Vitamin C (also known as ascorbic acid) is a powerful antioxidant abundant in vegetables and fruits. Vitamin C helps to repair and regenerate tissues, protect against heart disease, improve respiratory function, aid in the absorption of iron, and prevent scurvy. Research indicates that vitamin C may help protect against a variety of cancers. Supplemental vitamin C may also lessen the duration and symptoms of a common cold, help delay or prevent some eye diseases, and support healthy immune function. Vitamin C is easy to obtain from intake of foods because many fruits (especially citrus) and vegetables contain vitamin C. However, vitamin C dietary supplements might reduce the heart-protective effects of statins which are taken to control blood-cholesterol levels. Additionally they may interact with the effectiveness of antiretrovirals.
Vitamin C and lung function in adults:
Vitamin C, respiratory symptoms, and lung function: A vitamin C protective effect against the development of respiratory symptoms was observed in a study of 2,526 adults between 1971 and 1972. This study evaluated vitamin C intake and lung (pulmonary) function using forced expiratory volume in 1 second (FEV1), an important measure performance of lung function by amount of air movement within 1 second. After adjusting for variables, dietary vitamin C intake from vegetables was positively and significantly associated with a higher FEV1. Those consuming an average of vitamin C of 17 mg/day, 66 mg/day, or 128 mg/day had average FEV1 values of about 2530 ml, 2550 ml, 2570 ml, respectively. The authors concluded that vitamin C had a protective effect on lung function. This beneficial effect was not restricted to just smokers. Vitamin C intake also appeared to benefit patients with asthma and bronchitis. (1)
Britton and colleague studied the association between vitamin C and E on lung function in a study involving 2,633 subjects aged 17-70 years old. The authors found that a higher intake of vitamin C was associated with a higher forced expiratory volume in 1 second (FEV1), an important measure performance of lung function measuring amount of air movement within 1 second and a higher forced vital capacity (FVC), a measure of the strength of lung muscles by measuring the maximum amount of air a person can expel from the lungs. An increase in vitamin C of 40mg/d was associated with a significant increase in FEV1 and FVC of 25.0 ml and 23.3 ml, respectively. An increase in vitamin E of 2.2mg was also associated with increase in FEVI and FVC of 20.1 ml and 23.1 ml. However, the authors conclude that much of the beneficial effect was due to vitamin C. (2)
Vitamin C and lung function in children:
In a cross-sectional study of 2,650 children aged 8-11 years old in the UK, Cook and colleagues reported that forced expiratory volume in 1 second (FEV1), a measure of lung function, was positively linked with the frequency of fresh fruits, green vegetables, and salad consumption but was not associated with blood vitamin C levels. The beneficial effect was strongest from fruit consumption. Compared to children who never ate fresh fruit, those who ate fresh fruit more than once a day had a 79 ml or 4.3% higher FEV1 value. This link between FEV1 and fruit intake was stronger in children with wheeze than those without. (3)
Vitamin C and fruit intake in children:
In children aged 6–7 years, those who ate at least 5 serving of fruit rich in vitamin C per week were less likely to have respiratory-related health problems including wheezing, shortness of breath, or night coughing compared with those who never ate fruit. This study, which followed 18,737 children living in Central and Northern Italy, found that those eating the most citrus and kiwifruit (5-7 servings per week) had 44% less incidence of wheezing compared to children eating the least (less than once a week). Shortness of breath was reduced by 32%, severe wheeze by 41%, night time cough by 27%, chronic cough by 25%, and runny nose by 28%. Children who had asthma when the study began appeared to benefit the most, and protective effects were evident even among children who ate fruit only once or twice a week. (4)
Vitamin C and colon adenomas:
Antioxidant vitamins A, C, and E were found to lower the recurrence rate of cancers of the colon. Individuals (n=255) with a history of colonic adenoma were randomized to receive treatment with either (1) vitamin A (30,000 IU per day), vitamin C (1 gram per day), and vitamin E (70 mg per day); (2) lactulose; or (3) placebo for an average of 18 months. At the end of the treatment period, adenoma recurrence had occurred in 5.7% of the antioxidant vitamin group compared to 14.7% in the lactulose group and 35.9% in the placebo group. (5)
Vitamin C and cancer mortality:
Intravenous vitamin C and cancer mortality:
Researchers investigated health-related quality of life after intravenous (IV) administration of high-dose vitamin C in 39 patients dying from cancer. All patients received 10 g vitamin C intravenously with a 3-day interval combined with a daily oral intake of 4 g for a week. After administration of vitamin C, overall health scores measuring using a questionnaire developed to assess the quality of life of cancer patients (EORTC QLQ-C30) improved from 36 to 55. Patients reported significantly higher scores for physical, role, emotional, and cognitive function. Significantly lower scores for fatigue, nausea/vomiting, pain, and appetite loss were also reported. High-dose vitamin C IV injections has been found to increase the quality of life in patients dying from cancer. After 1 wk of vitamin C therapy 39 terminal cancer patients experience improved emotional and cognitive function. Additionally, a reduction in pain and fatigued were reported. (8)
Three people with advanced cancer were found to have increased survival times after receiving intravenously administered high-dose vitamin C. Double blind placebo controlled trials conducted on oral vitamin C therapy was found to show no benefit in cancer patients. Oral vitamin C given at the maximum recommended dose of 18g/d led to a blood concentration of only 220 micromol/L. In comparison, at the same dose, intravenous administration of vitamin C led to a 25-fold increase in blood concentration. Intravenous doses of 50-100g vitamin C result in a blood concentration around 14,000 micromol/L. In laboratory studies, a blood concentration of 1,000 micromol/L vitamin C damages cancer cells, but does not harm healthy cells. New research should be pursued in IV vitamin C for cancer treatment. (6)
Vitamin C intake and cancer mortality in men:
Loria CM and Klag MJ et al found an association between low blood ascorbate (vitamin C) levels and an increased risk of mortality overall and from cancer, among men. Compared to men with high ascorbate blood concentrations (73.8 micromol/L or greater), men with low ascorbate blood concentrations (less than 28.4 micromol/L) have a 57% increased total mortality risk and a 62% increased mortality risk from cancer. No change in risk of mortality was found among men with ascorbate blood concentrations between 28.4 to 73.8 micromol/L. The vitamin C intake corresponding to the higher risk of mortality in men was less than or equal to 60 mg per day. No link between mortality and ascorbate levels were found among women. (7)
Vitamin C intake and cancer mortality:
Carr and Frei recommended a higher vitamin C intake of 90-100 mg per day to avoid chronic diseases and showed somewhat different findings after reviewing cohort studies. They found that low intake of vitamin C was related to an increase in cancer mortality. They also had a different conclusion than Loria et al in that intake of vitamin C was inversely related to cancer mortality in elderly women but not mortality in men. (21)
Vitamin C and heart disease:
Carr and Frei recommended a higher vitamin C intake of 90-100 mg per day to avoid chronic diseases. They found prospective studies which demonstrated that a low vitamin C poses a higher risk of cardiovascular disease. (21)
Vitamin C deficiency:
Minimum required vitamin C intake: An average vitamin C intake of 46 mg per day is required to prevent scurvy (21), a deficiency state of vitamin C resulting in weakness, anemia, bruising of the skin and gum disease.
Peri-follicular petechiae: A man (59 years old) presented with a case of peri-follicular petechiae of the extremities caused by a vitamin C deficiency. Peri-follicular petechiae, a common symptom of scurvy (caused by vitamin C deficiency) are cause by small hemorrhages (broken capillary blood vessels) on the skin. After increasing intake of vitamin C, the patient’s symptoms improved dramatically. (10)
Hemodialysis patients and vitamin C: Patients on dialysis are at high risk for vitamin C deficiency. Individuals suffering from chronic kidney disease are recommended to have a daily intake of 60 mg of ascorbate (vitamin C). If a patient is suspected of reduced ascorbate levels, then 1-1.5g of orally administered ascorbate per week should be taken or 300 mg via another route other than the mouth is recommended. (11)
Vitamin C and pre-eclampsia: Low vitamin C levels have reported to be associated with pre-eclampsia. (12)
The relationship of vitamin C and iron deficiency anemia has been investigated. Researchers conducted a systematic review of studies looking at the relationship of vitamin supplementation on anemia. It was found that administration of vitamin C enhances the absorption of dietary iron in the gut. (13,21)
Vitamin C and eye health:
Age-related macular degeneration (AMD) is an aging change in the back of the eye that may lead to loss of the central vision. Antioxidants including vitamin C, 500 mg; vitamin E, 400 IU; beta carotene, 15 mg; and zinc, 80 mg as zinc oxide with 2 mg of cupric oxide) may be beneficial in reducing risk of AMD progression as seen among Age-Related Eye Disease Study (AREDS) participants. (14)
Vitamin C and colds:
When vitamin C was tested for treatment of colds in 7 separate studies that included 3294 cold episodes, vitamin C was no more effective than placebo at shortening the duration of cold symptoms except in one study that found patients taking 8g of vitamin C when cold symptoms started had shorter colds than those taking 4g. A review of 30 prevention trials (N=11,350) revealed that, while severity remained unchanged, when taken daily at 1g, vitamin C very slightly shortened cold duration—by 8% in adults and 18% in children. This means a shorter cold episode by 1.5 to 2 days assuming the typical cold runs 7 to 10 days. Finally, researchers found the most effect in subjects who were in extreme conditions, such as marathon runners. In this group of 642 individuals (6 trials), taking vitamin C at 200 to 2000 mg/d cut their risk of catching a cold in half. (15)
Vitamin C adverse reactions and interactions:
A vitamin C supplement intake of over 2 grams per day is poorly tolerated, may not be safe and results in gastrointestinal side effects. High doses of up to 18 grams per day did not result in significantly higher blood vitamin C levels. (6)
A review of data (8 clinical trials and 1 population trial) on drug interactions found significant interactions between vitamin C and HIV drugs. (16)
Most antiretrovirals (taken by patients with HIV) are metabolized via the CYP3A4 and P-glycoprotein systems. Dietary supplements that effect the metabolism of these systems may decrease anti-retrovirals levels, and thus their effectiveness. Limited clinical research has demonstrated reductions in antiretroviral levels in patients taking vitamin C. (17)
Vitamin C administration guidelines:
Vitamin C has been shown to be beneficial for people with certain diseases or conditions. High intakes of vitamin C have been associated with decreased risk of heart disease, cancer, eye diseases, and neurological conditions. High dose vitamin C, with an upper tolerable level set at 2 grams daily, has been shown to be safe. Among healthy individuals, the recommended daily intake of vitamin C is 75 mg for women and 90 mg for men. (18)
Vitamin C and the USPSTF:
For the prevention of cancer or cardiovascular disease, according to the U.S. Preventive Services Task Force (USPSTF), there is insufficient evidence to recommend for or against the use of vitamins A, C, or E supplements or multivitamins with folic acid or antioxidant combinations for the prevention of cancer or cardiovascular disease. (19)
Common High Vitamin C Containing Foods:
| Asparagus, frozen, cooked, boiled, drained, without salt, 1 cup | 43.9 mg |
| Blackberries, raw, 1 cup | 30.2 mg |
| Broccoli, cooked, boiled, drained, without salt, 1 cup | 101.2 mg |
| Cauliflower, cooked, boiled, drained, without salt, 1 cup | 54.9 mg |
| Cereals ready-to-eat, GENERAL MILLS, Whole Grain TOTAL, 3/4 cup | 60.0 mg |
| Cereals ready-to-eat, KELLOGG’S PRODUCT 19, 1 cup | 61.2 mg |
| Cranberry juice cocktail, bottled, 8 fl oz | 107.0 mg |
| Kiwifruit, green, raw, 1 medium | 70.5 mg |
| Kale, cooked, boiled, drained, without salt, 1 cup | 53.3 mg |
| Mangos, raw, 1 mango | 75.3 mg |
| Melons, cantaloupe, raw, 1 cup | 58.7 mg |
| Orange juice, chilled, includes from concentrate, 1 cup | 83.7 mg |
| Peas, edible-podded, boiled, drained, without salt, 1 cup | 76.6 mg |
| Peppers, sweet, green, raw, 1 pepper | 95.7 mg |
| Pineapple, raw, all varieties, 1 cup | 74.1 mg |
| Snacks, fruit leather, rolls, 1 large | 25.2 mg |
| Spinach, cooked, boiled, drained, without salt, 1 cup | 17.6 mg |
| Strawberries, raw, 1 cup | 97.6 mg |
| Sweet potato, cooked, baked in skin, without salt, 1 potato | 28.6 mg |
| Tomato juice, canned, with salt added, 1 cup | 44.5 mg |
| Vegetable juice cocktail, canned, 1 cup | 67.0 mg |
| Watermelon, raw, 1 wedge | 23.2 mg |
Adapted from: Nutritive Value of Foods, United States Department of Agriculture, Agricultural Research Service, Home and Garden Bulletin Number 72. May be accessed at: https://www.ars.usda.gov/SP2UserFiles/Place/12354500/Data/SR25/nutrlist/sr25w401.pdf
Assessment and Plan: Vitamin C
- High intakes of vitamin C have been associated with lower risk of heart disease, cancer, eye diseases, and neurological conditions. High dose vitamin C, with an upper tolerable level set at 2g, has been shown to be safe. Among healthy individuals, the recommended daily intake of vitamin C is 75 mg for women and 90 mg for men. (18)
- An average vitamin C intake of 46 mg per day is required to prevent scurvy (21), a deficiency state of vitamin C resulting in weakness, anemia, bruising of the skin and gum disease.
- A vitamin C supplement intake of over 2 grams per day is poorly tolerated, may not be safe and results in gastrointestinal side effects. High doses of up to 18 grams per day did not result in significantly higher blood vitamin C levels. (6)
- There is evidence that vitamin C intake has a benefit in lowering mortality risk for men but not in women. Men with low ascorbate blood concentrations compared with higher concentrations showed a 57% higher total mortality risk and a 62% higher cancer mortality risk. No change in risk of mortality was found with levels between 28.4 to 73.8 micromol/L. The vitamin C intake corresponding to the higher risk of mortality in men was less than or equal to 60 mg per day. (7)
- Carr and Frei recommended a higher vitamin C intake of 90-100 mg per day to avoid chronic diseases. These authors expressed similar to findings as Loria, CM et al which were that low intake of vitamin C was related to an increase in cancer mortality. Carr and Frei had a different conclusion than Loria et al in that intake of vitamin C was inversely related to cancer mortality in elderly women but not in men. They also found prospective studies which demonstrated that a low vitamin C poses a higher risk of cardiovascular disease. (21)
- Intravenous vitamin C results in significantly higher blood levels than oral doses, appears to damage cancer cells, but not healthy cells and may provide survival benefit in cancer patients (6). It may also improve physical function, emotional well-being, cognitive ability, and may result in lower rates of fatigue, nausea, vomiting, pain, and anorexia in cancer patients (8).
- Higher intakes of dietary vitamin C from fruits and vegetables was positively and significantly associated with a higher forced expiratory volume in 1 second (FEV1) (1,2,3), an important measure of lung function for patients with asthma and bronchitis patients as well as in smokers, healthy adults and children. The degree of improvement in lung function in the research above is a range between 1-5%.
- It is difficult to separate out whether this improvement in lung function is related to vitamin C itself or related to overall nutrient content contained within the fruit. One study found that the improvement in higher (forced expiratory volume in 1 second) FEV1 was positively linked with the frequency of fresh fruits, green vegetables, and salad consumption but was not associated with vitamin C levels in the blood (3).
- A study which followed over 18,000 children found that those who consumed 5 servings of fruit rich in vitamin C per week were less likely to have respiratory-related health problems including wheezing, shortness of breath, or night coughing compared with those who never ate fruit with the greatest benefit seen in children with asthma. Those eating the most citrus and kiwifruit (5-7 servings per week) had 44% less incidence of wheezing compared to children eating the least (less than once a week). Shortness of breath was reduced by 32%, severe wheeze by 41%, night time cough by 27%, chronic cough by 25%, and runny nose by 28%. (4)
- A supplement containing vitamin A (30,000 IU per day), vitamin C (1 gram per day), and vitamin E (70 mg per day taken for about 18 months showed a significant reduction in colonic adenoma recurrence (5).
- Patients on dialysis and chronic kidney disease are at high risk for vitamin C deficiency and are recommended to have a daily intake of 60 mg of ascorbate (vitamin C). A dose of 1-1.5g of orally administered vitamin C per week is acceptable. (11)
- Vitamin C has been reported to be associated with pre-eclampsia when levels of this vitamin are low (12).
- For patients with iron deficiency anemia, administration of vitamin C is useful to enhance the absorption of dietary iron in the gut (13).
- Vitamin C, 500 mg along with vitamin E, 400 IU; beta carotene, 15 mg; and zinc, 80 mg as zinc oxide with 2 mg of cupric oxide reduced the risk of age-related macular degeneration progression (14).
- A review of 30 prevention trials showed that vitamin C, 1g daily slightly shortened cold duration—by 8% in adults and 18% in children. A review of 6 trials found that vitamin C at 200 to 2000 mg per day was even more effective for subjects in extreme conditions, such as marathon runners, which cut their risk of a contracting a cold by about half. (15)
- Clinical research has demonstrated reductions in antiretroviral levels in patients taking vitamin C. (17)
- To see vitamin C content within foods, please see above or click the link (20): https://www.ars.usda.gov/SP2UserFiles/Place/12354500/Data/SR25/nutrlist/sr25w401.pdf
- Despite many positive findings in vitamin C research, the U.S. Preventive Services Task Force (USPSTF), determined that there is insufficient evidence to recommend for or against the use of vitamin C for the prevention of cancer or cardiovascular disease. (19)
References:
1.Schwartz J, Weiss ST. Relationship between dietary vitaminC intake and pulmonary function in the First National Health and Nutrition Examination Survey (NHANES I). Am J Clin Nutr 1994;59:110-14. http://ajcn.nutrition.org/content/59/1/110.long
2.Britton JR, Pavord ID, Richards A, et al. Dietary antioxidantvitamin intake and lung function in the general population. Am J Respir Crit Care Med 1995;151:1383-7. http://www.ncbi.nlm.nih.gov/pubmed/7735589
3.Cook DG, Carey IM, Whincup PH, et al. Effect of fresh fruit consumption on lung function and wheeze in children. Thorax 1997 Jul;52(7):628-33.http://www.ncbi.nlm.nih.gov/pubmed/9246135
4.Forastiere F, Pistelli R, Sestini P, et al. Consumption of fresh fruit rich in vitamin C and wheezing symptoms in children. SIDRIA Collaborative Group, Italy (Italian Studies on Respiratory Disorders in Children and the Environment). Thorax 2000;55(4):283–288. http://www.ncbi.nlm.nih.gov/pubmed/10722767
5.Roncucci L, Di Donato P, Carati L, et al. Antioxidant vitamins or lactulose for the prevention of the recurrence of colorectal adenomas. Colorectal Cancer Study Group of the University of Modena and the Health Care District 16. Dis Colon Rectum. 1993 Mar;36(3):227-34. http://www.ncbi.nlm.nih.gov/pubmed/8449125
6.Padayatty SJ, Riordan HD, Hewitt SM, Katz A, Hoffer LJ, Levine M. Intravenously administered vitamin C as cancer therapy: three cases. CMAJ. 2006 Mar 28;174(7):937-42. http://www.ncbi.nlm.nih.gov/pubmed/16567755
7.Loria CM, Klag MJ, Caulfield LE, Whelton PK. Vitamin C status and mortality in US adults. Am J Clin Nutr.2000 Jul;72(1):139-45. http://ajcn.nutrition.org/content/72/1/139.abstract?ijkey=5b9197f8f0c3a6617746a9e4da79426faf94c17d&keytype2=tf_ipsecsha
8.Yeom CH, Jung GC, Song KJ. Changes of terminal cancer patients’ health-related quality of life after high dose vitamin C administration. J Korean Med Sci. 2007 Feb;22(1):7-11. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2693571/
9.Nutritive Value of Foods, United States Department of Agriculture
10.Francescone MA, Levitt J. Scurvy masquerading as leukocytoclastic vasculitis: a case report and review of the literature. Cutis. 2005 Oct;76(4):261-6. http://www.ncbi.nlm.nih.gov/pubmed/16315563?dopt=Abstract
11.Deicher R, Hörl WH. Vitamin C in chronic kidney disease and hemodialysis patients. Kidney Blood Press Res. 2003;26(2):100-6. http://www.ncbi.nlm.nih.gov/pubmed/12771534%20?dopt=Abstract
12.Hovdenak N, Haram K. Influence of mineral and vitamin supplements on pregnancy outcome. Eur J Obstet Gynecol Reprod Biol.2012 Oct;164(2):127-32. http://www.ncbi.nlm.nih.gov/pubmed/22771225
13.Fishman SM, Christian P, West KP. The role of vitamins in the prevention and control of anaemia. Public Health Nutr. 2000 Jun;3(2):125-50. http://www.ncbi.nlm.nih.gov/pubmed/10948381
14.AREDS Research Group. Associations of mortality with ocular disorders and an intervention of high-dose antioxidants and zinc in the Age-Related Eye Disease Study. AREDS Report No. 13. Arch Ophthalmol. 122:716-726, 2004. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1473208/?report=abstract
15.Douglas RM, Hemilä H, Chalker E, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD000980. http://www.ncbi.nlm.nih.gov/pubmed/17636648
16.Mills E, Montori V, Perri D, Phillips E, Koren G. Natural health product-HIV drug interactions: a systematic review. Int J STD AIDS. 2005 Mar;16(3):181-6. http://www.ncbi.nlm.nih.gov/pubmed?term=15829016
17.Lee LS, Andrade AS, Flexner C. Interactions between natural health products and antiretroviral drugs: pharmacokinetic and pharmacodynamic effects. Clin Infect Dis. 2006;43:1052–9. http://www.ncbi.nlm.nih.gov/pubmed?term=16983620
18.Jacob RA, Sotoudeh G. Vitamin C function and status in chronic disease. Nutr Clin Care. 2002 Mar-Apr;5(2):66-74. http://www.ncbi.nlm.nih.gov/pubmed/12134712?dopt=Abstract
19.Routine Vitamin Supplementation to Prevent Cancer and Cardiovascular Disease, Topic Page. June 2003. U.S. Preventive Services Task Force. http://www.uspreventiveservicestaskforce.org/uspstf/uspsvita.htm
20.Nutritive Value of Foods, United States Department of Agriculture, Agricultural Research Service, Home and Garden Bulletin Number 72. May be accessed at:
https://www.ars.usda.gov/SP2UserFiles/Place/12354500/Data/SR25/nutrlist/sr25w401.pdf
21.Carr AC, Frei B.Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans. Am J Clin Nutr. 1999 Jun;69(6):1086-107. http://www.ncbi.nlm.nih.gov/pubmed/10357726
22.Fishman SM, Christian P, West KP. The role of vitamins in the prevention and control of anaemia. Public Health Nutr. 2000 Jun;3(2):125-50. http://www.ncbi.nlm.nih.gov/pubmed/10948381