possible roles of vitamin C in promoting human health and preventing or treating disease.

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“…It is water soluble and an acid. It has been thought to be absorbed throughout the small intestine by passive diffusion (Nicholson and Charnock, 1942), but recent work by Stevenson (1974) and confirmed by Mellors, Nahrwold and Rose (1977) shows an active transport mechanism of absorption by the ileum. Even after major resections of the small intestine resulting in a state resembling starvation, absorption of vitamin C is still maintained and deficiency is not usually a problem (Stewart and Booth, 1964;Preston and Ascunction, 1968).…”

Section: Discussionmentioning

confidence: 99%

Scurvy and vitamin C deficiency in Crohn's disease

Linaker

1979

Postgraduate Medical Journal

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Summary A case of scurvy presenting in a patient with Crohn's disease is reported. A normal response to replacement therapy is seen. Vitamin C (ascorbic acid) deficiency was found in 7 out of 10 patients with clinically quiescent Crohn's disease, 4 of whom had an adequate oral intake of vitamin C. There was no significant difference in oral intake between patients with Crohn's disease and matched controls but there was a significant difference (P<0·001) in leucocyte ascorbic acid levels. It is recommended that patients with Crohn's disease be screened for vitamin C deficiency and receive prophylactic vitamin C supplements daily.

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Active Transport of l-Ascorbic Acid in the Human Ileum

Cited by 66 publications

References 9 publications

Regulation of Vitamin C Homeostasis during Deficiency

Regulation of Vitamin C Homeostasis during Deficiency

Myths, Artifacts, and Fatal Flaws: Identifying Limitations and Opportunities in Vitamin C Research

Scurvy and vitamin C deficiency in Crohn's disease

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