In Vltamin cohort of 21, adults followed for 12 years in the EPIC-Norfolk study, Game fuel replenisher Vitamin C immune support vitamin Vitamin C immune support was imune to be imjune associated with a reduced risk of diabetes Vitain meta-analysis of 29 suppoft randomized controlled trials of short durations median duration, 8 weeks in 1, participants 10 to subjects per trial; including both normotensive and hypertensive subjects found that daily supplementation with 60 to 4, mg of vitamin C median dose, mg reduced systolic blood pressure by 3. Ethanol-induced cardiomyocyte toxicity implicit autophagy and NFkB transcription factor. Vitamin C can improve the absorption of iron that is poorly absorbed, such as iron from meat-free sources.

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Take Vitamin C LIKE THIS For Best Immune Support Deficiencies su;port certain Vitamin C immune support, supporrt vitamin Vitamin C immune support, immuune, and others, ijmune weaken your immune system. Taking supplements of these vitamins may help support Vitamin C immune support system Hormone imbalance remedies. Currently, Vigamin research supports Sustainable energy projects use of any supplement to protect against COVID specifically. Your immune system consists of a complex collection of cells, processes, and chemicals that constantly defends your body against invading pathogens, including viruses, toxins, and bacteria 12. Making healthy lifestyle choices by consuming nutritious foods and getting enough sleep and exercise are the most important ways to bolster your immune system. In addition, research has shown that supplementing with certain vitamins, minerals, herbs, and other substances can help improve immune response and potentially protect against illness.

Vitamin C immune support -

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How well do you score on brain health? Shining light on night blindness. Sautee onions for two minutes. Then add all the spices; toast and stir for two minutes. Add the tomatoes, apples, vinegar and sugar. Mix together and simmer over low heat for 20—30 minutes, stirring occasionally.

Season to taste. Nutrition per serving 2 tablespoons : 24 calories, 0. Kristi Wempen is a dietitian in Nutrition in Mankato , Minnesota. Skip to main content. Posted By. Kristi Wempen, R. Recent Posts. Speaking of Health.

Topics in this Post. Keep the immune system strong While having a healthy immune system is a plus during the season of colds and flu, consider these tips for keeping your immune system strong throughout the year: Focus on a balanced eating plan. Crack down on spreading germs.

Increase sleep, reduce stress. Research demonstrates that lack of sleep and increased stress contribute to illness and overall poor health, so: Adults should get seven to nine hours of sleep each day, while children need eight to 14 hours, depending on age.

Healthy ways to cope with stress include meditating, listening to music or journaling. Physical activity is another strategy to manage stress and may reduce the risk of some chronic diseases that can weaken your immune system.

Here are some myths and facts about immune-boosting nutrients: Fact: Chicken soup can help you feel better. Myth: Vitamin C can prevent illness.

The Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function [VCSIP] study is an ongoing trial designed to confirm these preliminary observations using more accurate measurements of pulmonary function in a larger sample of women randomized to receive supplemental vitamin C or placebo Oxidative stress , neuroinflammation, β- amyloid plaque deposition, Tau protein-forming tangles, and neuronal cell death in the brain of subjects affected by AD have been associated with cognitive decline and memory loss.

Lower vitamin C concentrations in the cerebrospinal fluid CSF and brain extracellular matrix of a mouse model of AD were found to increase oxidative stress and accelerate amyloid deposition and disease progression In another AD mouse model that was lacking the ability to synthesize vitamin C, supplementation with a high versus low dose of vitamin C reduced amyloid deposition in the cortex and hippocampus and limited blood-brain barrier impairments and mitochondrial dysfunction The majority of large, population-based studies examining the relationship of vitamin C intake or supplementation with AD incidence have reported null results In contrast, observational studies reported lower plasma vitamin C concentrations in AD patients compared to cognitively healthy subjects and found better cognitive function or lower risk of cognitive impairment with higher plasma vitamin C Few studies have measured vitamin C concentration in the CSF, which more closely reflects the vitamin C status of the brain.

Vitamin C is concentrated in the brain through a combination of active transport into brain tissue and retention via the blood-brain barrier Although CSF vitamin C is maintained at concentrations several-fold higher than plasma vitamin C, the precise function of vitamin C in cognitive function and AD etiology is not yet fully understood In a small, longitudinal biomarker study in 32 individuals with probable AD, a higher CSF-to-plasma vitamin C ratio at baseline was associated with a slower rate of cognitive decline at one year of follow-up The significance of the CSF-to-plasma vitamin C ratio in AD progression requires further study.

The effect of vitamin C supplementation, in combination with other antioxidants , on CSF biomarkers and cognitive function has been examined in only a few trials involving AD patients.

In this latter trial, a greater decline in the Mini Mental State Examination MMSE score was observed in the supplemented group, however, the significance of this observation remains unclear.

At this time, avoidance of vitamin C deficiency or insufficiency, rather than supplementation in replete individuals, seems prudent for the promotion of healthy brain aging The lens of the eye focuses light, producing a clear, sharp image on the retina , a layer of tissue on the inside back wall of the eyeball.

Age-related changes to the lens thickening, loss of flexibility and oxidative damage contribute to the formation of cataract , i. In humans, vitamin C concentration is about 15 to 20 times higher in the aqueous humor — fluid that fills the anterior and posterior chambers of the eye — than in plasma , suggesting that the vitamin may be playing an important role in the eye Decreased vitamin C concentrations in the lens of the eye have been associated with increased severity of cataracts A meta-analysis of observational studies found that a reduced risk of age-related cataract with higher dietary vitamin C intakes in case-control studies and with higher circulating vitamin C concentrations in cross-sectional studies.

However, no such associations were found in pooled analyses of prospective cohort studies In fact, two prospective cohort studies in Swedish men and women reported that high-dose single nutrient supplements of vitamin C were associated with an increased risk of cataract, especially in those on corticosteroid therapy.

A review of nine randomized controlled trials found no substantial effect of β-carotene, vitamin C, and vitamin E, administered individually or in combination over 2. Urate crystals may form in joints, resulting in inflammation and pain, as well as in the kidneys and urinary tract, resulting in kidney stones.

The tendency to exhibit elevated blood uric acid concentrations and develop gout is often inherited; however, dietary and lifestyle modification may be helpful in both the prevention and treatment of gout In an observational study that included 1, men, higher intakes of vitamin C were associated with lower serum concentrations of uric acid In a cross-sectional study conducted in 4, African Americans, the odds of having hyperuricemia was associated with dietary intakes high in fructose, low in vitamin C, or with high fructose-to-vitamin C ratios A prospective study that followed a cohort of 46, men for 20 years found that total daily vitamin C intake was inversely associated with incidence of gout, with higher intakes being associated with greater risk reductions The results of this study also indicated that supplemental vitamin C may be helpful in the prevention of gout Such a reduction falls within the range of assay variability and is unlikely to be clinically significant An eight-week, open-label , controlled trial randomized 40 subjects with gout to receive either allopurinol standard-of-care , vitamin C, or both treatments The effect of vitamin C, alone or with allopurinol, decreasing serum uric acid was modest and much less than that of allopurinol alone.

The trial did not examine the effect of vitamin C on other outcomes associated with gout Although observational studies suggested that supplemental vitamin C may be helpful to prevent incident and recurrent gout, this has not been demonstrated by intervention studies undertaken thus far.

In addition, there is currently little evidence to support a role for vitamin C in the management of patients with gout Two large prospective cohort studies assessed the relationship between dietary and supplemental vitamin C intakes and mortality. In the Vitamins and Lifestyle Study, 77, men and women ages years were questioned at baseline on their use of dietary supplements during the previous 10 years After five years of follow-up, vitamin C supplement use was associated with a small decreased risk of total mortality, although no association was found with cardiovascular disease - or cancer -specific mortality.

In the second prospective cohort study, the Diet, Cancer and Health Study, 55, Danish adults ages years were questioned at baseline about their lifestyle, diet, and supplement use during the previous 12 months No association between dietary or supplemental intake of vitamin C and mortality was found after approximately 14 years of follow-up.

In contrast, a meta-analysis of 10 prospective cohort studies in 17, women with breast cancer found a lower risk of total and breast cancer-specific mortality with higher supplemental and dietary vitamin C intakes A meta-analysis of 29 trials found no effect of oral vitamin C, given alone or in combination with other antioxidants, on all-cause mortality In parallel to these dietary assessment studies, a strong inverse association between plasma vitamin C and mortality from all-causes, cardiovascular disease, and ischemic heart disease and cancer in men only was observed in the EPIC-Norfolk multicenter, prospective cohort study Similarly, higher serum vitamin C concentrations were associated with decreased risks of cancer-specific and all-cause mortality in 16, adults from the US National Health and Nutrition Examination Survey NHANES III Periprocedural myocardial injury: Coronary angioplasty also called percutaneous transluminal coronary angioplasty is a nonsurgical procedure for treating obstructive coronary heart disease CHD , including unstable angina pectoris , acute myocardial infarction , and multivessel CHD.

Angioplasty involves temporarily inserting and inflating a tiny balloon into the clogged artery to help restore the blood flow to the heart. Periprocedural myocardial injury that occurs in up to one-third of patients undergoing otherwise uncomplicated angioplasty increases the risk of morbidity and mortality at follow-up.

One randomized , placebo -controlled trial has examined the effect of intravenous vitamin C administered to patients with stable angina undergoing elective coronary angioplasty Administration of a 1-gram g vitamin C infusion one hour prior to the angioplasty reduced the concentrations of oxidative stress markers and improved microcirculatory perfusion compared to placebo Another trial randomized patients to receive a 3-g vitamin C infusion or a placebo saline solution within six hours prior to coronary angioplasty Vitamin C treatment substantially reduced the incidence of periprocedural myocardial injury, as assessed by a reduction in the concentrations of two markers of myocardial injury, namely creatine kinase and troponin-I A recent randomized controlled trial assessed the effect of vitamin C and vitamin E administration on reperfusion damage in patients who experienced acute myocardial infarction and underwent coronary angioplasty see below Myocardial reperfusion injury: Reperfusion injury refers to tissue damage occurring at the time of blood flow restoration reperfusion following transient ischemia.

The heart muscle may become oxygen-deprived ischemic as the result of myocardial infarction or with aortic clamping during coronary artery bypass graft CABG surgery. Increased generation of reactive oxygen species ROS when the heart muscle's oxygen supply is restored might be an important contributor to myocardial damage occurring at reperfusion Myocardial reperfusion injury leads to complications, such as reperfusion arrhythmias see Atrial fibrillation and myocardial stunning.

Two randomized controlled trials conducted in the s reported a reduction in reperfusion-induced oxidative stress and myocardial injury with intravenous or oral vitamin C administration prior to CABG surgery reviewed in A more recent randomized, double-blind , placebo -controlled trial has been designed to examine the effect of vitamin C and vitamin E administration on ischemia-reperfusion damage in 99 patients with acute myocardial infarction undergoing coronary angioplasty Vitamin C infusion sodium ascorbate: 3.

The protocol also limited microvascular dysfunction i. However, no difference in the infarct size between antioxidant vitamin treatment and placebo was seen Atrial fibrillation: Atrial fibrillation is the most common type of cardiac arrhythmia. It is also a common post-cardiac surgery complication, leading to an increased risk of cardiovascular morbidity e.

Three meta-analyses of prospective cohort studies and randomized controlled trials have reported an overall reduction in the risk of post-operative atrial fibrillation following administration of primarily oral vitamin C Although only a minority of trials delivered vitamin C intravenously , this administration route appeared to be more effective at reducing the risk of atrial fibrillation — presumably due to higher plasma concentrations achieved Of note, a subgroup analysis in one of the meta-analyses showed a reduction of post-operative atrial fibrillation with vitamin C in non US-based trials 10 trials but no effect of vitamin C in US-based trials 5 trials Cardiovascular disease CVD is the leading cause of death in individuals with diabetes mellitus.

The role of increased oxidative stress in the occurrence of vascular complications in subjects with diabetes has led to hypothesis that higher intakes of antioxidant nutrients could help lower the risk of CVD in diabetic subjects A meta-analysis of randomized controlled trials investigating the effect of antioxidant vitamin supplementation in patients with type 2 diabetes found that most improvement in markers of oxidative stress and blood glucose control could be attributed to vitamin E Another meta-analysis of trials found no effect of vitamins E and C, alone or in combination, on measures of β-cell function and insulin resistance Yet, most studies were small and of short duration and thus did not assess the consequence of long-term use of antioxidant vitamins on the risk of vascular complications in diabetic patients.

Both vitamin C and aspirin reduced fasting blood glucose and HbA1c concentrations and improved blood lipid profile in metformin-treated patients. Compared to placebo, both treatments were found to be more likely to limit risk factors contributing to diabetes-related complications, as well as to lower the risk of future cardiovascular events over a year period estimated using the Framingham risk score Of note, it is possible that genetic differences among diabetic patients influence the effect of vitamin C supplementation on cardiovascular risk.

In particular, a specific allele of the haptoglobin gene Hp , namely Hp2, appears to be associated with an increased risk of diabetic vascular complications. Carriers of two copies of the Hp2 allele Hp express a Hp protein that has a lower capacity to bind and remove pro-oxidant , free hemoglobin Hb from plasma , compared to Hp proteins coded by the Hp and Hp genotypes.

Results from another study by the same investigators suggested that vitamin C could not prevent the oxidation of high-density lipoprotein HDL - cholesterol by glycated Hb-Hp complexes in vitro nor restore impaired HDL function in diabetic mice carrying the Hp genotype Sepsis and septic shock — defined as persistent sepsis-induced low blood pressure — are associated with elevated mortality rates in critically ill patients , Because systemic inflammatory responses involve excessive oxidative stress , it has been suggested that providing antioxidant nutrients like vitamin C may improve the outcome of critically ill patients in intensive care units.

Vitamin C requirements are likely to be increased in this population due to the hypermetabolic response driven by the systemic inflammatory reaction , Intravenous administration of 50 mg or mg of vitamin C per kg per day for 96 hours to patients with sepsis admitted in intensive care unit was found to correct vitamin C deficiency.

Vitamin C also prevented the rise of Sequential Organ Failure Assessment SOFA and Acute Physiologic Assessment and Chronic Health Evaluation APACHE II scores — used to assess severity of illness and risk of mortality — observed in placebo -treated patients Vitamin C infusion also lowered the concentration of markers of inflammation and endothelial injury in patients compared to placebo In another randomized , double-blind , controlled trial in 28 critically ill patients with septic shock, infusion of 25 mg of vitamin C per kg every six hours for 72 hours significantly limited the requirement to vasopressor norepinephrine — decreasing both the dose and duration of treatment — and dramatically improved the day survival rate Similar results have been reported in septic patients given intravenous vitamin C 1.

Compared to standard-of-care, this intervention cocktail more than halved the mean duration of vasopressor use Although intravenous vitamin C administration appears to be safe and well tolerated, there is a non-negligible risk of oxalate nephropathy a rare cause of kidney failure in these critically ill patients Controversy surrounding the efficacy of vitamin C in cancer treatment ensued, leading to the recognition that the route of vitamin C administration is critical 22 , Compared to orally administered vitamin C, intravenous vitamin C can result in 30 to fold higher plasma vitamin C concentrations Higher plasma concentrations achieved via intravenous vitamin C administration are comparable to those that are toxic to cancer cells in culture.

The anticancer mechanism of intravenous vitamin C action is under investigation. It may involve the production of high levels of hydrogen peroxide, selectively toxic to cancer cells 22 , , or the deactivation of hypoxia inducible factor, a prosurvival transcription factor that protects cancer cells from various forms of stress , , Vitamin C likely also plays a role in the maintenance of genome integrity and in the protection against cellular transformation through regulating DNA and histone demethylating enzymes see Function Current evidence from controlled clinical trials indicates that intravenous vitamin C is generally safe and well tolerated in cancer patients.

Of note, because intravenous administration of 80 g of vitamin C precipitated hemolytic anemia in two subjects with glucosephosphate dehydrogenase deficiency, patients due to receive high-dose vitamin C infusion are systematically screened for this genetic disorder Four phase I clinical trials in patients with advanced cancer found that intravenous administration of vitamin C at doses up to 1.

A phase I study in nine patients with metastatic pancreatic cancer showed that millimolar concentrations of plasma vitamin C could be reached safely when administered in conjunction with the cancer chemotherapy drugs, gemcitabine and erlotinib Retrospective in vitro colony formation assays revealed that patient leukemic cells displayed variable sensitivity to vitamin C treatment: leukemic cells from seven out of the nine patients who experienced a significant clinical benefit were sensitive to vitamin C in vitro i.

Thus, in vitro vitamin C sensitivity assays may provide predictive value for the clinical response to intravenous vitamin C treatment. The mechanisms underlying differential sensitivity to vitamin C are under investigation.

In vitro experiments performed using 11 different cancer cell lines demonstrated that sensitivity to vitamin C correlated with the expression of catalase, an enzyme involved in the decomposition of hydrogen peroxide Approximately one-half of the cell lines tested were resistant to vitamin C cytotoxicity, a response associated with high levels of catalase activity.

Sensitivity to vitamin C may also be determined by the expression of sodium-dependent vitamin C transporter-2 SVCT-2 , which transports vitamin C into cells Higher SVCT-2 levels were associated with enhanced sensitivity to vitamin C in nine different breast cancer cell lines.

Moreover, SVCT-2 was significantly expressed in 20 breast cancer tissue samples, but weakly expressed in normal tissues.

Finally, mutations in genes coding for vitamin C-dependent TET demethylases, mutations that are common in cancer cells, may also contribute to resistance to vitamin C treatment Current evidence of the efficacy of intravenous vitamin C in cancer patients is limited to observational studies , uncontrolled interventions , and case reports , There is a need for larger, longer-duration phase II clinical trials that test the efficacy of intravenous vitamin C in disease progression and overall survival In the past 40 years, numerous placebo -controlled trials have examined the effect of vitamin C supplementation on the prevention and treatment of colds.

A meta-analysis of 53 placebo-controlled trials evaluated the effect of vitamin C supplementation on the incidence, duration, or severity of the common cold when taken as a continuous daily supplement 43 trials or as therapy upon onset of cold symptoms 10 trials Regarding the incidence of colds, a difference was observed between two groups of participants.

Regular supplementation with vitamin C 0. In addition, a systematic review by the same investigators identified only two small randomized , double-blind , placebo-controlled trials that examined the effect of vitamin C on the incidence of respiratory infection-induced asthma These observations need to be confirmed in larger, well-designed trials.

A systematic review identified 11 randomized controlled studies that evaluated the effect of vitamin C on asthma eight trials or exercise-induced bronchoconstriction three trials In the three trials that included a total of 40 participants with exercise-induced bronchoconstriction, vitamin C administration before exercise a 0.

Among the five out of eight trials in asthmatic subjects that reported on FEV 1 outcomes, none found a difference between vitamin C supplementation and placebo Although the use of lead paint and leaded gasoline has been discontinued in the US, lead toxicity continues to be a significant health problem, especially in children living in urban areas.

Abnormal growth and development have been observed in infants of women exposed to lead during pregnancy, while children who are chronically exposed to lead are more likely to develop learning disabilities, behavioral problems, and to have a low IQ. In adults, lead toxicity may result in kidney damage, high blood pressure, and anemia.

Several cross-sectional studies have reported an inverse association between vitamin C status and blood lead concentration. A much larger study of 19, people, including 4, children from 6 to 16 years of age, found higher serum vitamin C concentrations to be associated with significantly lower blood lead concentrations A US national survey of more than 10, adults found that blood lead concentrations were inversely related to serum vitamin C concentrations Cigarette smoking or second-hand exposure to cigarette smoke contributes to increased blood lead concentration and a state of chronic low-level lead exposure.

The mechanism s by which vitamin C reduces blood lead concentration is not known, yet it has been proposed that vitamin C could inhibit intestinal absorption or enhance urinary excretion of lead Unlike plants and most animals, humans have lost the ability to synthesize vitamin C endogenously and therefore have an essential dietary requirement for this vitamin see The Recommended Dietary Allowance.

Results from 7, participants in the US National Health and Nutrition Examination Survey NHANES indicated that an estimated 7.

The national study identified smokers and those of lower socioeconomic status to both be at higher risk for vitamin C deficiency As shown in Table 3 , different fruit and vegetables vary in their vitamin C content, but five servings 2½ cup-equivalents of a variety of fruit and vegetables should average out to about to mg of vitamin C, especially if vitamin C-rich fruits are consumed.

If you wish to check foods for their vitamin C content, search USDA's FoodData Central. Vitamin C L-ascorbic acid is available in many forms, but there is little scientific evidence that any one form is better absorbed or more effective than another.

Most experimental and clinical research uses ascorbic acid or its sodium salt, called sodium ascorbate. Natural and synthetic L-ascorbic acid are chemically identical and there are no known differences regarding biological activities or bioavailability Mineral salts of vitamin C are considered less acidic than vitamin C and therefore are considered "buffered.

Sodium ascorbate and calcium ascorbate are the most common forms, although a number of other mineral ascorbates are available.

Sodium ascorbate provides mg of sodium mg of ascorbic acid per 1, mg of sodium ascorbate, and calcium ascorbate generally provides 90 to mg of calcium mg of ascorbic acid per 1, mg of calcium ascorbate.

Flavonoids are a class of water-soluble plant pigments that are often found in vitamin C-rich fruit and vegetables, especially citrus fruit and berries see the article on Flavonoids.

There is little evidence that the flavonoids in most commercial preparations increase the bioavailability or efficacy of vitamin C Some, yet not all, studies in animal models such as vitamin C-deficient guinea pigs or genetically scorbutic rats found an increased uptake of vitamin C in peripheral circulation and specific organs in the presence of flavonoids.

However, studies conducted in humans found no differences in bioavailability of vitamin C from flavonoid-rich whole fruit or fruit juice and synthetic vitamin C reviewed in One supplement, Ester-C ® , contains mainly calcium ascorbate and includes small amounts of the vitamin C metabolites , dehydroascorbic acid oxidized ascorbic acid , calcium threonate, and trace amounts of xylonate and lyxonate.

Although these metabolites are purported to increase the bioavailability of vitamin C, the only published study in humans addressing this issue found no difference between Ester-C ® and commercially available vitamin C tablets with respect to the absorption and urinary excretion of vitamin C Ester-C ® should not be confused with ascorbyl palmitate, which is also marketed as "vitamin C ester" see below.

Ascorbyl palmitate is a vitamin C ester i. In this case, vitamin C is esterified to the saturated fatty acid , palmitic acid, resulting in a fat-soluble form of vitamin C. Ascorbyl palmitate has been added to a number of skin creams due to interest in its antioxidant properties, as well as its importance in collagen synthesis see the separate article, Vitamin C and Skin Health Although ascorbyl palmitate is also available as an oral supplement, most of it is likely hydrolyzed to ascorbic acid and palmitic acid in the digestive tract before it is absorbed Ascorbyl palmitate is marketed as "vitamin C ester," which should not be confused with Ester-C ® see above.

One small placebo -controlled, cross-over trial in 11 men showed that the oral administration of 4 g of vitamin C resulted in a greater vitamin C concentration in plasma over a four-hour period when vitamin C was encapsulated in liposomes compared to unencapsulated vitamin C Although liposomal encapsulation could increase vitamin C bioavailability , plasma vitamin C concentrations were much lower than those achieved with intravenous vitamin C administration For a more detailed review of scientific research on the bioavailability of different forms of vitamin C, see The Bioavailability of Different Forms of Vitamin C.

A number of possible adverse health effects of very large doses of vitamin C have been identified, mainly based on in vitro experiments or isolated case reports , and include genetic mutations , birth defects, cancer, atherosclerosis, kidney stones , "rebound scurvy ," increased oxidative stress , excess iron absorption, vitamin B 12 deficiency, and erosion of dental enamel.

The concern of kidney stone formation with vitamin C supplementation is discussed below. With the latest RDA published in , a tolerable upper intake level UL for vitamin C was set for the first time Table 4.

A UL of 2 g 2, mg daily was recommended in order to prevent generally healthy adults from experiencing diarrhea and gastrointestinal disturbances Such symptoms are not generally serious, especially if they resolve with temporary discontinuation of vitamin C supplementation.

Because oxalate is a metabolite of vitamin C, there is some concern that high vitamin C intake could increase the risk of calcium oxalate kidney stones.

Some 24 , , , but not all , studies have reported that supplemental vitamin C increases urinary oxalate concentrations. Whether any increase in oxalate levels would translate to an elevation in risk for kidney stones has been examined in several epidemiological studies.

On the other hand, two other large prospective studies reported that a high intake of vitamin C was associated with an increased risk of kidney stone formation in men , Specifically, the Health Professionals Follow-Up Study collected data on dietary and supplemental vitamin C intake every four years in 45, male health professionals ages years In the Cohort of Swedish Men study, self-reported use of single-nutrient vitamin C supplements taken seven or more times per week at baseline was associated with a two-fold higher risk of incident kidney stones among 48, men ages years followed for 11 years Despite conflicting results, it may be prudent for individuals predisposed to oxalate kidney stone formation to avoid high-dose vitamin C supplementation.

Overall, evidence suggesting specific drugs can lower blood vitamin C concentrations in humans is limited. Dihydropyridine calcium channel blockers e.

However, a reduction in blood vitamin C concentrations with these drugs has not been reported in humans Aspirin can impair vitamin C status if taken frequently Conversely, there are case reports suggesting that supplemental vitamin C may lower blood concentrations of some medications, such as fluphenazine the antipsychotic drug, Prolixin and indinavir the antiretroviral drug, Crixivan There is some evidence, though controversial, that vitamin C interacts with anticoagulant medications like warfarin Coumadin.

Large doses of vitamin C may block the action of warfarin and thus lower its effectiveness. In addition, vitamin C may bind aluminum in the gut and increase the absorption of aluminum-containing compounds e.

People with impaired kidney function may be at risk for aluminum toxicity when supplemental vitamin C is taken at the same time as these compounds , Finally, supplemental vitamin C may increase blood estrogen concentrations in women using oral contraceptives or hormone replacement therapy The potential effect of antioxidants during chemotherapy is not well understood, yet only likely to be an issue if a specific chemotherapeutic agent acts through an oxidative mechanism, which is uncommon It is not clear whether vitamin C given parenterally could diminish or increase the efficacy of chemotherapy drugs — in particular, akylating agents e.

Patients are advised to discuss with their oncologist before using vitamin C supplements , Because high doses of vitamin C have also been found to interfere with the interpretation of certain laboratory tests e.

A three-year randomized controlled trial in patients with documented coronary heart disease and low blood HDL concentrations found that a combination of simvastatin Zocor and niacin increased HDL concentration, inhibited the progression of coronary artery stenosis narrowing , and decreased the frequency of cardiovascular events, such as myocardial infarction and stroke Surprisingly, when an antioxidant combination 1, mg vitamin C, IU vitamin E, µg selenium, and 25 mg β-carotene daily was taken with the simvastatin-niacin combination, the protective effects were diminished.

Since the antioxidants were taken together in this trial, the individual contribution of vitamin C cannot be determined. In contrast, a much larger trial in more than 20, men and women with coronary heart disease or diabetes mellitus found that simvastatin and an antioxidant combination mg vitamin E, mg vitamin C, and 20 mg β-carotene daily did not diminish the cardioprotective effects of simvastatin therapy over a five-year period These contradictory findings indicate that further research is needed on potential interactions between antioxidant supplements and cholesterol -lowering drugs, such as HMG-CoA reductase inhibitors statins.

Vitamin C is known to function as a highly effective antioxidant in living organisms. However, in test tube experiments, vitamin C can interact with some free metal ions and lead to the generation of potentially damaging free radicals.

Although free metal ions are not generally found under physiological conditions, the idea that high doses of vitamin C might be able to promote oxidative damage in vivo has received a great deal of attention. Widespread publicity has been given to a few studies suggesting a pro-oxidant effect of vitamin C , , but these studies turned out to be either flawed or of no physiological relevance.

A comprehensive review of the literature found no credible scientific evidence that supplemental vitamin C promotes oxidative damage under physiological conditions or in humans Thus, the Linus Pauling Institute recommends a vitamin C intake of mg daily for adults to ensure replete tissue concentrations 29 — an amount substantially higher than the RDA yet with minimal risk of side effects.

This recommendation can be met through food if the diet includes at least several servings of vitamin C-rich fruit and vegetables e. Most multivitamin supplements provide at least 60 mg of vitamin C. A vitamin C intake of at least mg daily may be particularly important for older adults who are at higher risk for age-related chronic diseases.

Pharmacokinetic studies in older adults have not yet been conducted, but there is some evidence suggesting that the efficiency of one of the molecular mechanisms for the cellular uptake of vitamin C declines with age Because maximizing blood concentrations of vitamin C may be important in protecting against oxidative damage to cells and biological molecules, a vitamin C intake of at least mg daily might benefit older adults who are at higher risk for chronic diseases caused, in part, by oxidative damage, such as heart disease, stroke , certain cancers , and cataract.

For more information on the difference between Dr Linus Pauling's recommendation and the Linus Pauling Institute's recommendation for vitamin C intake , select the highlighted text. Originally written in by: Jane Higdon, Ph.

Linus Pauling Institute Oregon State University. Updated in November by: Jane Higdon, Ph. Updated in September by: Jane Higdon, Ph. Updated in December by: Jane Higdon, Ph. Updated in January by: Jane Higdon, Ph. Updated in September by: Victoria J. Drake, Ph. Updated in November by: Giana Angelo, Ph.

Updated in July by: Barbara Delage, Ph. Reviewed in December by: Anitra C. Carr, Ph. Reviewed in December by: Alexander J. Michels, Ph. Research Associate Linus Pauling Institute Oregon State University.

Levine M, Padayatty SJ. Vitamin C. In: Ross AC, Caballero B, Cousins RJ, Tucker KL, Ziegler TR, eds. Modern Nutrition in Health and Disease, 11 th ed.

Englard S, Seifter S. The biochemical functions of ascorbic acid. Annu Rev Nutr. The epigenetic role of vitamin C in health and disease. Cell Mol Life Sci. Regulation of the epigenome by vitamin C. Antiviral and immunomodulatory activities of ascorbic acid.

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Relationships between ascorbic acid and serum proteins of the immune system. Br Med J. Anderson R, Oosthuizen R, Maritz R, Theron A, Van Rensburg AJ. The effects of increasing weekly doses of ascorbate on certain cellular and humoral immune functions in normal volunteers.

Am J Clin Nutr. Levy R, Shriker O, Porath A, Riesenberg K, Schlaeffer F. Vitamin C for the treatment of recurrent furunculosis in patients with impaired neutrophil functions. J Infect Dis. Bergsten P, Amitai G, Kehrl J, Dhariwal KR, Klein HG, Levine M. Millimolar concentrations of ascorbic acid in purified human mononuclear leukocytes.

Depletion and reaccumulation. J Biol Chem. Evans RM, Currie L, Campbell A. The distribution of ascorbic acid between various cellular components of blood, in normal individuals, and its relation to the plasma concentration. Br J Nutr. Jariwalla RJ, Harakeh S. Mechanisms underlying the action of vitamin C in viral and immunodeficiency disease.

In: Packer L, Fuchs J, eds. Vitamin C in Health and Disease. New York: Macel Dekker, Inc. Alberts B, Bray D, Lewis J, Raff M. Differentiated cells and the maintenance of tissues. Molecular Biology of the Cell. New York: Garland Publishing, Inc. Pauling L.

The immune system. How to Live Longer and Feel Better. Corvallis: Oregon State University Press; Dahl H, Degre M. The effect of ascorbic acid on production of human interferon and the antiviral activity in vitro. Acta Pathol Microbiol Scand B. Carr AC, Maggini S.

Vitamin C and immune function. Lykkesfeldt J, Poulsen HE. Is vitamin C supplementation beneficial? Lessons learned from randomised controlled trials. Michels AJ, Frei B. Myths, artifacts, and fatal flaws: identifying limitations and opportunities in vitamin C research. Johnston CS. In: Erdman JWJ, Macdonald IA, Zeisel SH, eds.

Present Knowledge in Nutrition. Ames, Iowa: Wiley-Blackwell; Levine M, Padayatty SJ, Espey MG. Vitamin C: a concentration-function approach yields pharmacology and therapeutic discoveries. Adv Nutr. Levine M, Wang Y, Padayatty SJ, Morrow J.

A new recommended dietary allowance of vitamin C for healthy young women. Proc Natl Acad Sci U S A. Levine M, Conry-Cantilena C, Wang Y, et al. Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance.

Padayatty SJ, Sun H, Wang Y, et al. Vitamin C pharmacokinetics: implications for oral and intravenous use. Ann Intern Med. Carr AC, Bozonet SM, Pullar JM, Simcock JW, Vissers MC.

Human skeletal muscle ascorbate is highly responsive to changes in vitamin C intake and plasma concentrations. Michels AJ, Hagen TM, Frei B.

Human genetic variation influences vitamin C homeostasis by altering vitamin C transport and antioxidant enzyme function. Carr AC, Pullar JM, Bozonet SM, Vissers MC. Marginal ascorbate status hypovitaminosis C results in an attenuated response to vitamin C supplementation. Frei B, Birlouez-Aragon I, Lykkesfeldt J.

Authors' perspective: What is the optimum intake of vitamin C in humans? Crit Rev Food Sci Nutr. Levine M, Rumsey SC, Daruwala R, Park JB, Wang Y. Criteria and recommendations for vitamin C intake.

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