Rate of excretion of vitamin C in human urine

King, G. S.; Beins, Michael; Larkin, Jennifer; Summers, B. M.; Ordman, Alfred B.

doi:10.1007/bf02435011

Cited by 12 publications

(14 citation statements)

References 17 publications

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“…But analyzing the 12-hour clearance af ter intakes of 500 mg and 1 and 2 g vitamin C, the investigators demonstated a clear depen dence on plasma concentrations. Due to satu ration, the proportion of the dose recovered in the urine decreased from 73.2 ± 25.7% at an intake of 500 mg to 35.8 ± 12.4% at an intake of 2 g vitamin C. A recent study confirmed that at daily intakes of 250 mg for 8 days no significant amounts of ascorbic acid were re covered in the urine; but at a dose of 500 mg it was detectable in the urine at least for the first 12 h. In order to obtain continuously detect able levels, it was necessary to give a dose of at least 500 mg vitamin C every 12 h [12]. Thus, it can be concluded that comparatively small increases in urinary ascorbic acid occur, even when vitamin C intakes are greatly increased.…”

Section: Kinetics and Metabolism Of Vitamin C In Humansmentioning

confidence: 99%

No Contribution of Ascorbic Acid to Renal Calcium Oxalate Stones

Gerster¹

1997

Ann Nutr Metab

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Even though a certain part of oxalate in the urine derives from metabolized ascorbic acid (AA), the intake of high doses of vitamin C does not increase the risk of calcium oxalate kidney stones due to physiological regulatory factor: gastrointestinal absorption as well as renal tubular reabsorption of AA are saturable processes, and the metabolic transformation of AA to oxalate is limited as well. Older assays for urinary oxalate favored in vitro conversion of AA to oxalate during storage and processing of the samples. Recurrent stone formers and patients with renal failure who have a defect in AA or oxalate metabolism should restrict daily vitamin C intakes to -100 mg. But in the large-scale Harvard Prospective Health Professional Follow-Up Study, those groups in the highest quintile of vitamin C intake (> 1,500 mg/day) had a lower risk of kidney stones than the groups in the lowest quintiles.

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Section: Kinetics and Metabolism Of Vitamin C In Humansmentioning

confidence: 99%

No Contribution of Ascorbic Acid to Renal Calcium Oxalate Stones

Gerster¹

1997

Ann Nutr Metab

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“…Our previous work [15] demonstrated that when AA is taken orally, the concentration in urine rises over 4 hr, remains elevated for the next 12 hr, and then falls rapidly, unless another dose of AA has been consumed. A single daily dose of 2 g will elevate the bladder concentration for at most 12 hr.…”

Section: Discussionmentioning

confidence: 99%

“…When Lamm was publishing his megavitamin protocol, he was unaware of Ordman's discovery [15] that AA must be taken twice a day (BID) to maintain elevated levels in the serum, a result we showed next for calcium [16] and eventually assumed for all water-soluble nutrients. In 1994, we published in AGE [15] that when people consume AA orally, AA intake above 500 mg is excreted in the urine over 12 hr, and that 500 mg must be consumed twice a day to guarantee continuous excretion of excess in the urine (Figure 2).…”

Section: Introductionmentioning

confidence: 99%

“…In 1994, we published in AGE [15] that when people consume AA orally, AA intake above 500 mg is excreted in the urine over 12 hr, and that 500 mg must be consumed twice a day to guarantee continuous excretion of excess in the urine (Figure 2). Levine [9] showed the relationship between oral AA dosage and serum levels, confirming Ordman's conclusion that 500 mg AA BID produces the highest statistically significant serum concentration of Vitamin C [AA] in people.…”

Section: Introductionmentioning

confidence: 99%

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Two Grams BID Is an Oral Dosage of Vitamin C to Reduce the Risk of Recurrence of Superficial Bladder Carcinoma

Folk¹,

Downs²,

Ordman

2015

JCT

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“…Together with glutathione, ascorbic acid is an important reserve of reducing capacity and is accumulated to a certain extent in the body. However, excessive amounts are immediately eliminated so it is important to have a continuous intake of vitamin C with the diet (King et al 1994;Padayatty et al 2003). Vitamin E is instead the principal vitamin with a lipophilic structure and for this reason it is indispensable for protection of the cellular membranes and other subcellular lipid structures.…”

Section: Antioxidantsmentioning

confidence: 99%

Quality and Potential Healthy Traits in Vegetables and Berries

Sambo

Nicoletto

2013

Food Quality, Safety and Technology

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In recent years, the sensitivity of consumers and producers towards the environment and health topics has increased significantly, and these issues are involving more and more the agricultural world. Much has been done in terms of cropping systems and technology, but the issues relating to the quality and nutritional value of products turn out to be more complex and sensitive. In this regard, the consumer is more aware of these issues thanks to the many suggestions offered daily both in the health and in a healthy diet.In this sense, this chapter aims to provide a current status of the concept of quality in the context of vegetable products and highlight its importance especially in order to promote vegetables by improving the final consumer diet. In this regard, the indicative pattern of the chapter could include three main sections. The first concerns about the identification and exploration of the quality concept and its evolution over time with respect to all aspects that contribute to its perception by the consumer. Moreover the technical-agronomic factors and environmental factors that determine the product quality associated with pre-harvest until the ripening stage will be considered. Finally, in the last section of this chapter, we will refer to the quality maintenance in post-harvest considering the evolution of multiple physiological aspects (antioxidants, phenols, vitamins, macro-and micronutrients, etc.) to the hypothetical purchase of the product by the consumer. During all the steps described so far, in which quality is involved, we will consider the potential health traits and benefits relevant to the health of the consumer trying to provide a clear and complete view in this research field.

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Rate of excretion of vitamin C in human urine

Cited by 12 publications

References 17 publications

No Contribution of Ascorbic Acid to Renal Calcium Oxalate Stones

No Contribution of Ascorbic Acid to Renal Calcium Oxalate Stones

Two Grams BID Is an Oral Dosage of Vitamin C to Reduce the Risk of Recurrence of Superficial Bladder Carcinoma

Quality and Potential Healthy Traits in Vegetables and Berries

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