there are literally shitloads (read: shitloads
) of studies on vit C as you all can imagine, great thread so far.. I don't supp with it to any extreme degree other than what's in the multi and my normal bb diet, etc... no 5g daily or anything like that... however, these are just a few studies if anyone wants to peruse them... can post more later after these are discussed or whatever... just seems to be a LOT of info on this, some of it conflicting.
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Mega-dose vitamin C in treatment of the common cold: a randomised controlled trial.
Audera C, Patulny RV, Sander BH, Douglas RM.
National Centre for Epidemiology and Population Health, Australian National University, Canberra, ACT.
OBJECTIVE: To determine the effect of large doses of vitamin C in the treatment of the common cold. STUDY DESIGN: Double-blind, randomised clinical trial with four intervention arms: vitamin C at daily doses of 0.03g ("placebo"), 1 g, 3g, or 3g with additives ("Bio-C") taken at onset of a cold and for the following two days. PARTICIPANTS AND SETTING: 400 healthy volunteers were recruited from staff and students of the Australian National University, Canberra, ACT, between May 1998 and November 1999. The trial continued for 18 months. INTERVENTIONS: Participants were instructed to commence medication when they had experienced early symptoms of a cold for four hours, and to record daily their symptoms, severity, doctor visits and use of other medications. MAIN OUTCOME MEASURES: Duration of symptoms and cold episodes; cumulative symptom severity scores after 7, 14 and 28 days; doctor visits; and whether participants guessed which medication they were taking. RESULTS: 149 participants returned records for 184 cold episodes. No significant differences were observed in any measure of cold duration or severity between the four medication groups. Although differences were not significant, the placebo group had the shortest duration of nasal, systemic and overall symptoms, and the lowest mean severity score at 14 days, and the second lowest at 7 and 28 days. CONCLUSIONS: Doses of vitamin C in excess of 1 g daily taken shortly after onset of a cold did not reduce the duration or severity of cold symptoms in healthy adult volunteers when compared with a vitamin C dose less than the minimum recommended daily intake.
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Vitamin C prevents cigarette smoke-induced oxidative damage in vivo.
Panda K, Chattopadhyay R, Chattopadhyay DJ, Chatterjee IB.
Dr. B. C. Guha Centre for Genetic Engineering and Biotechnology, and the Department of Biochemistry, Calcutta University College of Science, Calcutta, India.
Our recent in vitro results [4] indicate that cigarette smoke induces oxidation of human plasma proteins and extensive oxidative degradation of the guinea pig lung, heart, and liver microsomal proteins, which is almost completely prevented by ascorbic acid. In this paper, we substantiate the in vitro results with in vivo observations. We demonstrate that exposure of subclinical or marginal vitamin C-deficient guinea pigs to cigarette smoke causes oxidation of plasma proteins as well as extensive oxidative degradation of the lung microsomal proteins. Cigarette smoke exposure also results in some discernible damage of the heart microsomal proteins. The oxidative damage has been manifested by SDS-PAGE, accumulation of carbonyl and bityrosine, as well as loss of tryptophan and protein thiols. Cigarette smoke exposure also induces peroxidation of microsomal lipids as evidenced by the formation of conjugated dienes, malondialdehyde, and fluorescent pigment. Cigarette smoke-induced oxidative damage of proteins and peroxidation of lipids are accompanied by marked drop in the tissue ascorbate levels. Protein damage and lipid peroxidation are also observed in cigarette smoke-exposed pair-fed guinea pigs receiving 5 mg vitamin C/animal/day. However, complete protection against protein damage and lipid peroxidation occurs when the guinea pigs are fed 15 mg vitamin C/animal/day. Also, the cigarette smoke-induced oxidative damage of proteins and lipid is reversed after discontinuation of cigarette smoke exposure accompanied by ascorbate therapy. The results, if extrapolated to humans, indicate that comparatively large doses of vitamin C may protect the smokers from cigarette smoke-induced oxidative damage and associated degenerative diseases.
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Vitamin C for preventing and treating the common cold.
Douglas RM, Chalker EB, Treacy B.
National Centre for Epidemiology and Population Health, The Australian National University, Canberra, ACT, Australia, 0200.
[email protected]
BACKGROUND: The role of oral ascorbic acid (vitamin C) in the prevention and treatment of colds remains controversial despite many controlled trials. There have also been a number of efforts to synthesize and/or overview the results of these trials, and controversy over what these overviews tell us. OBJECTIVES: The objective of this review was to answer the following two questions: (1) Does regular high dosage supplementation with vitamin C reduce the incidence of colds? (2) Does taking vitamin C in high doses at the onset of a cold have a therapeutic effect? SEARCH STRATEGY: This review currently deals only with published trials from two previously published reviews by Kleijnen 1989 and Hemila 1992. SELECTION CRITERIA: Randomised and non-randomised trials of vitamin C taken to prevent or treat the common cold. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and assessed trial quality. MAIN RESULTS: Thirty trials were included. The quality of the included trials was variable. Vitamin C in doses as high as one gram daily for several winter months, had no consistent beneficial effect on incidence of the common cold. For both preventive and therapeutic trials, there was a consistently beneficial but generally modest therapeutic effect on duration of cold symptoms. This effect was variable, ranging from -0.07% to a 39% reduction in symptom days. The weighted difference across all of the studies revealed a reduction of a little less than half a symptom day per cold episode, representing an 8% to 9% reduction in symptom days. There was no clear indication of the relative benefits of different regimes or vitamin C doses. However in trials that tested vitamin C after cold symptoms occurred, there was some evidence that a large dose produced greater benefits than lower doses. REVIEWER'S CONCLUSIONS: Long term daily supplementation with vitamin C in large doses daily does not appear to prevent colds. There appears to be a modest benefit in reducing duration of cold symptoms from ingestion of relatively high doses of vitamin C. The relation of dose to therapeutic benefit needs further exploration.
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Relative hyperoxaluria, crystalluria and haematuria after megadose ingestion of vitamin C.
Auer BL, Auer D, Rodgers AL.
Department of Chemistry, University of Cape Town, South Africa.
BACKGROUND: Long-term or high-dosage consumption of vitamin C may play a role in calcium oxalate kidney stone formation. The present study was undertaken to determine the biochemical and physicochemical risk factors in a male subject who developed haematuria and calcium oxalate crystalluria after ingestion of large doses of ascorbic acid for 8 consecutive days. METHODS: Twenty-four-hour urine samples were collected before and during the ascorbic acid ingestion period as well as after the detection of haematuria. A special procedure was implemented for urine collections to allow for oxalate, ascorbate and other urinalysis. Oxalate was determined in the presence of EDTA to prevent in vitro conversion to ascorbic acid, whereas ascorbate itself was determined by manual titration in a redox method using the dye dichlorophenolindophenol. Urinalysis data were used to compute calcium oxalate relative supersaturations and Tiselius risk indices, whereas scanning electron microscopy was used to examine urinary deposits. RESULTS: Oxalate excretion increased by about 350% during ascorbate ingestion before haematuria. Ascorbate concentrations also increased dramatically but appeared to reach a plateau maximum. Increasing calcium excretion was accompanied by decreasing potassium and phosphate values. The calcium oxalate relative supersaturation and Tiselius risk index increased during vitamin C ingestion and large aggregates of calcium oxalate dihydrate crystals were observed by scanning electron microscopy immediately after the detection of haematuria. CONCLUSION: High percentage metabolic conversion of ascorbate to oxalate in this subject caused relative hyperoxaluria and crystalluria, the latter manifesting itself as haematuria. Clinicians need to be alerted to the potential dangers of large dose ingestion of vitamin C in some individuals.
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The effect of ascorbic acid ingestion on the biochemical and physicochemical risk factors associated with calcium oxalate kidney stone formation.
Auer BL, Auer D, Rodgers AL.
Chemistry Department, University of Cape Town, South Africa.
The present study was undertaken to determine the effect of ingestion of large doses of vitamin C on urinary oxalate excretion and on a number of other biochemical and physicochemical risk factors associated with calcium oxalate urolithiasis. A further objective was to determine urinary ascorbate excretion and to relate it qualitatively to ingested levels of the vitamin and oxalate excretion. Ten healthy males participated in a protocol in which 4 g ascorbic acid was ingested for 5 days. Urines (24 h) were collected prior to, during and after the protocol. The urine collection procedure was designed to allow for the analysis of oxalate in the presence and absence of an EDTA preservative and for the analysis of ascorbic acid by manual titration using 2,6 dichlorophenolindophenol. Physicochemical risk factors such as the calcium oxalate relative supersaturation and Tiselius risk index were calculated from urine composition. The results showed that erroneously high analytical oxalate levels occur in the asence of preservative. In the preserved samples there was no significant increase in oxalate excretion at any stage of the protocol. Ascorbate excretion increased when vitamin C ingestion commenced but levelled out after 24 hours suggesting that saturation of the metabolic pool is reached within 24 hours after which ingested ascorbic acid is excreted unmetabolized in the urine. While transient statistically significant changes occurred in some of the biochemical risk factors, they were not regarded as being clinically significant. There were no changes in either the calcium oxalate relative supersaturation or Tiselius risk index. It is concluded that ingestion of large doses of ascorbic acid does not affect the principal risk factors associated with calcium oxalate kidney stone formation.
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Vitamin C, the placebo effect, and the common cold: a case study of how preconceptions influence the analysis of results.
Hemila H.
Department of Public Health, University of Helsinki, Finland.
A large number of placebo-controlled studies have shown that vitamin C supplementation alleviates the symptoms of the common cold, but widespread skepticism that vitamin C could have any significant effect remains. One of the most influential common cold studies, published in 1975, was carried out by Thomas Karlowski et al, at the National Institutes of Health. Their placebo consisted of lactose, which can easily be distinguished from ascorbic acid by taste. Karlowski et al, found a 17% decrease in the duration of cold episodes in the group administered vitamin C (6 g/day); however, they suggested that the decrease was entirely due to the placebo effect. In this article it will be shown that the placebo effect is not a valid explanation for the results of the Karlowski study, as it is inconsistent with their results. This is an important conclusion for two reasons. First, the placebo explanation becomes even more unreasonable as regards the reported benefits found in several other studies with valid placebo tablets. Second, as the results from the Karlowski study are not due to the placebo effect, their results can be used to assess the quantitative effects of vitamin C supplementation. The most important conclusions from Karlowski's study are that therapeutic vitamin C supplementation during a common cold episode appears to be as effective as regular supplementation, and that there appears to be linear dose dependency at least up to 6 g/day. These findings suggest that large therapeutic vitamin C doses might alleviate the symptoms of the common cold substantially.
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