C-Vitamin

[cj8000]

500mg C-Vitamin før træning sku være godt. Nogen der kan fortælle mig why?!??!

Ved der flere der bruger det pt (Norah, Mass, Pok....)

[Stubbe]

500mg C-Vitamin før træning sku være godt. Nogen der kan fortælle mig why?!??!

Ved der flere der bruger det pt (Norah, Mass, Pok....)

Fordi det lyder bedre end 400mg og knap så vildt som 600mg. For at være lidt seriøs nøjes jeg med at påstå at effekten hviler på et meget tvivlsomt fagligt grundlag (tro kan flytte bjerge ).

[cj8000]

Fordi det lyder bedre end 400mg og knap så vildt som 600mg. For at være lidt seriøs nøjes jeg med at påstå at effekten hviler på et meget tvivlsomt fagligt grundlag (tro kan flytte bjerge ).

Og hvad er det faglige grundlag??????

Sætter det proteinsyntesen op eller eller eller??!?!

[Thomas Mikaelsen]

Og hvad er det faglige grundlag??????

Sætter det proteinsyntesen op eller eller eller??!?!

Jeg tror, at grunden til man indtager C-vitamin er, at det er en antioxidant, der hjælper med at eliminere "free radicals"/affaldsstoffer og cortisol i musklerne, stoffer som kun har negativ effekt på genopbygningen af muskelfibre.

Tvivl dog stærkt på, at det sætter proteinsyntesen op. Måske indirekte vha. de andre faktorer, men tvivler.

Spiser bl.a. selv 333 mg. i forbindelse med træning, og så 666 mg. ( ) fordelt ud over resten af dagen.

[-Elvirus-]

ved indtag på de 1000mg dagligt får du også kun 16-17 gange så meget Vitamin C, som den daglige anbefalede dosis......

[Sortiarius]

Jeg tror, at grunden til man indtager C-vitamin er, at det er en antioxidant, der hjælper med at eliminere "free radicals"/affaldsstoffer og cortisol i musklerne, stoffer som kun har negativ effekt på genopbygningen af muskelfibre.

Tvivl dog stærkt på, at det sætter proteinsyntesen op. Måske indirekte vha. de andre faktorer, men tvivler.

Spiser bl.a. selv 333 mg. i forbindelse med træning, og så 666 mg. ( ) fordelt ud over resten af dagen.

Vitamin C bruges hverken til proteinsyntese eller til at fjerne "affaldsstoffer" i musklerne, desuden er cortisol ikke et affaldsstof, men et steroidhormon der sætter sig i cellekernen. Vitamin C bruges derimod i syntesen af collagen, steroidgenesen, dannelsen af katekolaminer, dannelsen af galde, optagelse af jern og som led i tyrosinmetabolismen, og nåja, så er der den antioxidative effekt, som nok er grunden til folk spiser vitaminet som bolsjer...

Edited October 25, 2006 by Sortiarius

[cj8000]

Vitamin C bruges hverken til proteinsyntese eller til at fjerne "affaldsstoffer" i musklerne, desuden er cortisol ikke et affaldsstof, men et steroidhormon der sætter sig i cellekernen. Vitamin C bruges derimod i syntesen af collagen, steroidgenesen, dannelsen af katekolaminer, dannelsen af galde, optagelse af jern og som led i tyrosinmetabolismen, og nåja, så er der den antioxidative effekt, som nok er grunden til folk spiser vitaminet som bolsjer...

Der var en der vidste lidt der :4thumbup:

Men men men, hvad gør C-vitamin i forhold til træning (antioxidative)????

[ptpoul]

Jeg har aldrig kunne finde nogle studier der viser positiv effekt på præstation og restitution via søgninger på pubmed.

Der er bare mange fitness skribenter der anbefaler det alligevel.

Jeg har aldrig mærket nogen effekt af at indtage vitamin c i forbindelse med træning, eller som depot for generelle helbreds hensyn.

[TranceT]

Vitamin C bruges hverken til proteinsyntese eller til at fjerne "affaldsstoffer" i musklerne, desuden er cortisol ikke et affaldsstof, men et steroidhormon der sætter sig i cellekernen. Vitamin C bruges derimod i syntesen af collagen, steroidgenesen, dannelsen af katekolaminer, dannelsen af galde, optagelse af jern og som led i tyrosinmetabolismen, og nåja, så er der den antioxidative effekt, som nok er grunden til folk spiser vitaminet som bolsjer...

Link til at vitamin C ikke bruges til at bekæmpe frie radikaler med?

Hvergang jeg støder på noget om antioxidanter, står der altid noget ala:

"The vitamins C and E, are thought to protect the body against the destructive effects of free radicals. Antioxidants neutralize free radicals by donating one of their own electrons, ending the electron-"stealing" reaction. The antioxidant nutrients themselves don’t become free radicals by donating an electron because they are stable in either form They act as scavengers, helping to prevent cell and tissue damage that could lead to cellular damage and disease." - lige dette er hentet fra "www.healthchecksystems.com/antioxid.htm"

[Thomas Mikaelsen]

Jeg har aldrig kunne finde nogle studier der viser positiv effekt på præstation og restitution via søgninger på pubmed.

Der er bare mange fitness skribenter der anbefaler det alligevel.

Jeg har aldrig mærket nogen effekt af at indtage vitamin c i forbindelse med træning, eller som depot for generelle helbreds hensyn.

Så er det fordi, du ikke har ledt godt nok :

Vitamin C supplementation attenuates the increases in circulating cortisol, adrenaline and anti-inflammatory polypeptides following ultramarathon running.

Peters EM, Anderson R, Nieman DC, Fickl H, Jogessar V.

Department of Physiology, Faculty of Medicine, University of Natal, Durban, South Africa. [email protected]

The effects of vitamin C supplementation on the alterations in the circulating concentrations of cortisol, adrenaline, interleukin-10 (IL-10) and interleukin-1 receptor antagonist (IL-1Ra) which accompany ultramarathon running were measured using immuno-chemiluminescence, radioimmunoassay and ELISA procedures. Forty-five participants in the 1999 Comrades 90 km marathon were divided into equal groups (n = 15) receiving 500 mg/day Vit C (VC-500), 1500 mg/day Vit C (VC-1500) or placebo (P) for 7 days before the race, on the day of the race, and for 2 days following completion. Runners recorded dietary intake before, during and after the race and provided 35 ml blood samples 15 - 18 hrs before the race, immediately post-race, 24 hrs post race and 48 hrs post-race. Twenty-nine runners (VC-1500, n = 12; VC-500, n = 10; P, n = 7) complied with all study requirements. All post-race concentrations were adjusted for plasma volume changes. Analyses of dietary intakes and blood glucose and anti-oxidant status on the day preceding the race and the day of the race did not reveal that carbohydrate intake or plasma vitamins E and A were significant confounders in the study. Mean pre-race concentrations of serum vitamin C in VC-500 and VC-1500 groups (128 +/- 31 and 153 +/- 34 micromol/l) were significantly higher than in the P group (83 +/- 39 micromol/l). Immediate post-race serum cortisol was significantly lower in the VC-1500 group (p < 0.05) than in P and VC-500 groups. When the data from VC-500 and P groups was combined (n = 17), immediate post-race plasma adrenaline, IL-10 and IL-1Ra concentrations were also significantly lower (p < 0.05) in the VC-1500 group. The study demonstrates an attenuation, albeit transient, of both the adrenal stress hormone and anti-inflammatory polypeptide response to prolonged exercise in runners who supplemented with 1500 mg vitamin C per day when compared to < or = 500 mg per day.

Publication Types:

* Clinical Trial

* Controlled Clinical Trial

Vitamin-C har altså også indflydelse på cortisoldannelsen i kroppen.

[ptpoul]

Så er det fordi, du ikke har ledt godt nok :

Vitamin C supplementation attenuates the increases in circulating cortisol, adrenaline and anti-inflammatory polypeptides following ultramarathon running.

Peters EM, Anderson R, Nieman DC, Fickl H, Jogessar V.

Department of Physiology, Faculty of Medicine, University of Natal, Durban, South Africa. [email protected]

The effects of vitamin C supplementation on the alterations in the circulating concentrations of cortisol, adrenaline, interleukin-10 (IL-10) and interleukin-1 receptor antagonist (IL-1Ra) which accompany ultramarathon running were measured using immuno-chemiluminescence, radioimmunoassay and ELISA procedures. Forty-five participants in the 1999 Comrades 90 km marathon were divided into equal groups (n = 15) receiving 500 mg/day Vit C (VC-500), 1500 mg/day Vit C (VC-1500) or placebo (P) for 7 days before the race, on the day of the race, and for 2 days following completion. Runners recorded dietary intake before, during and after the race and provided 35 ml blood samples 15 - 18 hrs before the race, immediately post-race, 24 hrs post race and 48 hrs post-race. Twenty-nine runners (VC-1500, n = 12; VC-500, n = 10; P, n = 7) complied with all study requirements. All post-race concentrations were adjusted for plasma volume changes. Analyses of dietary intakes and blood glucose and anti-oxidant status on the day preceding the race and the day of the race did not reveal that carbohydrate intake or plasma vitamins E and A were significant confounders in the study. Mean pre-race concentrations of serum vitamin C in VC-500 and VC-1500 groups (128 +/- 31 and 153 +/- 34 micromol/l) were significantly higher than in the P group (83 +/- 39 micromol/l). Immediate post-race serum cortisol was significantly lower in the VC-1500 group (p < 0.05) than in P and VC-500 groups. When the data from VC-500 and P groups was combined (n = 17), immediate post-race plasma adrenaline, IL-10 and IL-1Ra concentrations were also significantly lower (p < 0.05) in the VC-1500 group. The study demonstrates an attenuation, albeit transient, of both the adrenal stress hormone and anti-inflammatory polypeptide response to prolonged exercise in runners who supplemented with 1500 mg vitamin C per day when compared to < or = 500 mg per day.

Publication Types:

* Clinical Trial

* Controlled Clinical Trial

Vitamin-C har altså også indflydelse på cortisoldannelsen i kroppen.

Det er da meget fint.

Men det er meget vanskeligt at finde et studie der viser at det resulterter i nedsat muskelømhed eller endnu vigtigere resulterer i hurtigere/bedre restitution oven på et træningspas (det er ikke lykkedes for mig trods ihærdige forsøg).

Derudover er det i denne sammenhæng styrketræning der diskuteres, ikke effekterne af et ultramarathonløb.

Ovenstående studie ville sikkert blive brugt til at sælge vitaminer til folk der styrketræner. Sådan er det ofte med kosttilskudsfabrikanter.

Enten fabrikerer de selv forskning der giver det resultat de selv ønsker. Eller også bruger de komplet irrelevante referencer som din.

[Thomas Mikaelsen]

Men det er meget vanskeligt at finde et studie der viser at det resulterter i nedsat muskelømhed

1. Hvem har påstået at C-vitamin skulle være anti-inflammatorisk? Jeg har i hvert fald ikke, og det er heller ikke derfor jeg indtager det.

eller endnu vigtigere resulterer i hurtigere/bedre restitution oven på et træningspas (det er ikke lykkedes for mig trods ihærdige forsøg).

2. Umiddelbart, dette er blot min egen konklusion, vil jeg påstå, at lavere cortisolniveau i kroppen efter træning resulterer i bedre restitution. Correct me if I'm wrong.

Derudover er det i denne sammenhæng styrketræning der diskuteres, ikke effekterne af et ultramarathonløb.

3. Korrekt, men hvis der dannes cortisol i forbindelse med træningen - jeg går ud fra, at vi er enige om, at der dannes cortisol både ved ultramarathon og styrketræning - så er det vel irrelevant, om hormonet bliver dannet ved løb eller løft.

Ovenstående studie ville sikkert blive brugt til at sælge vitaminer til folk der styrketræner. Sådan er det ofte med kosttilskudsfabrikanter.

4. Ja, det tror jeg du har helt ret i, men det er en dårlig ting? De burde måske bare helt afstå fra den dokumentation de kan finde for, at deres produkt er virksomt?

Enten fabrikerer de selv forskning der giver det resultat de selv ønsker.

5. Det er lidt af en demonisering, du der fremlægger. Der står ikke noget om, hvem der har sponseret forskningen, men med den tilgang til artiklerne på Pubmed, vil jeg påstå, at det bliver svært at finde dokumentation for noget som helst.

Eller også bruger de komplet irrelevante referencer som din.

Jeg synes jeg har kommenteret på artiklens relevans (jvf. 3)

[Sortiarius]

Link til at vitamin C ikke bruges til at bekæmpe frie radikaler med?

Hvergang jeg støder på noget om antioxidanter, står der altid noget ala:

"The vitamins C and E, are thought to protect the body against the destructive effects of free radicals. Antioxidants neutralize free radicals by donating one of their own electrons, ending the electron-"stealing" reaction. The antioxidant nutrients themselves don’t become free radicals by donating an electron because they are stable in either form They act as scavengers, helping to prevent cell and tissue damage that could lead to cellular damage and disease." - lige dette er hentet fra "www.healthchecksystems.com/antioxid.htm"

Sorry havde ikke set der stadig var liv i den her diskussion.

kan ikke se at jeg nogen steder har betvivlet at vitamin C i fysiologiske doser kan have en antioxidativ virkning på ROS, skriver faktisk netop dette som det sidste i min post..., at folk så tolker det somom, ok hvis vi spiser en masse vitamin C må det have en endnu større antioxidativ effekt, er deres eget problem - det har vi haft en diskussion om herinde tidligere - mig bekendt endte den i at de fleste meta-analyser ikke fandt nogen signifikant ændring af inflammatoriske faktorer ved indtag af vit. c som supplement - medmindre personerne da netop havde gennemført et ultramaraton og kort forinden havde fået en vit. c bolus i gram-størrelsesorden.

Anyways fandt lige en artikel:

Influence of vitamin C supplementation on oxidative and immune changes after an ultramarathon.

The purpose of this randomized study was to measure the influence of vitamin C (n = 15 runners) compared with placebo (n = 13 runners) supplementation on oxidative and immune changes in runners competing in an ultramarathon race. During the 7-day period before the race and on race day, subjects ingested in randomized, double-blind fashion 1,500 mg/day vitamin C or placebo. On race day, blood samples were collected 1 h before race, after 32 km of running, and then again immediately after race. Subjects in both groups maintained an intensity of approximately 75% maximal heart rate throughout the ultramarathon race and ran a mean of 69 km (range: 48-80 km) in 9.8 h (range: 5-12 h). Plasma ascorbic acid was markedly higher in the vitamin C compared with placebo group prerace and rose more strongly in the vitamin C group during the race (postrace: 3.21 +/- 0.29 and 1.28 +/- 0.12 microg/100 microl, respectively, P < 0.001). No significant group or interaction effects were measured for lipid hydroperoxide, F2-isoprostane, immune cell counts, plasma interleukin (IL)-6, IL-10, IL-1-receptor antagonist, or IL-8 concentrations, or mitogen-stimulated lymphocyte proliferation and IL-2 and IFN-gamma production. These data indicate that vitamin C supplementation in carbohydrate-fed runners does not serve as a countermeasure to oxidative and immune changes during or after a competitive ultramarathon race.

Effects of ascorbic acid and carbohydrate ingestion on exercise induced oxidative stress.

BACKGROUND: We studied the effects of supplementation of vitamin C and carbohydrate on acute exercise-induced lipid peroxidation. METHODS: Experimental design: two randomized controlled trials. PARTICIPANTS: 17 endurance athletes. Interventions: in study I, nine athletes repeated twice a 10.5-km maximal run and ingested in a randomized single-blind order either 2.0 g vitamin C or placebo. In study II, eight athletes repeated twice a 27-km maximal run and ingested in randomly either 105 g carbohydrate or placebo. Venous blood samples were taken before the exercise, immediately after the exercise, and after a recovery period of 90 min (study I) or 120 min (study II). Measure: serum diene conjugation, lipid peroxidation. RESULTS: In study I, there was no difference in serum diene conjugation between the trials during exercise (pre- vs post-exercise). However, during the recovery period (post-exercise vs recovery sample) serum diene conjugation concentration decreased by 11% in the vitamin C trial but not in placebo (p = 0.028). In study II, there was no difference between the carbohydrate and placebo trials. CONCLUSIONS: Vitamin C and carbohydrate do not prevent exercise-induced increase in oxidative stress, but vitamin C, being a potent aqueous antioxidant, seems to decrease the levels of diene conjugation during recovery after exercise. The clinical significance of this phenomenon needs further evaluation.

Så er det fordi, du ikke har ledt godt nok :

Vitamin-C har altså også indflydelse på cortisoldannelsen i kroppen.

Okay, lad os lige få een ting på det rene, du skrev i din oprindelige post at:

grunden til man indtager C-vitamin er, at det er en antioxidant, der hjælper med at eliminere "free radicals"/affaldsstoffer og cortisol i musklerne, stoffer som kun har negativ effekt på genopbygningen af muskelfibre.

Det giver ikke megen mening - fordi du ikke definerer affaldsstoffer, og fordi vitamin c ikke "fjerner cortisol fra musklerne".

Cortisol er et livsnødvendigt stress hormon, der måske set med pumper-øjne er noget ubrugeligt bras, men uden det ville mennesket hverken være i stand til at kapere emotionelt eller fysisk stress - den cirkulerende cortisolkoncentration varierer cirkudiant på lige fod med andre stoffer som hGH som en del af den menneskelige homeostase, det er ikke et affaldsstof.

Når cortisol cirkulerer rundt i blodbanen optages stoffet passivt i forskellige celler, da cortisol som steroid hormon har den unikke evne til at passere cellemembranen passivt (modsat fx glukose), inde i cellens cytosol bindes den til et transportermolekyle der tillader den passage ind i cellens kerne, hvorefter cellens transkription af forskellige proteiner reguleres på DNA niveau - vitamin C påvirker på ingen måde cortisols rolle som transkriptionsfaktor, eller nedbryder denne.

Noget andet er kraftig træning, ved længerevarende træning dannes store mængder af katekolaminer fra binyremarven, til denne syntese skal der, som jeg skrev i min første post, bruges vit. c, koncentrationen af denne falder derfor umiddelbart efter længere tids varende hård træning - som jeg har forstået hypotesen er dette grunden til at nogle mener at en øget koncentration af vit. c i blodet kan formindske stigningen i cortisol. Dit abstract synes at vise at dette også er tilfældet - men du bør måske lige nævne at diskussionen om hvorvidt ascorbinsyre som supplement kan sænke post-exercise koncentrationen af cortisol er noget der stadig er på hypotese planet, for at understreege dette fandt jeg en anden undersøgelse:

Vitamin C supplementation does not alter the immune response to 2.5 hours of running.

This randomized, double-blind, placebo-controlled study was designed to determine the influence of vitamin C supplementation on the immune response to 2.5 hr of high-intensity running. Twelve experienced marathon runners (VO2 max 51.6 +/- 1.5 ml.kg-1.min-1, age 40.5 +/- 2.0 years) were randomized into vitamin C (1,000 mg/day for 8 days) or placebo groups. On the test day, subjects ran at 75-80% VO2 max for 2.5 hr, with five blood samples taken before and for 6 hr after. Blood samples were analyzed for cortisol and catecholamines; leukocyte subsets; interleukin-6; natural killer cell activity; lymphocyte proliferation as induced by concanavalin A, phytohemagglutinin, and pokeweed mitogen; and granulocyte phagocytosis and activated oxidative burst. Compared with placebo, vitamin C supplementation had no significant effect on the pattern of change in any of these hormonal or immune measures following 2.5 hr of intensive running.

Jeg fandt desuden en interessant artikel

Vitamin C infusion treatment enhances cortisol production of the adrenal via the pituitary ACTH route.

The present study is an extension of our past study on the clinical use of vitamin C infusion or injection treatment in autoimmune disease and allergy which suggests that the intravenous introduction of vitamin C may enhance the activity of the endogenous cortisol in such a way as to allow clinical control of immune disorders. This time, we investigated the relation between ACTH, cortisol and vitamin C in plasma in the course of vitamin C infusion or injection treatment with and without the use of methyl-prednisolone annex, a suppressor of the homeostatic mechanism of the pituitary ACTH. A total of 4 experiments were conducted using a healthy male volunteer. Results obtained are as follows: 1) the practice of the steroid-free vitamin C infusion treatment induced a) distinct depletion of both cortisol and vitamin C from the circulation at the initial to moderate stages of the experiment, B) a small surge of plasma cortisol at the middle stage, and c) skyrocket-like rises of ACTH and cortisol of plasma at the terminal stage. 2) The use of methylprednisolone annex in the vitamin C infusion set completely suppressed the emergence of the plasma ACTH/cortisol surges of the terminal stage, but not the small surge of plasma cortisol. The synthetic steroid also suppressed the depletion of vitamin C and cortisol of the initial to moderate stages. 3) The terminal ACTH/cortisol surges of plasma were less distinct in the vitamin C infection experiment than in the vitamin C infusion experiment.

Det viser sig her, at selvom store doser af vit. c initialt sænker cortisolproduktionen, så stiger den senere, faktisk til et højere niveau end før, dette som baggrund i at faldet i cortisol initialt stimulerer ACTH på hypothalamus niveau, faktisk så meget at forskerne bag mener at vitamin c muligvis kan bruges til at dæmpe et eventuelt autoimmunt respons - det er da meget komisk, ikk?

og skulle det så vise sig, når der engang kommer en stor metaanalyse på området, at vitamin c tilskud kan reducere cortisol en smule ved ekstrem intensiv fysisk aktivitet, kan man så overveje om det i sig selv gør det fordelagtigt nok at spise vitamin c dagligt - også i lyset af hvor hurtigt post-exercise stigninger i cortisol falder igen.

Edited November 13, 2006 by Sortiarius

[Thomas Mikaelsen]

Sorry havde ikke set der stadig var liv i den her diskussion.

kan ikke se at jeg nogen steder har betvivlet at vitamin C i fysiologiske doser kan have en antioxidativ virkning på ROS, skriver faktisk netop dette som det sidste i min post..., at folk så tolker det somom, ok hvis vi spiser en masse vitamin C må det have en endnu større antioxidativ effekt, er deres eget problem - det har vi haft en diskussion om herinde tidligere - mig bekendt endte den i at de fleste meta-analyser ikke fandt nogen signifikant ændring af inflammatoriske faktorer ved indtag af vit. c som supplement - medmindre personerne da netop havde gennemført et ultramaraton og kort forinden havde fået en vit. c bolus i gram-størrelsesorden.

Anyways fandt lige en artikel:

Okay, lad os lige få een ting på det rene, du skrev i din oprindelige post at:

grunden til man indtager C-vitamin er, at det er en antioxidant, der hjælper med at eliminere "free radicals"/affaldsstoffer og cortisol i musklerne, stoffer som kun har negativ effekt på genopbygningen af muskelfibre.

Det giver ikke megen mening - fordi du ikke definerer affaldsstoffer, og fordi vitamin c ikke "fjerner cortisol fra musklerne".

Cortisol er et livsnødvendigt stress hormon, der måske set med pumper-øjne er noget ubrugeligt bras, men uden det ville mennesket hverken være i stand til at kapere emotionelt eller fysisk stress - den cirkulerende cortisolkoncentration varierer cirkudiant på lige fod med andre stoffer som hGH som en del af den menneskelige homeostase, det er ikke et affaldsstof.

Når cortisol cirkulerer rundt i blodbanen optages stoffet passivt i forskellige celler, da cortisol som steroid hormon har den unikke evne til at passere cellemembranen passivt (modsat fx glukose), inde i cellens cytosol bindes den til et transportermolekyle der tillader den passage ind i cellens kerne, hvorefter cellens transkription af forskellige proteiner reguleres på DNA niveau - vitamin C påvirker på ingen måde cortisols rolle som transkriptionsfaktor, eller nedbryder denne.

Noget andet er kraftig træning, ved længerevarende træning dannes store mængder af katekolaminer fra binyremarven, til denne syntese skal der, som jeg skrev i min første post, bruges vit. c, koncentrationen af denne falder derfor umiddelbart efter længere tids varende hård træning - som jeg har forstået hypotesen er dette grunden til at nogle mener at en øget koncentration af vit. c i blodet kan formindske stigningen i cortisol. Dit abstract synes at vise at dette også er tilfældet - men du bør måske lige nævne at diskussionen om hvorvidt ascorbinsyre som supplement kan sænke post-exercise koncentrationen af cortisol er noget der stadig er på hypotese planet, for at understreege dette fandt jeg en anden undersøgelse:

Jeg fandt desuden en interessant artikel

Det viser sig her, at selvom store doser af vit. c initialt sænker cortisolproduktionen, så stiger den senere, faktisk til et højere niveau end før, dette som baggrund i at faldet i cortisol initialt stimulerer ACTH på hypothalamus niveau, faktisk så meget at forskerne bag mener at vitamin c muligvis kan bruges til at dæmpe et eventuelt autoimmunt respons - det er da meget komisk, ikk?

og skulle det så vise sig, når der engang kommer en stor metaanalyse på området, at vitamin c tilskud kan reducere cortisol en smule ved ekstrem intensiv fysisk aktivitet, kan man så overveje om det i sig selv gør det fordelagtigt nok at spise vitamin c dagligt - også i lyset af hvor hurtigt post-exercise stigninger i cortisol falder igen.

Har kun lige haft tid til at skimme din tekst. Læser den igennem grundigt i morgen for at kunne give dig et svar. Ser udmiddelbart ud til, at du har fat i noget.

[RunnersHigh]

Her er lidt læsestof:

How Does Vitamin C Function in the Body?

"Much like the immune system itself, which operates at a cellular level,the hardworking vitamin C reaches every cell of the body. The concentration of vitamin Cin both blood serum and tissues is quite high.1In fact, this nutrient plays a major role in the manufacture and defense of our connectivetissue, the elaborate matrix that holds the body together. It serves as a primaryingredient of collagen, a glue-like substance that binds cells together to form tissues.

Vitamin C helps some of our most important body systems. First and foremost, ithelps the immune system to fight off foreign invaders and tumor cells. Vitamin C alsosupports the cardiovascular system by facilitating fat metabolism and protecting tissuesfrom free radical damage, and it assists the nervous system by converting certain aminoacids into neurotransmitters.

The skin, teeth and bones also benefit from vitamin C's collagen-forming andinvader-resisting properties; this vitamin contributes to the maintenance of healthybones, the prevention of periodontal disease and the healing of wounds. It even serves asa natural aspirin, of sorts, by combating inflammation and pain, according to FormulaFor Life. It accomplishes this task by inhibiting the secretion of theprostaglandins that contribute to such symptoms.2

What Biochemical Processes Require Vitamin C?

Collagen metabolism. . Most of us know collagen as the much-promotedingredient in our facial moisturizers and hand lotions. But the use of collagen in beautyand skin products only hints at the importance of this protein. The very structure of thebody - the skin, bones, teeth, blood vessels, cartilage, tendons and ligaments - dependson collagen. And the integrity of collagen, in tum, depends on vitamin C.

In a report on ascorbic acid in Vitamin Intake and Health, S.K. Gabyand V.N. Singh explain that collagen protein requires vitamin C for"hydroxylation," a process that allows the molecule to achieve the bestconfiguration and prevents collagen from becoming weak and susceptible to damage. Beyondthat, they say, recent evidence indicates that vitamin C increases the level ofprocollagen messenger RNA. "Collagen subunits are formed within fibroblasts asprocollagen, which is excreted into extracellular spaces. Vitamin C is required to exportthe procollagen molecules out of the cell. The final...structure of the collagen is formedafter pieces of the procollagen are enzymatically cleaved," state Gaby and Singh.3

Antioxidant functions. As a water-soluble antioxidant, vitamin C is in aunique position to "scavenge" aqueous peroxyl radicals before these destructivesubstances have a chance to damage the lipids. It works along with vitamin E, afat-soluble antioxidant, and the enzyme glutathione peroxidase to stop free radical chainreactions.

Immune system functions. Vitamin C can enhance the body's resistance toan assortment of diseases, including infectious disorders and many types of cancer. Itstrengthens and protects the immune system by stimulating the activity of antibodies andimmune system cells such as phagocytes and neutrophils.4

Other processes. Vitamin C contributes to a variety of other biochemicalfunctions. These include the biosynthesis of the amino acid carnitine and thecatecholamines that regulate the nervous system. It also helps the body to absorb iron andto break down histamine, the inflammatory component of many allergic reactions.5

What Specific Locations in the Body does Vitamin C Affect?

Although vitamin C is found in every cell, it is especially useful in keyparts of the body. These include the blood, the skin, the nervous system, the teeth andbones and glands such as the thymus, adrenals and thyroid.

What Foods are Good Sources of Vitamin C?

Large concentrations of vitamin C can be found in fruits such as oranges,grapefruits, tangerines, lemons, limes, papaya, strawberries and cantaloupe. Vitamin C andbioflavonoids - the watersoluble substances that help to protect your capillaries - arefound in the white linings of these and other plants. Many vegetables also pack in vitaminC including tomatoes, broccoli, green and red bell peppers, raw lettuce and other leafygreens.

How Is It Absorbed in the Body?

Species that make their own vitamin C synthesize it in the liver fromglucose. Unfortunately, humans must get their ascorbic acid from dietary sources. VitaminC is absorbed by an active transport system located in the gut and then reabsorbed throughthe kidneys, explain Gaby and Singh. Since the absorption mechanisms in the gut andkidneys can reach a saturation point, it is better to take multiple doses of vitamin Cthroughout the day than one large dose.6

How Much Vitamin C is Needed to Prevent a Deficiency?

The classic deficiency state related to vitamin C is scurvy, a conditioncharacterized by gum disease, pain in the muscles and joints, skin lesions, fatigue andbleeding. An adult needs 10 milligrams of vitamin C per day to prevent scurvy. This is theabsolute minimum, however, and some studies have shown that a daily dose of 100 mg or moremay be needed to maintain or maximize the body pool of vitamin C.7

Who is Likely to Require a Higher Quantity of Vitamin C?

Depending on genetics and life-style factors, some people may require morevitamin C than the average healthy adult to prevent the disruption of importantbiochemical reactions. The elderly, alcohol consumers, diabetics and smokers, for example,tend to be low in vitamin C. In their report, Gaby and Singh offer the following evidenceof this relationship.8

The elderly. Elderly people are known to be lacking in vitamin C,primarily because their diet is poor. In a 1978 study, elderly people had only half thelevel of ascorbic acid in their blood plasma as did younger subjects. How much vitamin Cdo they need to make up for this deficit? According to two studies, men and women over age65 need daily doses of 150 mg and 75 to 80 mg, respectively, to maintain a plasma level of1.0 mg/dl.

Alcohol consumers. Many chronic drinkers lack an adequate level of vitamin Cbecause they tend to eat poorly, according to Gaby and Singh. Research also shows that alarge intake of alcohol can depress the concentration of ascorbic acid in plasma andincrease urinary excretion of vitamin C. Therefore, one study suggests that doses ofvitamin C - at 500 to 1,000 mg per day can aid in the treatment of alcoholism.

Diabetics. The tissues and organs of diabetics may be deprived of vitaminC, requiring them to consume more of the nutrient than does the average person. Vitamin Cmust compete with glucose to reach the tissues and organs through a common cellulartransport system. An insufficient supply of insulin also can inhibit the transport ofvitamin C to cells that require insulin for their glucose uptake.

Workers exposed to toxins. Studies also show that the blood levels ofvitamin C may be low in workers who are exposed to occupational pollutants such as leadand coal tar.

Smokers. At this point, it is a well accepted fact in the scientific arenathat cigarette smoke has a negative impact on the metabolism of vitamin C. According tothe Journal of Clinical Nutrition, people who smoke have a much lower levelof ascorbic acid in the blood than do nonsmokers. While the Food and Nutrition Boardrecommends that smokers consume 100 mg of vitamin C a day, they may need 200 mg or more tomaintain the same concentration of serum ascorbate as a nonsmoker who gets 60 mg ofvitamin C per day.9

How Does Vitamin C Aid the Immune System Defenses?

Vitamin C assists the immune system in two of its primary functions to ridthe body of foreign invaders and to monitor the systems for any sign of tumor cells. Itaccomplishes these vital tasks by stimulating the production of white blood cells,primarily neutrophils, which attack foreign antigens such as bacteria and viruses. It alsoboosts the body's production of both antibodies and interferon, the protein that helpsprotect us from viral invaders and cancer cells.10

As a constituent of collagen, vitamin C may contribute to our immune defenses inan even more fundamental way: our skin and the epithelial lining of the body's orifices,both of which contain collagen, serve as our first line of defense against foreigninvaders.11 They prevent theseinvaders from entering the body in the first place, where the immune system would have togo to war against them.

Beyond that, vitamin C acts against the toxic, mutagenic and carcinogenic effectsof environmental pollutants by stimulating liver detoxifying enzymes. It also stimulatesthe production of PGE1, a prostaglandin which assists lymphocytes, the defender cells inour immune system.12

As the following studies demonstrate, vitamin C can enhance the immune functionin a number of ways:

Healthy adults. In a 1981 study, healthy adults received 1 gram of vitaminC intravenously. One hour later, the neutrophil motility and leukocyte transformation inthe subjects' blood had increased significantly. Other studies support the finding thatvitamin C enhances the leukocyte function. It has also been shown to decreasebacteriological activity.13

Chronically ill adults. Recent studies show that vitamin C has a positive effecton patients suffering from a variety of chronic disorders. In one large study, 260patients with viral hepatitis A took 300 mg of vitamin C a day for several weeks. Theresearchers, who studied immune indicators, such as serum immunoglobulin and neutrophilphagocytosis, concluded that vitamin C "exerts a remarkable immuno-modulatingaction."14

Likewise, a study of 14 patients with chronic brucellosis found that vitamin C"might partially restore peripheral, monocyte function and help themonocyte-macrophage system to mount an effective immune response against [the infection].15 In 60 patients with perennialallergic rhinitis, an ascorbic acid solution lessened symptoms in roughly three-fourths ofthe patients.16 And asthmaticpatients who were treated with vitamin C before their airway was constricted via exercisehad much less difficulty breathing.17

Test tube. The immune system process called phagocytosis, in which certain cells"eat" invading bacteria, is stimulated by vitamin C. In addition, the nutrientmay reduce the suppressor activity of the mononuclear leukocytes, which weakens theoverall effectiveness of the immune system.18

Animal studies. In one study of guinea pigs (which, like humans, cannotmanufacture their own vitamin C), the antibody to a particular antigen responded fasterwhen the animals received vitamin C. Meanwhile, a study of chickens analyzed their abilityto withstand E. coli challenge infection by taking 330 mg of vitamin C. Only 19% of thesupplemented animals got the infection, while 76% of the unsupplemented control subjectswere infected.19

As an Antioxidant, How Does Vitamin C Help to Protect the Body?

Vitamin C protects the DNA of the cells from the damage caused by freeradicals and mutagens. As Gaby and Singh report, it prevents harmful genetic alterationswithin cells and protects lymphocytes from mutations to the chromosomes. Vitamin C may beespecially important in this day and age of widespread environmental pollution because itcombats the effects of many such toxins, including ozone, carbon monoxide, hydrocarbons,pesticides and heavy metals.

It appears that vitamin C fights off these pollutants by stimulating enzymes inthe liver that detoxify the body. In several studies, vitamin C reduced chromosomeabnormalities in workers exposed to pollutants such as coal tar, styrene, methylmethacrylate and halogenated ethers. Another way in which vitamin C protects us is bypreventing the development of nitrosamines, the cancer-causing chemicals that stem fromthe nitrates contained in many foods.20

Vitamin C prevents free radical damage in the lungs and may even help to protectthe central nervous system from such damage.21In a study of guinea pigs, an ascorbic acid pretreatment effectively diminished the acutelung damage caused by the introduction of superoxide anion free oxygen radicals to thetrachea.22 Ascorbic acid also wastested as an antioxidant to inflammatory reaction in mice. High doses given after but notbefore the injury successfully suppressed edema.23

As an antioxidant, vitamin C's primary role is to neutralize free radicals. Sinceascorbic acid is water soluble, it can work both inside and outside the cells to combatfree radical damage. As explained earlier, free radicals will seek out an electron toregain their stability. Vitamin C is an excellent source of electrons; therefore, it"can donate electrons to free radicals such as hydroxyl and superoxide radicals andquench their reactivity," states Adrianne Bendich in "AntioxidantMicronutrients and Immune Responses".24

The versatile vitamin C also works along with glutathione peroxidase (a majorfree radical-fighting enzyme) to revitalize vitamin E, a fat-soluble antioxidant. Inaddition to its work as a direct scavenger of free radicals in fluids, then, vitamin Calso contributes to the antioxidant activity in the lipids.

How Much Vitamin C Is Needed for Antioxidant Activity?

Free radical pathology may occur when the body's antioxidant mechanismscannot keep pace with the rate at which free radicals and other oxidants are being formed.To supply the body with enough antioxidant power, R.F. Cathcart, a clinical practitionerwho has treated thousands of patients with vitamin C, believes each person should take thevitamin up to his or her "bowel tolerance" level. Simply put, this is the leveljust below the daily dosage that would cause you to have diarrhea.

As Dr. Jeffrey Bland reports in The Nutritional Effects of Free RadicalPathology, Cathcart believes that the more severe the toxicity from oxygen radicals,the more vitamin C one can tolerate. Therefore, your bowel tolerance level may be 10,000mg per day or more which should be taken in divided doses.25

Does Vitamin C Contribute to Cardiovascular Health?

As an antioxidant and a constituent of collagen, vitamin C may play anumber of roles in maintaining cardiovascular fitness. Here's how it affects someimportant aspects of cardiovascular functioning:

Atherosclerosis status. The fatty plaques that form in blood vessels,called atherosclerosis, are a major contributor to heart disease, Vitamin C may preventthis plaque formation by inhibiting the oxidative modification of low density lipoproteins(LDLs), according to a study conducted at the University of Texas Southwestern MedicalCenter. LDLs, commonly known as the "bad" form of cholesterol, may"contribute to the atherosclerotic process by its cytotoxic effects, uptake by thescavenger receptor and influence on monocyte and macrophage motility," say theresearchers.26

Beyond that, vitamin C may play a mitigating role in another aspect ofatherosclerosis - the buildup and adhesion of platelets on vessel walls. As Gaby and Singhreport, an injury to the vessel wall prompts the production of a prostaglandin calledthromboxane. This prostaglandin causes platelets to aggregate and clot. On the other hand,a prostaglandin called prostacyclin helps protect us against the effects of this process.

In human studies, vitamin C in doses ranging from 1 to 2 grams per day has beenshown to hinder platelet aggregation and adhesion, reduce the level of an oxidationby-product in platelets, and increase fibrinolytic activity, which may help to cleararteries. Animal studies have found that vitamin C can prevent or reverse the plaqueformation caused by a high-cholesterol diet, reduce platelet aggregation by stimulatingthe production of prostacyclin, and interfere in the platelet release mechanism, therebyreducing platelet activity.27

Serum lipid levels. By now, most of us know that too much cholesterol canlead to heart disease. However, studies on the relationship of vitamin C to bloodcholesterol levels report mixed results. According to Gaby and Singh, a few human studieshave noted a positive connection between the blood levels of vitamin C and high densitylipoproteins (HDLs). Unlike the LDLs, which can lead to plaque, HDLs help to reduce therisk of heart disease by "scavenging" cholesterol. Conversely, a number ofstudies on the vitamin C/cholesterol connection concluded that the vitamin did not have apositive effect on serum lipids. Gaby and Singh point out that most of these studies wereconducted with small groups of people for a short period of time.28

In one notable study, however, researchers monitored the cholesterol levels ofpeople who took 1,500 mg of vitamin C a day. They found that the cholesterol levels werereduced significantly because vitamin C encouraged the conversion of cholesterol into bileacids, which are then eliminated from the body in the feces, according to Formulafor Life.29 Similarly,several animal studies indicate that vitamin C contributes to this conversion bystimulating an enzyme that regulates the process. In addition, vitamin C may increase thebeneficial HDL cholesterol.30

Ischemic heart disease. When the blood supply to an organ is cut off, itdeprives the cells and tissues of oxygen and results in a harmful condition calledischemia. Like other antioxidants, vitamin C can protect the area of the heart that isdeprived of oxygen from further damage by free radicals.31

Do Any Disease States Respond to the Use of Vitamin C?

Cataract development As we age, the large concentration of ascorbicacid in the optic lens beings to decline. At the same time, the risk of developing acataract increases, in part from oxidative damage to the lens protein. As an antioxidant,vitamin C can defend the lens by hindering the destructive process of lipidphotoperoxidation, which clouds the vision.32In one national study of nutrition and disease, a reduced risk of age-relatedmacular degeneration was related to the frequency of consumption of fruits and vegetablesrich in vitamins A and C.33

Animal studies also show that vitamin C serves an important role in protectingthe lens. In guinea pigs subjected to heat-induced protein damage, for example, largeamounts of dietary ascorbic acid reduced the loss of water-soluble proteins in the lens,thereby protecting the eyes from this type of damage.34In another study, rats were exposed to selenite-induced cataracts, which result fromoxidative stress to the lens. The preventive effects of an ascorbate treatment weresignificant, supporting the researchers' view that vitamin C serves as an"anticataractogenic substance."35

Hemolytic and Sickle Cell Anemia. Vitamin C can do much to enhance thebody's absorption of iron, especially the "nonheme" variety found in plants anddrinking water ("heme" iron comes from meat). Ordinarily, our absorption of ironis quite poor, putting us at risk of iron-deficiency anemia. But a handful of studies havefound that 25 to 100 milligrams of ascorbic acid when taken with a meal, can double oreven triple nonheme iron absorption.36

Periodontal disease. Not surprisingly, the mouth is susceptible to manyinvading bacteria, which can plant themselves in dental plaque and lead to periodontaldisease. By improving the body's defense mechanisms, then, vitamin C can help to ward offbacterial infection and maintain periodontal health. Vitamin C may accomplish this task inseveral ways, including the stimulation of leukocyte and neutrophil chemotaxis andbactericidal activity.37,38

Remember, too, that vitamin C is a major constituent of collagen, which not onlypreserves the integrity of tissues but also supports the body's resistance to invadingmicrobes. In one study of people with damaged connective tissue in the gums, vitamin Csupplements of 70 mg per day increased intracellular linkages and collagen bundles. Inanother study, gum bleeding caused by a vitamin C deficiency was reduced by supplements ofthe nutrient, with greater results at 600 mg per day than at 60 mg.39

Bone disorders. By now, you probably get the point that vitamin C's rolein collagen formation is an important one. But if you're still not convinced, considerthis addition to the picture: Strong bones depend on strong collagen. As we age, however,both the density of our bones and our level of vitamin C begin to decrease. While a numberof factors contribute to osteoporosis (the loss of bone), studies show that a person'svitamin C status also is related to the maintenance of healthy bones. In fact, vitamin Cmay directly impact the growth of bone cells, above and beyond its call of duty in formingcollagen.

Osteoporosis occurs most often in older women, in part because estrogen appearsto help protect against bone loss. In several studies of postmenopausal women and a mixedpopulation, vitamin C intake was correlated with bone mineral content or bone density."Ascorbic acid intake at moderate doses is important and safe for bone maintenance,and therefore a factor in mitigating or delaying osteoporosis," say Gaby and Singh.40

What about the joints that connect our bones? Vitamin C may help here, too. Whenmice with arthritis and inflammation in their paws received vitamin C for 20 days, thetreatment reduced arthritic swelling, increased their pain tolerance and decreasedpolymorphonuclear leukocyte infiltration. The researchers concluded: "Vitamin C mayprovide podiatrists with a supplemental or alternative treatment for patients withrheumatoid arthritis."41Another study found that the rapid depletion of vitamin C at the site of an inflammation -such as a rheumatoid joint - may facilitate proteolytic damage.42

Diabetes. Diabetics tend to have low levels of vitamin C not only in theplasma but also in the white blood cells, which constitute our immune defenses. One study,conducted at the University of Massachusetts, measured the ascorbic acid content ofmononuclear leukocytes in adults with insulin-dependent diabetes mellitus. This contentlevel, which serves as a gauge of the vitamin C status of tissues, was reduced by 33% inthe diabetic patients, even though their intake of dietary vitamin C was adequate.According to the researchers, this impaired storage capacity "supports the theorythat intercellular scurvy contributes to the chronic degenerative complications of thedisease."43

Can Vitamin C help to Prevent or Treat Cancer?

Over the years, many studies have found that vitamin C is an effectiveanti-cancer agent. It works in the following ways to help the body combat cancer cells:

Studies suggest that vitamin C's antioxidant mechanisms may help to preventcancer in several ways. It combats the peroxidation of lipids, for example, which has beenlinked to the aging process and degeneration. One study of elderly people found that 400mg of vitamin C per day (for a one-year period) reduced serum lipid peroxide levels.Vitamin C can also work inside the cells to protect DNA from the damage caused by freeradicals. In several studies, report Gaby and Singh, vitamin C reduced the level ofpotentially destructive genetic alterations or chromosome aberrations.44

Many of the pollutants that now pervade our environment can cause toxic,carcinogenic or mutagenic effects. Vitamin C may be able to arrest these harmful effects,in part by stimulating detoxifying enzymes in the liver. In another study, vitamin C wasshown to block the formation of fecal mutagens.45

Vitamin C can help to optimize the immune system, which does the allimportant jobof surveying the body for the presence of cancer cells. According to Richard A. Passwater,Ph.D., it also enhances an intracellular material called ground substance that holdstissues together. When this substance is strong, cancer cells have a harder timeinfiltrating cells.46

Finally, vitamin C can reduce the development of nitrosamines from nitrates,chemicals that are commonly used in processed foods. Once formed, nitrosamine can become acarcinogen. But in several human studies, in which the subjects consumed a nitrosamineprecursor, the urinary levels of nitrosamines were significantly reduced by vitamin C.47 Three animal studies also supportthe preventive effects of ascorbic acid on nitrate-induced cancer. In all three cases, theformation of tumors was inhibited, suppressed or reduced in frequency in the animalstreated with vitamin C.48-50

As far back as the late 1940s, researchers began to note a connection between theincidence of cancer and a dietary deficiency of vitamin C or low blood levels in the body.Studies conducted in the past decade have confirmed that link. According to two studiesfrom the early 1980s, 2 to 5 grams of vitamin C per day can correct these low serum levelsand, in some patients, improve the immune system defenses.51

At this point, it seems clear that there is a strong relationship between aperson's vitamin C intake and cancer risk. In 1991, the American Journal of ClinicalNutrition conducted a comprehensive analysis of some 46 studies on vitamin C'sprotective effects against various types of cancer. Of these, 33 studies reported asignificant link between vitamin C intake and the incidence of cancer. In fact, a highintake of vitamin C offered twice the protection of a low intake. Many of these studiesdefined a high intake as a daily dosage of 160 mg or more per day; a low intake generallywas less than 70 mg.52

According to author Gladys Block, the greatest effects were noted with cancer ofthe esophagus, larynx, oral cavity and pancreas, followed by cancer of the stomach,rectum, breast and cervix. While vitamin C's impact on lung cancer was less consistent,several studies did find significant protective effects. "The strength andconsistency of the results reported here for several sites suggests that there may be areal and important effect of ascorbic acid in cancer prevention," states Block.

Here, we summarize Block's findings regarding specific types of cancer, includingnon-hormone-dependent cancers (of the oral cavity, larynx, esophagus, lung, pancreas,stomach, colon and rectum) and hormone-dependent cancers (of the breast, ovaries,endometrium and prostate). In all cases, the studies either developed an index thatmeasured participants' vitamin C intake or reported on the effects of a vitamin C-richfood, primarily fruit, in the diet.53

Oral cavity, larynx and esophagus. All 8 studies reporting on a vitamin Cindex found that people with a low intake had a significantly greater risk of developingthese cancers. Meanwhile, six of the 12 studies of food intake rather than a nutrientindex found a significant risk for low fruit intake. Of the remaining six, two foundsuggestive results, two found low intakes in high-risk populations and one found noeffect.54

Lung. The lung cancer studies generated mixed reports on vitamin C. Of 11 suchstudies, five found a significant protective effect, four found protective but notsignificant effects and two found no effect. Interestingly, four studies reported thatvitamin C had stronger effects than carotenoids. "Whereas a large body of evidencesuggests an important effect for carotenoids in lung cancer prevention," says Block,"the recent data suggest that there may also be an independent protective effect ofvitamin C intake."55

Pancreas. In the one study that developed a vitamin C index, a high intakedecreased the risk of pancreatic cancer by half. Five studies also found that fruit (andvegetables in some cases) offered significant protective effects against this cancer,which is the fifth leading cause of cancer death in this country.56

Stomach. All seven studies on vitamin C intake and the risk of stomachcancer concluded that the nutrient's protective effects were significant. Of eight studiesthat analyzed fruit intake, all but one found that people with stomach cancer had a lowerconsumption of fruit.57

Colon and rectum. Of six studies on rectal cancer, four found that vitaminC offered significant protection and two found suggestive results. The results with coloncancer were less consistent. Four studies noted significant protection, two foundsuggestive effects and two studies that developed a nutrient index found no effect. One ofthese, however, reported that vitamin C-rich foods had a significant effect.58

Breast, ovary, endometrium and prostate. According to Block, recentevidence indicates that vitamin C may play an important role in protecting against breastcancer. But with endometrial, ovarian and prostate cancer, studies have not found thevitamin's effects to be significant.59

In 1976, Dr. Linus Pauling brought vitamin C into the limelight by reporting onthe results of his cancer research. In the study he conducted with Ewan Cameron, 100terminally ill cancer patients received 10 grams of vitamin C a day. As Dr. Passwaterreports in The Antioxidants, these patients lived more than four timeslonger than the 1,000 control subjects who did not receive vitamin C. Only three of these1,000 patients survived for more than a year, while 16 of the 100 patients taking vitaminC lived a year or longer.60

More recently, E. Cameron reported similar results from a study he conducted inAlexandria, Scotland, between 1978 and 1982. In this case he created a database to recordvarious details about every cancer patient who attended 3 hospitals in Scotland during thefour-year period.

The study included 1,826 "incurable" (in a total population of 2,804).Of the "incurable" patients, 294 had received supplemental ascorbate at somepoint during their illness. The remaining 1,532 patients, who did not take vitamin C,served as the controls. In analyzing the data, the researchers found that "theascorbate-supplemented patients had a median overall survival time (343 days) almostdouble that of the controls (180 days)."61

Still, other studies have found that large daily doses of vitamin C had no effecton advanced cancer or the survival rate of women with breast cancer. "Currentevidence suggests that the major benefit of ascorbic acid with regard to cancer may be inreducing the risk of developing cancer, rather than in therapy," state Gabyand Singh.62

Does Vitamin C Function Synergistically With Other Nutrients?

As an antioxidant, vitamin C can rejuvenate vitamin E, making it anindirect contributor to the fight against free radical damage in the lipids. It's notsurprising, then, that these two nutrients can be effective partners in reducing thedestructive process of lipid peroxidation. In human and animal studies, this reductiontook place in subjects with diabetes, cerebral arteriosclerosis or a heart disorder.63-65 Together, vitamins C and E canhelp to prevent the blood from clotting, a condition that contributes to the risk ofstroke.66 This combination may offerprotection against cataracts as well.67

The synergistic combination of vitamins C and E may be further enhanced by theaddition of vitamin A. In one study of 30 elderly long-stay patients, for example, thistrio was effective in improving certain aspects of cell-mediated immunity, such as thenumber of T cells, T4 subsets and the ratio of T4 to T8 cells.68In another study, a complex of vitamins A, E and C significantly enhanced the"characteristics of enzymatic and non-enzymatic antioxidant protection of theliver" in mice.69 Finally, aclassic antioxidant combination - vitamins C and E, beta carotene and selenium - helped toalleviate pancreatitis, or an inflammation of the pancreas, in a study of 28 patients.

Is There Any Evidence that Vitamin C has Harmful Side Effects?

Over the years, vitamin C has been blamed for a number of harmful sideeffects, generating much controversy about the safety of the nutrient. But most of theseclaims are undeserved. "Apparently, vitamin C has a low order of toxicity, orintoxications would be common. Although large intakes may cause adverse effects in someindividuals, some of the widely reported and often cited adverse effects have littleapparent basis," states John Hathcock in "Safety of Vitamin and MineralSupplements."

Three of the most serious side effects that have been attributed to vitamin C areconditioned scurvy, kidney stones and the destruction of vitamin B12. But in analyzing thestudies that reported on the relationship between vitamin C and these health problems,Hathcock has found that there is no real clinical evidence to support the idea thatvitamin C is responsible for any of these conditions.

One common complaint regarding vitamin C is that it can cause gastrointestinaldistress, including cramps, diarrhea and nausea. These symptoms, which are caused by theacidity rather than the ascorbate itself, seem to disappear when a buffered form ofvitamin C is taken. In some cases, the chewable form of vitamin C also has led to erosionof dental enamel. In facilitating the absorption of iron, vitamin C can decrease theintake of copper and lead to a "negative copper balance," says Hathcock."

Gary Null, Ph.D.

References

1. Eberhard Kronhausen and Phyllis Kronhausen with Harry B. Demopoulos, M.D., Formulafor Life, William Morrow and Co., New York, 1989, p. 95.

2. Ibid, p. 102.

3. S.K. Gaby and V.N. Singh, "Vitamin C," – Vitamin Intake andHealth: A Scientific Review, S.K. Gaby, A. Bendich, V. Singh and L. Machlin (eds.)Marcel Dekker, N.Y. 1991 p. 103-1043.

4. Kronhausen. p. 96.

5. Gaby, p. 103-104.

6. Ibid, p. 105.

7. Ibid, p. 104-105.

8. Gaby, p. 105-108. sg

9. Gordon Schectman, James C. Byrd and Raymond Hoffmann, "Ascorbic AcidRequirements for Smokers: Analysis of a Population Survey, American Joumal of ClinicalNutrition, 1991; 53:1;1466-70.

10. Kronhausen, p. 96.

11. Gaby, p.120.

12. Kronhausen, p. 102.

13 Gaby, p. 120-121.

14 V.S. Vasil'ev, V.l. Komar and N.l. Kisel, "Humoral and Cellular Indices ofNonspecific Resistance In Viral Hepatitis A and Ascorbic Acid, Ter-Arkh; 1989 61(11); p.44-6.

15. P. Boura at al., "Monocyle Locomotion In Anergic Chronic Brucellosis Patients:The In Vivo Effect of Ascorbic Acid," Immunopharmacol-lmmunoloxicol; 1989;11(1): p. 119-29.

16. L. Podoshin, R. Gertner and M. Fradis, "Treatment of Perennial Allergic Rhinoswith Ascorbic Acid Solution," Ear-Nose-Throat J.; January 1991; 70(1); p.54-5.

17. M. Miric and M.A. Haxhiu, Effect of Vitamin C on Exercise-inducedBronchoconstriction, Plucne-Bolesti; January-June 1991, 43(1-2); p. 94-7.

18. Gaby, p. 120.

19. W.B. Gross, D. Jones and J. Cherry, Effect of Ascorbic Acid on the Disease Causedby Escherichia Coli Challenge Infection," Avian-Dis.; July-September, 1988;32(3); p. 407-9.

20. Gaby, p. 108-109.

21. Kronhausen, p. 104.

22. G. Becher and K. Winsel, "Vitamin C Lessens Superoxide Anion(02)-lnducedBronchial Constriction," Z-Erkr-Atmungsorgane; 1989; 173 (10): p. 100-4.

23. C.R. Spillert et al., "Inhibitory Effect of High Dose Ascorbic Acid onInflammatory Edema," Agents-Actions; June 1989; 27(3-4); p. 401-2.

24 . Adrianne Bendich , "Antioxidant Micronutrients and Immune Responses," Micronutrientsand Immune Functions, A. Bendich and R.K. Chandra (eds.) New York Academy of Sciences,New York, 1990, p. 175.

25. Jeffrey Bland, Ph.D., The Nutritional Effects of Free Radical Pathology: 1966/AYear in Nutritional Medicine, Keats Publishing Inc., New Canaan, CT; 1986; p. 16.

26. Ishwaral Jialal, Gloria Lena Vega and Scott M. Grundy, "Physiologic Levels ofAscorbate inhibit the Oxidative Modification of Low Density Lipoprotein,"Atherosclerosis; 82, 1990 p. 185.

27. Gaby, p. 125.

28. Ibid, p. 123-124.

29. Kronhausen, p. 96.

30. Gaby, p. 123.

31. Kronhausen, p. 103.

32. Gaby, p. 130-131.

33. J. Goldber et al., "Factors Associated with Age-Related MacularDegeneration," Am. J Epidemiol.; October 1988; 128(4); p. 700-10.

34 C.S. Tsao, L.F. Xu and M. Young, "Effect of Dietary Ascorbic Acid onHeat-lnduced Eye Lens Protein Damage in Guinea Pigs," Opthalmic, Res.; 1990;22(2); p. 106-10.

35. P.S. Devamanoharan et al., "Prevention of Selenite Cataract by Vitamin C,"Exp. Eye Res.; May 1990; 52(5); p. 563-8.

36. Gaby, p. 131.

37. Ibid, p. 134-135.

38. A. B. Rubinoff et al., "Vitamin C and Oral Health," J. Can. Den. Assoc.;September 1990; 55(9); p. 705-7.

39. Gaby, p. 135.

40. Ibid, p. 134.

41. R.H. Davis et al. "Vitamin C Influence on Localized Adjuvant Arthritis J. Am. Podiatr.Med. Assoc.; August 1990; 80(8); p. 414-8.

42. B. Halliwell et al.; "Biologically Significant Scavenging of theMyeloperoxidase-Derived Oxidant hypochlorous Acid by Ascorbic Acid," FEBS. lett.;March 9, 1987; 213 (1); p. 15-7.

43. J.J. Cunningham et al., "Reduced Mononuclear Leukocyte Ascorbic Acid Contentin Adults with Insulin-Dependent Diabetes Consuming Adequate Dietary Vitamin C;" Metabolism;February 1991; 40(2); p. 146-9.

44. Gaby, p. 108.

45. Ibid, p. 108 & 110.

46. Richard A. Passwater, The Antioxidants, Keats Publishing, Inc., New Canaan,CT, 1985, p. 13-15,

47. Gaby, p. 109.

48. F.K. Dzhioev, "Prevention Using Ascorbic Acid, Hexamethylenetetramine andSodium Metabisulfite of the Blastomogenic Effect Caused by the Combined Administrationinto the Stomach of Mice of Sodium Nitrate with Methylurea or with Aminopyrene," Vopr.Onkol.; 1988; 34(11); p. 1369-73.

49. S. Dittrich et al., "Effects of Nitrate and Ascorbic Acid on Careinogenesis Inthe Operated Rat Stomach," Arch. Geschwulstforsch; 1988; 58(4); p. 235-42.

50. N.L. Viasenko et al., "Effect of Different Doses of Ascorbic Acid on theInduction of Tumors with N-nitroso Compound precursors in Mice," Vopr. Onkol.; 1988;34(7); p. 839-43.

51. Gaby, p. 109.

52. Gladys Block, "Vitamin C and Cancer Prevention: The EpidemiologicEvidence," American Journal of Clinical Nutrition; 1991; 53:270S-82S.

53. Ibid, p. 270S.

54 Ibid, p. 271S-272S.

55. Ibid p. 272S-273S.

56. Ibid p. 273S.

57. Ibid, 273S-274S.

58. Ibid., 275S-276S.

59. Ibid, 276S-278S.

60. Passwater, p. 14.

61. E. Cameron and A. Campbell, "Innovation vs. Quallity Control: An‘Unpublishable' Clinical Trial of Supplemental Ascorbate in Incurable Cancer,"Med. Hypotheses; Nov. 1991; 36(3); p. 185-9.

62. Gaby, p. 117.

63. K.G. Karagezian and D.M. Gevorkian, "Phospholipid-Glycerides, Cross-Resistanceof Erythrocytes, Malonic Dialdehyde Level and Alpha-Tocopherol Levels in the Plasma andErythrocytes of Rats with Alloxan Diabetes Before and After Combined AntioxidantTherapy," Vopr. Med. Khim; September-October 1989; 35(5); p. 27~30.

64. V.N. Bobyrev, I. Sh. Vese'lskil and L.E. Bobyreva, "Antioxidants in thePrevention and Treatment of Cerebral Arteriosclerosis," Zh. Nevrapatol.Psikltatr.; 1989; 89(9); p. 60-3.

65. E. Barta et al., "Protective Effects of Alpha-Tocopherol and L-AscorbicAcid Against the Ischemic Reperfusion Injury in Patients During Open-Heart Surgery,"Bratisl. Lek. Listy.; March-April 1991; 92(3-4); p. 174-83.

66. Kronhausen, p. 103.

67. J.M. Robertson et al., "A Possible Role for Vitamins C and E In CataractPrevention," Am. J. Clin. Nutr.; January 1991; 53 (1 Suppl.); p. 346S-351S.

68. N.D. Penn et al., "The Effect of Dietary Supplementation with Vitamins A, Cand E on Cell-Mediated Immune Function In Elderly Long-Stay Patients: A RandomizedControlled Trial," Age-Aging, May 1991; 20(3); p. 169-74.

69. V.A. Kuvshinnikov et al., "Use of the Antioxidant Complex of Vitamins A, E andC In Murine Leukemia," Gematol. Transvuziol.; August 1989; 34(8): p. 23-8.

[ptpoul]

Mikael<<

Det er faktisk meget vigtigt hvilken form for stress man har været under.

Aerob træning og styrketræning stiller meget forskellige krav til restitution og stresser kroppen meget forskelligt.

Derfor kan man heller ikke forvente at man vil se ens reaktioner på de forskellige former for stress.

Derudover betyder mindre cortisol ikke nødvendigvis en bedre restitution.

De "katabolske" hormoner dæmoniseres ofte af bodybuildere. De er nødvendige og er måske endda en del af den stimulus der skal til for at sikre senere superkompensation?

Derfor er det vigtigt at se på om et givent tilskud giver egentlig forbedring af restitution for ens specifikke sportsgren.

Da bopdybuilding og ekstrem landistansceløb er så voldsomt forskellige og studiet ikke har vist nogen forskel på restitutionen kan jeg kun betegne studiet som irrelevant for os.

[-Elvirus-]

Som tilføjelse til Pouls indlæg, nu snakken falder på cortisol, synes det MINDST lige så vigtigt at betragte cortisol i sammenhæng med testosteron, hvorved ration mellem disse synes vigtigere end de absolutte værdier. Så hormon spejlet ved aktivitet skal nok nærmere betragtes i helhed, fremfor at fokusere på enkelt værdier.

Ligeledes, som Poul også nævner, har Cortisol en række andre og vigtige funktioner, såsom at medvirke til et øget blodflow til de arbejdene muskler, ved, sammen med en række andre hormoner (catecholaminerne), at skære på blodforsyningen til eksempelvis fordøjelsen.

Summa Summarum er kompleksiteten ved hormon respons på forskellige former for arbejdsstimuli enormt stor.

PS: RH, ingen gider at læse 345 siders copy/paste, du må gøre lidt arbejde og trække det du ønsker at sige med din post ud selv.

Edited November 15, 2006 by -Elvirus-

[RunnersHigh]

PS: RH, ingen gider at læse 345 siders copy/paste, du må gøre lidt arbejde og trække det du ønsker at sige med din post ud selv.

Jeg gider som regel heller ikke læse dine poster, men hvis nu du gad at læse min ville du finde et fremragende sammendrag af c-vitamins funktion i kroppen.

[Sindbad]

Her er lidt læsestof:

En masse tekst her

Gary Null, Ph.D.

References

69 referencer

Gary Null

Ikke at det betyder at ovenstående ikke er rigtigt - men det skal måske læses med en smule kildekritik (hvilket du jo altid gør RH ).

Sindbad

[kahlua-kalv]

Gary Null

Ikke at det betyder at ovenstående ikke er rigtigt - men det skal måske læses med en smule kildekritik (hvilket du jo altid gør RH ).

Sindbad

Touché, Runnerslow!

[Antaeus]

Gary Null

Ikke at det betyder at ovenstående ikke er rigtigt - men det skal måske læses med en smule kildekritik (hvilket du jo altid gør RH ).

Sindbad

Lad os opgradere "en smule kildekritik" til en rigtig stor portion kildekritik.

Det er jo bare en masse positive fund i en masse artikler som hives ud og beskrives uden nogen form for balancering af hvad der ellers findes af videnskabelig litteratur. Ligner noget der er skrevet for at sælge C-vitamin.

[RunnersHigh]

Gary Null

Ikke at det betyder at ovenstående ikke er rigtigt - men det skal måske læses med en smule kildekritik

God pointe Sinbad (hvilket du jo altid har )

Er enig i begge dine pointer. Både at det ikke nødvendigvis er forkert, og at det - som alt andet - skal læses med kildekritik.

Lad os i denne forbindelse ihukomme at begge lejre i C-vitamin-debatten - som i så mange andre debatter - har en tendens til at fremhæve kilder til støtte for deres position; jeg, du eller andre ikke undtaget.

Derfor skal Nulls kritiker (e.g. dit link) også læses med kritiske øjne. Når alt kommer til alt har alle en dagsorden ligegyldig hvilken side af hegnet de står på

Edited November 16, 2006 by RunnersHigh

[RunnersHigh]

Lad os opgradere "en smule kildekritik" til en rigtig stor portion kildekritik.

Det er jo bare en masse positive fund i en masse artikler som hives ud og beskrives uden nogen form for balancering af hvad der ellers findes af videnskabelig litteratur. Ligner noget der er skrevet for at sælge C-vitamin.

Jamen lad os da høre!

Kom frisk med en afbalancering af alle de "positive fund" om c-vitamin.

Du kan jo starte at afbalancere:

1. At c-vitamin er ganske central i collagen-dannelse

"The very structure of the body - the skin, bones, teeth, blood vessels, cartilage, tendons and ligaments - dependson collagen. And the integrity of collagen, in turn, depends on vitamin C."

2. At c-vitamin er en kraftig anti-oxidant

"Antioxidant functions. As a water-soluble antioxidant, vitamin C is in aunique position to "scavenge" aqueous peroxyl radicals before these destructive substances have a chance to damage the lipids. It works along with vitamin E, a fat-soluble antioxidant, and the enzyme glutathione peroxidase to stop free radical chainreactions."

3. At c-vitamin styrker immunforsvaret

"It strengthens and protects the immune system by stimulating the activity of antibodies and immune system cells such as phagocytes and neutrophils"

4. At c-vitamin er vigtig for en række andre biokemiske processer

"Vitamin C contributes to a variety of other biochemical functions. These include the biosynthesis of the amino acid carnitine and the catecholamines that regulate the nervous system. It also helps the body to absorb iron andto break down histamine, the inflammatory component of many allergic reactions"

Jeg glæder mig til at høre dig afbalancere ovenstående 4 punkter. Da det jo tilsyneladende ikke er andet end "positive fund" skulle det være en smal sag for dig at finde publiceret forskning der afbalancerer det.

Edited November 16, 2006 by RunnersHigh

[Sindbad]

God pointe Sinbad (hvilket du jo altid har )

Er enig i begge dine pointer. Både at det ikke nødvendigvis er forkert, og at det - som alt andet - skal læses med kildekritik.

Lad os i denne forbindelse ihukomme at begge lejre i C-vitamin-debatten - som i så mange andre debatter - har en tendens til at fremhæve kilder til støtte for deres position; jeg, du eller andre ikke undtaget.

Derfor skal Nulls kritiker (e.g. dit link) også læses med kritiske øjne. Når alt kommer til alt har alle en dagsorden ligegyldig hvilken side af hegnet de står på

Nu er jeg generelt skeptisk af natur - også overfor quackwatch.com.

Og i denne debat er jeg vist ikke på nogen sider af hegnet. Jeg er ikke engang på marken - jeg kører bare forbi på cykel...

Sindbad

[Stubbe]

Jamen lad os da høre!

Kom frisk med en afbalancering af alle de "positive fund" om c-vitamin.

Du kan jo starte at afbalancere:

1. At c-vitamin er ganske central i collagen-dannelse

"The very structure of the body - the skin, bones, teeth, blood vessels, cartilage, tendons and ligaments - dependson collagen. And the integrity of collagen, in turn, depends on vitamin C."

2. At c-vitamin er en kraftig anti-oxidant

"Antioxidant functions. As a water-soluble antioxidant, vitamin C is in aunique position to "scavenge" aqueous peroxyl radicals before these destructive substances have a chance to damage the lipids. It works along with vitamin E, a fat-soluble antioxidant, and the enzyme glutathione peroxidase to stop free radical chainreactions."

3. At c-vitamin styrker immunforsvaret

"It strengthens and protects the immune system by stimulating the activity of antibodies and immune system cells such as phagocytes and neutrophils"

4. At c-vitamin er vigtig for en række andre biokemiske processer

"Vitamin C contributes to a variety of other biochemical functions. These include the biosynthesis of the amino acid carnitine and the catecholamines that regulate the nervous system. It also helps the body to absorb iron andto break down histamine, the inflammatory component of many allergic reactions"

Jeg glæder mig til at høre dig afbalancere ovenstående 4 punkter. Da det jo tilsyneladende ikke er andet end "positive fund" skulle det være en smal sag for dig at finde publiceret forskning der afbalancerer det.

Hvor er det du vil hen med dit indlæg? Der er næppe nogen som betvivler C-vitamins effekter i kroppen eftersom det er et essentielt stof. Pointen er blot at mere ikke nødvendigvis er bedre. Det er det som diskutionen kører på - ikke om C-vitamin har positive effekter i kroppen.