Metabolism of 14C- and 3H-labeled l-ascorbic acid in human scurvy

Baker, Eugene M.; Hodges, Robert E.; Hood, James; Sauberlich, Howerde E.; March, Steven C.; Canham, John E.

doi:10.1093/ajcn/24.4.444

Cited by 135 publications

(43 citation statements)

References 15 publications

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“…118 The clinical features of vitamin C deficiency include follicular hyperkeratosis, inflamed and bleeding gums, perifollicular haemorrhages and impaired wound healing. 118,238,239 Deficiency in infants may result in bone abnormalities, such as impaired bone growth and disturbed ossification, haemorrhagic symptoms and resultant anaemia. 240 While scurvy is rare in modern societies (as previously discussed), subclinical vitamin C deficiency is relatively common even in affluent societies.…”

Section: Deficiencies: Relevance and Prevalencementioning

confidence: 99%

Essential Role of Vitamin C and Zinc in Child Immunity and Health

Maggini

Wenzlaff

Hornig³

2010

J Int Med Res

100

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With the progressive elimination of dietary protein-energy deficits, deficiencies of micronutrients are emerging as the limiting factors in ensuring children's optimal health. Data from several countries in Asia and Latin America indicate that deficiencies of vitamin C and zinc continue to be at alarming levels. This article reviews the roles of vitamin C and zinc in supporting children's growth and development, with a particular focus on the complementary roles they play in supporting immune functions and combating infections. The contemporary relevance of vitamin C and zinc deficiency in the Asian and Latin American regions, both undergoing a rapid nutritional transition, are also discussed. Overall, there is increasing evidence that deficiency of vitamin C and zinc adversely affects the physical and mental growth of children and can impair their immune defences. Nutrition should be the main vehicle for providing these essential nutrients; however, supplementation can represent a valid support method, especially in developing regions.

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Section: Deficiencies: Relevance and Prevalencementioning

confidence: 99%

Essential Role of Vitamin C and Zinc in Child Immunity and Health

Maggini

Wenzlaff

Hornig³

2010

J Int Med Res

100

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“…Threshold urinary excretion of vitamin C was reported at the 60-mg daily dose (3,4,7,8 tTo whom reprint requests should be addressed.…”

Section: Introductionmentioning

confidence: 99%

“…The recommended dietary allowance (RDA) for vitamin C is 60 mg daily, based on threshold urinary excretion of the vitamin and on preventing the vitamin C deficiency disease scurvy with a margin of safety (1,2).. Ingestion of 60 mg daily was proposed to prevent scurvy for [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] days if vitamin C intake ceased (1)(2)(3)(4)(5)(6)(7). Threshold urinary excretion of vitamin C was reported at the 60-mg daily dose (3,4,7,8).…”

Section: Introductionmentioning

confidence: 99%

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Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance.

Levine

Conry‐Cantilena

Wang

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

1,120

1,011

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Determinants of the recommended dietary allowance (RDA) for vitamin C include the relationship between vitamin C dose and steady-state plasma concentration, bioavailability, urinary excretion, cell concentration, and potential adverse effects. Because current data are inadequate, an in-hospital depletion-repletion study was conducted. Seven healthy volunteers were hospitalized for 4-6 months and consumed a diet containing <5 mg of vitamin C daily. Steady-state plasma and tissue concentrations were determined at seven daily doses of vitamin C from 30 to 2500 mg. Vitamin C steady-state plasma concentrations as a function of dose displayed sigmoid kinetics. The steep portion of the curve occurred between the 30-and 100-mg daily dose, the current RDA of 60 mg daily was on the lower third of the curve, the first dose beyond the sigmoid portion of the curve was 200 mg daily, and complete plasma saturation occurred at 1000 mg daily. Neutrophils, monocytes, and lymphocytes saturated at 100 mg daily and contained concentrations at least 14-fold higher than plasma. Bioavailability was complete for 200 mg of vitamin C as a single dose. No vitamin C was excreted in urine of six of seven volunteers until the 100-mg dose. At single doses of 500 mg and higher, bioavailability declined and the absorbed amount was excreted. Oxalate and urate excretion were elevated at 1000 mg of vitamin C daily compared to lower doses. Based on these data and Institute of Medicine criteria, the current RDA of 60 mg daily should be increased to 200 mg daily, which can be obtained from fruits and vegetables. Safe doses of vitamin C are less than 1000 mg daily, and vitamin C daily doses above 400 mg have no evident value.The recommended dietary allowance (RDA) for vitamin C is 60 mg daily, based on threshold urinary excretion of the vitamin and on preventing the vitamin C deficiency disease scurvy with a margin of safety (1, 2).. Ingestion of 60 mg daily was proposed to prevent scurvy for 30-45 days if vitamin C intake ceased (1-7). Threshold urinary excretion of vitamin C was reported at the 60-mg daily dose (3,4,7,8 tTo whom reprint requests should be addressed.

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“…In a rat model of chronic ethanol ingestion, this altered GSH homeostasis in the ELF (14) resulted in increased susceptibility to sepsis-induced acute lung injury as well as impaired alveolar type II cell function and viability (1,5,12). An important role for GSH availability as a predisposing factor to the development of acute lung injury was demonstrated by the ability of GSH precursors to attenuate injury in the rat model (4,5,14).…”

mentioning

confidence: 99%

Glutathione availability modulates alveolar macrophage function in the chronic ethanol-fed rat

Brown

Ping²,

Harris³

et al. 2007

American Journal of Physiology-Lung Cellular and Molecular Phys

113

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Brown LAS, Ping X-D, Harris FL, Gauthier TW. Glutathione availability modulates alveolar macrophage function in the chronic ethanol-fed rat. Am J Physiol Lung Cell Mol Physiol 292: L824-L832, 2007. First published November 22, 2006; doi:10.1152/ajplung.00346.2006.-We have previously demonstrated that chronic alcohol exposure decreases glutathione in the alveolar space. Although alcohol use is associated with decreased alveolar macrophage function, the mechanism by which alcohol impairs macrophage phagocytosis is unknown. In the current study, we examined the possibility that ethanol-induced alveolar macrophage dysfunction was secondary to decreased glutathione and subsequent chronic oxidative stress in the alveolar space. After 6 wk of ethanol ingestion, oxidant stress in the alveolar macrophages was evidenced by a 30-mV oxidation of the GSH/GSSG redox potential (P Յ 0.05). For control macrophages, ϳ80% internalized fluorescent Staphylococcus aureus were added in vitro. In contrast, only 20% of the macrophages from the ethanol-fed rats were able to bind and internalize fluorescent S. aureus. This ethanol-induced decreased capacity for phagocytosis was paralleled by increased apoptosis. When added to the ethanol diet, the glutathione precursors procysteine or N-acetyl cysteine normalized glutathione and oxidant stress in the epithelial lining fluid as well as the alveolar macrophages to control values. This attenuation of oxidant stress was associated with normalization of macrophage phagocytosis and viability. These results suggested that decreased glutathione availability in the alcoholic lung contribute to alveolar macrophage dysfunction via oxidative stress, resulting in not only decreased function but decreased viability. oxidative stress; apoptosis; lung; antioxidants A HISTORY OF CHRONIC ALCOHOL abuse increases the risk for infection, particularly in the lung (2). Although many mechanisms are undoubtedly involved, the increased risk of respiratory infections by alcoholics is partially due to an impaired immune response of the resident alveolar inflammatory cell, the alveolar macrophage. This impaired response is due in part to decreased ability of alveolar macrophages to phagocytose and clear infectious particles from the airways (3, 11). Equally important is impaired release of proinflammatory cytokines, chemokines, and oxidant radicals required for microbial killing (28).In the epithelial lining fluid (ELF) of the alveoli, the antioxidant glutathione (GSH) is essential for the detoxification of endogenous and exogenous oxidant radicals and protection of cells residing in the airway and alveolus. Under stressed conditions such as hyperoxia, the alveolar macrophage rely on the ELF pool of GSH to provide amino acids for de novo GSH synthesis (9), to protect themselves from oxidant injury (20) and maintain membrane integrity during their respiratory burst (30). Thus availability of extracellular GSH or its precursor amino acids is essential to maintain intracellular macrophage GSH homeostasis necessary for o...

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Metabolism of 14C- and 3H-labeled l-ascorbic acid in human scurvy

Cited by 135 publications

References 15 publications

Essential Role of Vitamin C and Zinc in Child Immunity and Health

Essential Role of Vitamin C and Zinc in Child Immunity and Health

Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance.

Glutathione availability modulates alveolar macrophage function in the chronic ethanol-fed rat

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