Vitamin C is an essential vitamin with antioxidant properties. It is frequently supplemented to ward off the common cold.
Our evidence-based analysis features unique references to scientific papers. Each member of our research team is required to have no conflicts of interest, including with supplement manufacturers, food companies, and industry funders. The team includes nutrition researchers, registered dietitians, serum half-life vitamin and mineral supplements, physicians, and pharmacists. We have a strict editorial process.
This page features references. All factual claims are followed by specifically-applicable references. Click here to serum half-life vitamin and mineral supplements the full set of references for this page. Vitamin C, or L-ascorbic acid, is a water-soluble essential vitamin. It is a very popular dietary supplement due to its antioxidant properties, safety, and low price.
However, vitamin C is unable to reduce the frequency of colds in a healthy population. An athlete supplementing vitamin C, on the other hand, can expect to cut the risk of getting a cold in half. Though superloading vitamin C g daily is said to be more effective, further research is needed to determine the accuracy of this claim.
Vitamin C is capable of being both an antioxidant and pro-oxidant, depending on what the body needs. This mechanism allows it to serve a variety of functions in the body. Vitamin C sequesters free radicals in the body. It is replenished by antioxidant enzymes, and is often used as a reference drug in antioxidant research. Its antioxidant properties mean vitamin C provides neuroprotective effects and benefits for blood flow.
By protecting the testes from oxidative stress, vitamin C can also preserve testosterone levels. Ascorbic Acid, Ascorbate, 2-oxo-L-threo-hexono-1, 4-lactone-2, 3-enediol, L-ascorbic acid. L-Threonic Acid a metabolite. Zinc and Iron may enhance absorption. Superloading vitamin C, particularly via intravenous injections, has repeatedly been demonstrated in case studies to cause oxalate nephrotoxicity.
This is treatable potentially lethal if not treated and may be a reason to avoid injections of vitamin C if not supervised by a medical doctor. This is easily attained through the diet, so supplementation of such low doses is usually unnecessary. Higher doses of vitamin C, up to 2,mg, are used to support the immune system for serum half-life vitamin and mineral supplements or reduce the duration of the common cold.
Most studies on vitamin C prescribe one dose per day. The claim that taking 2,mg up to five times a day to optimally reduce cold symptoms is not sufficiently tested and requires more evidence. The Human Effect Matrix looks at human studies it excludes animal and in vitro studies to tell you what effects vitamin c has on your body, and how strong these effects are. Confounded with zinc . Serum half-life vitamin and mineral supplements C officially known as L-ascorbic acid, its prolonged name being 2-oxo-L-threo-hexono-1,4-lactone-2,3-enediol is an Essential Vitaminfirst structurally identified by Szent-Gyorgyi, Waugh, and King in   and first synthesized by Haworth and Hirst in Vitamin C is most commonly supplemented because of its potential protection against the common cold,  and purported anticancer effects.
The current recommendations for Vitamin C intake according to the FDA appears to be mg daily females and males, respectively for adults with increases of 10mg for pregnancy, 45mg for lactation, and 35mg for smokers. Vitamin C appears to be a cofactor for proper collagen synthesis, L-carnitine biosynthesis interestingly not mandatory and some neurotransmitters particularly catecholamines. Biosynthesis of Vitamin C can normally occur from either glucose or galactose being converted to glucosephosphate, which then is converted to uridine diphosphate glucose and via uridine diphosphate glucuoronic acid into L-glucuronic acid, serum half-life vitamin and mineral supplements.
Due to the weight loss centers and spas serum half-life vitamin and mineral supplements synthesize Vitamin C, it needs to be obtained via the diet.
A failure to get sufficient Vitamin C in the diet results in scurvy,   and the ability of a molecule to prevent scurvy of which Vitamin C is the reference drug serum half-life vitamin and mineral supplements known as being anti-scorbutic. This includes fever and viral infections, serum half-life vitamin and mineral supplements, stress, alcoholism,  smoking,   type II diabetes   despite consuming adequate vitamin C,  and in persons who have very recently suffered a myocardial infarction   or acute pancreatitis these last two normalizing after some time.
It has been noted  that it is still unclear whether the disease state causes a serum half-life vitamin and mineral supplements in vitamin C or vice versa vitamin C depletion exacerbates the progression of the above states or whether it is merely a biomarker of a poor diet this is seen in smokers  ; at least in myocardial infarction  and acute pancreatitis,  there is a drastic increase in oxidation rapidly and both diabetes  and smoking  are associated with elevated chronic oxidation.
Vitamin C appears to stable in food as the form of L-ascorbic acid in the pH range of . It is touted to be non-acidic and may be better tolerated by persons with acid reflux, as one study in persons sensitive to acidic foods noted that while Beyond this, Ester-C appears to be more effective at treating scurvy Vitamin C deficiency  and at decreasing oxalate levels a metabolite of Vitamin Serum half-life vitamin and mineral supplements  Ester-C has been reported to reduce the common cold, but was not compared to basic Vitamin C and has not been replicated.
Studies conducted using Ester-C that have been funded by Zila Nutraceuticals are cited following this sentence. Supplemental ascorbate appears to follow a dual phase pharmacokinetic profile. When serum levels are below within the physiological range the body serum half-life vitamin and mineral supplements to regulate ascorbate via resorption in the kidneys via sodium dependent vitamin C transporters  and have a prolonged half-life of days.
Oral intake of 1,mg vitamin c is able to increase plasma vitamin C to Supplementation of mg Vitamin C twice daily appears to increase expression of the transporter that mediates uptake of vitamin C in skeletal muscle SVCT2 and subsequently Vitamin C concentrations after one week, maintaining over 42 days of supplementation, despite no alterations in oxidative balance. Vitamin C appears to be metabolized into primarly one of three metabolites after it turns into a free radical ascrobyl radical ; dehydroascorbic acid, 2,3-diketogulonic acid and oxalic acid which convert into one another in that order.
Dietary supplementation does not necessarily increase urinary levels of these metabolites, as there is a lack of metabolism of L-ascorbic acid before it is urinated out, serum half-life vitamin and mineral supplements. As the first stage of metabolism is turning into a free radical, conditions characterized by excessive oxidation deplete circulating L-ascorbic acid which acts in a protective but sacrifical manner ; this is best shown with studies on smoking   which usually requires a higher Vitamin C intake.
Within the brain, Vitamin C appears to be in highest concentrations in the hippocampus, parietal cortex, and the cerebellum    with slightly lower concentrations in the frontal cortex, thalamic nuclei, olfactoy bulb, and striatum with lowest detected in the spinal cord and pons lowest. In isolated rat synaptic vesicles, vitamin C appears to cause acetylcholine release with an EC 50 value of Vitamin C has been found to, in vitroprotect cerebellar granule cells from glutamate induced excitotoxicity   which is thought to be related to how NDMA receptors can respond to REDOX modulation.
There appears to be an increase in oxidative stress within cells following percieved stressors both physical  and mental  and this increased oxidative state is known to lead to cellular death. Vitamin C appears serum half-life vitamin and mineral supplements have antidepressant effects, associated with potassium channels can be read up on under the depression section on the agmatine page.
In humans, there is an old case study where depression in a child induced by ACTH administration was alleviated with vitamin C  but more importantly, a study using a product known as Cetebe 3,mg vitamin C in otherwise healthy adults for two weeks noted a reduction in depressive symptoms Becks Depression Inventory and increase in the frequency of intercourse no influence on masturbation ;  this study was funded by the producer of Cetebe, GlaxoSmithKline.
There appear to be several disease states or metabolic conditions of which ascorbate deficiency in the endothelium is associated with endothelial dysfunction. The endothelial variant of the NOS enzyme eNOS appears to be susceptible to oxidative damage, serum half-life vitamin and mineral supplements, including both translation of the enzyme itself  and the required cofactor tetrahydrobiopterin is readily oxidized and rendered inactive.
Other possible mechanisms that may contribute also general to antioxidants include scavenging superoxide  which would otherwise reduce nitric oxide into peroxynitrate  and directly reducing nitrite product of nitrate into nitric oxide  or producing nitric oxide from S -nitrosothiols. Recent  research has shown that vitamin C interactions with glucose metabolism may make it useful as a potential anti-cancer agent.
Linus Serum half-life vitamin and mineral supplements,  later clinical trials failed to demonstrate any efficacy as a cancer treatment. This cast doubt on any anti-cancer properties for vitamin C, which was further reinforced by studies suggesting that antioxidants may actually give cancer cells an advantage by promoting, rather than inhibiting tumorigenesis.
At high doses vitamin C promotes, rather than reduces oxidative stress in cancer cells, leading to cytotoxic effects. The mechanism behind the selective toxicity of vitamin C against cancer cells was unknown until only recently, when a recent study found that vitamin C-induced oxidative stress inhibits GAPDH, an important metabolic enzyme in the glycolytic pathway. The main mechanism of concern with Vitamin C supplementation and muscle metabolism would be the antioxidant properties of Vitamin C,  although both the collagen and carnitine synthesis roles are thought to be useful.
The post exercise spike in cortisol is known to suppress activity of T-cells and B-cells, which would limit antibody production such as IgA. Although the combination of vitamin E and vitamin C can suppress IL-6 production in response to exercise,  this may or may not be helpful, given other work that suggesting that IL-6 may play a positive role in exercise adaptation.
For studies that measure upper respitatory tract infection risk following exercise, no significant effects are seen with 1,mg Vitamin C for 12 days prior to a simulated half marathon in the heat, serum half-life vitamin and mineral supplements. In contrast to the suppression of cortisol mentioned above with short term exercise, longer and more strenuous exercise such as ultramarathons are known to have an augmentation of cortisol with vitamin C.
DOMS is a soreness and tenderness of the muscle tissue that arises after exercise, serum half-life vitamin and mineral supplements, usually with a delay where it does not suface immediately but usually the next day or 48 hours afterwards. One study using Vitamin C at mg with Vitamin E at mg failed to notice any benefit to soreness with treatment relative to placebo.
Vitamin C mgin conjunction with Vitamin E mg as a mixed anti-oxidant supplement for 6 weeks in otherwise healthy men, is not significantly better than placebo at attenuating an exercise-induced reduction of power output seen during the recovery phase of exercise. There is mixed evidence in the literature on the effects of vitamin C on endurance performance.
It is generally accepted that the state of obesity, relative to a non-obese state, makes the same amount of exercise more tiring to the body perception and uses more caloric reserves for the same amount of serum half-life vitamin and mineral supplements. In another study, 11 health men took mg vitamin C twice daily along with IU vitamin E once daily or placebo for four weeks.
They were then subject to a strenuous 60 minute exercise routine on a stationary bicycle. The VO 2 peak of the vitamin group did not differ from placebo, nor did the rate of perceived exertion or maximal power output. Vitamin C has also been observed to decrease endurance performance in certain experimental models. One study noted that giving greyhounds 1g of vitamin C before racing significantly slowed racing time relative to dogs that did not receive supplementation.
On average, when dogs were supplemented with vitamin Ctheir m racing time was 0. While studies in greyhounds have limited relevance to humans, a later human study serum half-life vitamin and mineral supplements suggested that antioxidants may limit endurance in humans.
The study found that vitamin C suppressed endurance capacity, which was associated with a decrease in mitochondrial biogenesis,  driven by decreased expression of a number of different proteins important for the process. In subject that took a placebo, insulin sensitivity increased over the course of the training program. This occured in beginners as well as those with more extensive training experience.
At least one rat study notes that supplementation with Vitamin C 5mg is associated with an attenuation of bone loss due to ovariectomy, an animal model of menopause. It has been noted  that the observations from Linus Pauling on vitamin C interactions with the common cold may have been influenced by athletic cohorts, as one of the more convincing studies he wrote about  was in regards to children in a skiing school German PDF .
One study has noted that drug resistant Mycobacterium tuberculosis bacteria that causes tuberculosis is highly sensitive to being destroyed by Vitamin C, which was fairly unique as other bacteria tested were not affected, serum half-life vitamin and mineral supplements.
Vitamin C L-Ascorbic acid is a single electron donor, serum half-life vitamin and mineral supplements can be reduced into an ascorbyl radical AFR via either oxidative stressors or being used as a cofactor in enzymes. This scavenging applies to most reactive oxygen species ROS including superoxide O 2-  and some reactive nitrogen species such as peroxynitrate either directly  or reducing an O 2- induced conversion of nitric oxide into peroxynitrate.
It is wholly possible for Vitamin C to also act as a prooxidant depending on context, although the ascorbyl radical itself technically a prooxidant is not overly potent due to the position of the free radical group, serum half-life vitamin and mineral supplements. It has been noted  that prooxidative effects appear to predominate in vitro at low concentrations of vitamin C relative to minerals usually ironserum half-life vitamin and mineral supplements, and antioxidative effects at higher concentrations of vitamin C relative to minerals.
Exercise is known to reduce oxidation levels in serum   possibly associated with an increase in antioxidant enzymes,   which is said to be an adaptation to the initial increase in oxidative damage induced by exercise.
Vitamin C supplementation has been reported to increase activity of these antioxidant enzymes when acting as a prooxidant. In a study where 11 healthy men took mg of vitamin C twice daily plus IU vitamin E for 4 weeks before being subject to strenuous aerobic exercise, the vitamin group had lower superoxide dismutase activity in their muscles versus the placebo group measured through a muscle biopsy.
However, markers of oxidative stress in the muscle biopsy was ultimately unaffected. A deficiency of vitamin C in rodents tends to result in elevated plasma cortisol without influencing ACTH concentrations, serum half-life vitamin and mineral supplements,   and ACTH stimulation appears to be somewhat hindered despite higher serum cortisol concentrations.
In rats unable to synthesize vitamin C, injections mg per rat are able to delay the turnover of cortisol and enhance its actions in the body  and has been found to enhance ACTH-induced cortisol production.
Supplementation of Vitamin C has been shown to reduce exercise-induced spikes in cortisol after both acute   and up to 12 days supplementation  in the dosage range of 1,mg.