Vitamin C (Ascorbic acid)

Content provided by the Faculty of the Harvard Medical School

Vitamin C (Ascorbic acid)

Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain vitamin C. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with their pharmacists or health care providers before starting.

Evidence

Scientists have studied vitamin C for the following health problems:

Unproven Uses

Vitamin C has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially very serious and even life-threatening. You should consult a health care provider before taking aloe for any unproven use.

Potential Dangers

Allergies

Side Effects

Vitamin C is generally regarded as safe in amounts found in foods. Vitamin C supplements are also generally regarded as safe in most individuals in recommended amounts, although side effects are rarely reported including nausea, vomiting, heartburn, abdominal cramps, and headache. Tooth erosion may occur from chronically chewing vitamin C tablets.

High doses of vitamin C have been associated with adverse effects, particularly at doses greater than 2000mg per day. These include kidney stones, severe diarrhea, nausea, and gastritis. Rarely, flushing, faintness, dizziness, and fatigue have been noted. Large doses may precipitate hemolysis (red blood cell destruction) in patients with glucose 6-phosphate dehydrogenase deficiency, and should be avoided. High doses of vitamin C should be avoided in people with conditions aggravated by acid loading, such as cirrhosis, gout, renal tubular acidosis, or paroxysmal nocturnal hemoglobinuria. Injected vitamin C may cause dizziness, faintness, injection site discomfort, and in high doses may lead to renal insufficiency (kidney function problems). In cases of toxicity due to massive ingestions of vitamin C, forced fluids and increased urination may be beneficial.

Healthy adults who take chronic large doses of vitamin C may experience low blood levels of vitamin C when they stop taking the high doses and resume normal intake. To avoid this potential complication, people who are taking high doses who wish to reduce their intake should do so gradually rather than suddenly. There are rare reports of scurvy due to tolerance or resistance following stopping long-term high-dose use, such as in infants born to mothers taking 400mg per day or greater throughout their pregnancy.

Pregnancy And Breast-Feeding

Vitamin C intake from food is generally considered safe during pregnancy. However, it is not clear if vitamin C supplementation in amounts exceeding Dietary Reference Intake recommendations is safe or beneficial. There are rare reports of scurvy due to tolerance/resistance in infants born to mothers taking 400mg per day or greater throughout their pregnancy. Vitamin C is present in breastmilk. Vitamin C intake from food is generally considered safe in breastfeeding mothers. Limited research suggests that vitamin C in breastmilk may reduce the risk of the development of childhood allergies. It is not clear if vitamin C supplementation in amounts exceeding Dietary Reference Intake recommendations is safe or beneficial.

Interactions

Interactions with drugs, supplements and other herbs have not been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with your health care provider or pharmacist before using herbs or dietary supplements.

Interactions With Drugs

Vitamin C may increase adverse effects associated with acetaminophen (Tylenol).

Vitamin C may increase adverse effects associated with aluminum-containing antacids such as aluminum hydroxide (Maalox, Gaviscon).

Vitamin C may increase blood levels and adverse effects of aspirin, whereas aspirin may decrease blood levels of vitamin C.

The effects of vitamin C may be decreased by barbiturates including phenobarbital (Luminal, Donnatal), pentobarbital (Nembutal), or secobarbital (Seconal).

Vitamin C supplementation may decrease levels of the drug fluphenazine and indinavir in the body.

There is limited case report evidence that high dose vitamin C may reduce side effects of levodopa therapy such as nausea or difficulties with coordination.

Nicotine products such as cigarettes, cigars, chewing tobacco, or nicotine patches may decrease the effects of vitamin C.

Estrogens taken by mouth may decrease the effects of vitamin C in the body. When taken together, vitamin C may increase blood levels of ethinyl estradiol.

The effects of vitamin C may be decreased by tetracycline antibiotics such as doxycycline (Vibramycin), minocycline (Minocin), or tetracycline (Sumycin).

Vitamin C in high doses appears to interfere with the blood thinning effects of warfarin by lowering prothrombin time (PT), as noted in case reports in the 1970s. Complications have not been reported (such as increased blood clots).

Interactions With Herbs And Dietary Supplements

When taken together, vitamin C may increase the absorption of iron in the gastrointestinal tract, although this effect appears to be variable and may not be clinically significant. Vitamin C may increase absorption of lutein vitamin supplements. Large doses of vitamin C may interfere with the absorption and metabolism of vitamin B12.

Dosing

The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. The appropriate dosing should be discussed with a health care provider before starting therapy; always read the recommendations on a product's label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas.

• Dosage forms: Vitamin C is available in multiple dosage forms including forms that you cn take by mouth (regular or sustained release) and intravenously (given by a healthcare practitioner through the vein). Forms that can be taken by mouth include 100-1000mg capsules or tablets, powders, liquids/oral solutions (for example, 1-4g/5mL).

• Food sources: Apples, asparagus, berries, broccoli, cabbage, melon (cantaloupe, honeydew, watermelon), cauliflower, citrus fruits (lemons, oranges), fortified breads/grains/cereal, kale, kiwi, potatoes, spinach, tomatoes.

Dietary Reference Intakes (DRIs):

Adults (Aged 18 Or Older)

Oral: Men older than 18-years-old is 90mg per day; for women older than 18-years-old is 75mg per day. Recently, some experts have questioned whether the recommended daily intake should be raised. Others have recommended higher intake in some individuals, such as smokers, in whom an additional 35mg per day has been recommended by some. Upper limit should not exceed 2000mg per day in men or women older than 18-years-old (including pregnant or breastfeeding women).

Children (Younger Than 18)

Oral: The AI for infants ages 0-6 months-old is 40mg per day, and for infants 7-12 months-old is 50mg per day. The DRI for children 1-3 years-old is 15mg per day; for 4-8 years-old is 25mg per day; for 9-13 years-old is 45mg per day; for 14-18 year-old males is 75mg per day; for 14-18 year-old females is 65mg per day; for 14-18 year-old pregnant females is 80mg per day; for 14-18 year-old breastfeeding females is 115mg per day. Recently, some experts have questioned whether recommended daily intakes should be raised. The upper limit (UL) has not been determined for infants ages 0-12 months, and vitamin C in this group should only be derived from food intake to avoid excess doses. The UL for children ages 1-3 years-old is 400mg per day; the UL for ages 4-8 years-old is 650mg per day; the UL for ages 9-13 years-old is 1200mg per day; the UL for ages 14-18 years-old is 1800mg per day (including pregnant or breastfeeding females).

Pregnant and Breastfeeding Women

Oral: For pregnant women older than 18-years-old is 85mg per day; for breastfeeding women older than 18-years-old is 120mg per day.

Scurvy/deficiency

Adults (Aged 18 Or Older)

Oral: Vitamin C administered by mouth or injection is effective for curing scurvy. In adults, 100-250mg by mouth four times daily for 1 week is generally sufficient to improve symptoms and replete body vitamin C stores. Some experts have recommended 1-2 grams per day for 2 days followed by 500mg per day for 1 week. Symptoms should begin to improve within 24-48 hours, with resolution within 7 days. Treatment should be under strict medical supervision. For asymptomatic vitamin C deficiency, lower daily doses may be used.

Children (Younger Than 18)

In children, 100-300mg per day by mouth in divided doses for 2 weeks has been used. Older or larger children may require doses closer to adult recommendations. If vitamin C is not available, orange juice may be used for infantile scurvy. Symptoms should begin to improve within 24-48 hours, with resolution within 7 days. Treatment should be under strict medical supervision. For asymptomatic vitamin C deficiency, lower daily doses may be used.

Plaque/calculus on teeth

Adults (Aged 18 Or Older)

Oral: Patients chewed five or 10 pieces of gum containing 60mg of vitamin C per day for a period of 3 months in one study.

Prevention of premature rupture of chorioamniotic membranes

Adults (Aged 18 Or Older)

Oral: 100mg of vitamin C per day has been studied.

Common cold prevention/treatment

Adults (Aged 18 Or Older)

Oral: For cold prevention, 200mg per day or higher has been used. For cold treatment, up to 1000-2000mg per day has been used.

Other

Adults (Aged 18 Or Older)

Dosing regimens of vitamin C with unproven effectiveness or safety include: 120-450mg per day for antioxidant effects; 500-2000mg prior to exercise for exercise-induced asthma prevention; 45-1000mg per day for atherosclerosis prevention; 3000mg per day for delayed-onset muscle soreness; 1000-2000mg per day for diabetes; 50mg per day for gastric ulcer; 300-3000mg per day for high cholesterol; 200mg per day for male infertility; 2000mg per day for sunburn protection; 3-12 grams per day for urine acidification; 1000-1500mg per day for wound healing.

Summary

Vitamin C (ascorbic acid) is a water-soluble vitamin which is necessary in the body to form collagen in bones, cartilage, muscle, and blood vessels, and aids in the absorption of iron. Dietary sources of vitamin C include fruits and vegetables, particularly citrus fruits such as oranges. Severe deficiency of vitamin C causes scurvy. Although rare, scurvy includes potentially severe consequences, and can cause sudden death. Scurvy is treated with vitamin C, and should be under medical supervision. Many uses for vitamin C have been proposed, but few have proven to be beneficial. In particular, research in asthma, cancer, and diabetes remain inconclusive, while no benefits have been found in the prevention of cataracts or heart disease. The use of vitamin C in prevention/treatment of the common cold and respiratory infections remains controversial, with ongoing research.

The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.

Resources

• Natural Standard: An organization that produces scientifically based reviews of complementary and alternative medicine (CAM) topics

• National Center for Complementary and Alternative Medicine (NCCAM): A division of the U.S. Department of Health & Human Services dedicated to research

Selected Scientific Studies: Vitamin C

Natural Standard reviewed more than 1500 articles to prepare the professional monograph from which this version was created.

Some of the studies are listed below:

1. Anonymous. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E and beta carotene for age-related cataract and vision loss. Arch Ophthalmol 2001; 119:1439-1452.

2. Auer BL, Auer D & Rodgers AL: Relative hyperoxaluria, crystalluria and haematuria after megadose ingestion of vitamin C. Eur J Clin Invest 1998; 28(9):695-700.

3. Aukerman D. Do vitamin C supplements reduce cardiovascular disease mortality? Am Fam Physician 2004;69(7):1723-1724.

4. Balcke P, Schmidt P, Zazgornik J et al: Ascorbic acid aggravates secondary hyperoxalemia in patients in chronic hemodialysis. Ann Intern Med 1984; 101:344-345.

5. Bass WT, Malati N, Castle MC et al: Evidence for the safety of ascorbic acid administration to the premature infant. Am J Perinatol 1998; 15:133-140.

6. Basu TK: Vitamin C-aspirin interactions. Int J Vitam Nutr Res Suppl 1982; 23:83-90.

7. Beitz R, Mensink GB, Fischer B. Blood pressure and vitamin C and fruit and vegetable intake. Ann Nutr Metab 2003;47(5):214-220.

8. Buttery JE, Boord S, Ludvigsen H. Ascorbate interference in the urinary screen for acetaminophen. Clin Chem 1988; 34:769.

9. Casanueva E, Ripoll C, Tolentino M, et al. Vitamin C supplementation to prevent premature rupture of the chorioamniotic membranes: a randomized trial. Am J Clin Nutr 2005;81(4):859-863.

10. Castello T, Girona L, Gomez MR, et al: The possible value of ascorbic acid as a prophylactic agent for urinary tract infection. Spinal Cord 1996; 34:592-593.

11. Chappell LC, Seed PT, Briley AL, et al. Effect of antioxidants on the occurrence of pre-eclampsia in women at increased risk: a randomised trial. Lancet 1999; 354(9181):810-816.

12. Chen WT, Yan HC, Yu FC. Vitamin C improves vascular resistance in patients with chronic renal failure. Kidney Int 2003;64(6):2325-2326.

13. Cohen HA, Neuman I, Nahum H. Blocking effect of vitamin C in exercise-induced asthma. Arch Pediatr Adolesc Med 1997; 151:367-370.

14. Conte D, Brunelli L, Ferrario L, et al. Effect of ascorbic acid on desferrioxamine-induced urinary iron excretion in idiopathic hemochromatosis. Acta Haematol 1984; 72:117-120.

15. Curhan GC, Willett WC, Rimm EB, et al. A prospective study of the intake of vitamins C and B6, and the risk of kidney stones in men. J Urol 1996; 155:1847-1851.

16. Daniel TA, Nawarskas J: Vitamin C in the prevention of nitrate tolerance. Ann Pharmacother 2000; 34:1193-1197.

17. Darlow BA, Buss H, McGill F, et al. Vitamin C supplementation in very preterm infants: a randomised controlled trial. Arch Dis Child Fetal Neonatal Ed 2005;90(2):F117-F122.

18. Dolske MC, Spollen J, McKay S, et al. A preliminary trial of ascorbic acid as supplemental therapy for autism. Prog Neuropsychopharmacol Biol Psychiatry 1993; 17:765-774.

19. Domingo JL, Gomez M, Llobet JM, et al. Effect of ascorbic acid on gastrointestinal aluminum absorption. Lancet 1991; 338:1467.

20. Douglas R, Hemila H, D'Souza R, et al. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 2004;(4):CD000980.

21. Doyle J, Verman HJ, Stevenson DK, et al. Does vitamin C cause hemolysis in premature newborn infants? Results of a multicenter double-blind, randomized, controlled trial. J Pediatr 1997; 130:103-109.

22. Fang JC, Kinlay S, Beltrame J et al: Effect of vitamins C and E on progression of transplant-associated arteriosclerosis: a randomised trial. Lancet 2002; 359:1108-1013.

23. Feldman EB, Gold S, Greene J et al: Ascorbic acid supplements and blood pressure: a four-week pilot study. Ann N Y Acad Sci 1992; 342-344.

24. Finley EB & Cerklewski FL: Influence of ascorbic acid supplementation on copper status in young adult men. Am J Clin Nutr 1983; 37:553-556.

25. Fitzpatrick RE & Rostan EF: Double-blind, half-face study comparing topical vitamin C and vehicle for rejuvenation of photodamage. Dermatol Surg 2002; 38(3):231-236.

26. Fotherby MD, Williams JC, Forster LA et al: Effect of vitamin C on ambulatory blood pressure and plasma lipids in older persons. J Hypertens 2000; 18(4):411-415.

27. Ghosh SK, Ekpo EB, Shah IU et al: A double-blind placebo-controlled parallel trial of vitamin C treatment in elderly patients with hypertension. Gerontology 1994; 40:268-272.

28. Giunta, JL. Dental erosion resulting from chewable vitamin C tablets. J Am Dent Assoc 1983; 107:253.

29. Grebe G, Martinez-Torres C & Layrisse M: Effect of meals and ascorbic acid on the absorption of a therapeutic dose of iron on ferrous and ferric salts. Curr Ther Res 1975; 17:382-397.

30. Halberstein RA, Abrahmsohn GM. Clinical management and control of alveolalgia ("dry socket") with vitamin C. Am J Dent 2003;16(3):152-154.

31. Halperin EC, Gaspar L, George S et al: A double-blind, randomized, prospective trial to evaluate topical vitamin C solution for the prevention of radiation dermatitis. Int J Radiat Oncol Biol Phys 1993; 26:413-416.

32. Hampl JS, Taylor CA, Johnston CS. Vitamin C deficiency and depletion in the United States: the Third National Health and Nutrition Examination Survey, 1988 to 1994. Am J Public Health 2004;94(5):870-875.

33. Hansten PD & Hayton WL: Effect of antacid and ascorbic acid on serum salicylate concentration. J Clin Pharmacol 1980; 20:326-331.

34. Hemila H. Vitamin C supplementation and respiratory infections: a systematic review. Mil Med 2004;169(11):920-925.

35. Hoppu U, Rinne M, Salo-Vaananen P, et al. Vitamin C in breast milk may reduce the risk of atopy in the infant. Eur J Clin Nutr 2005;59(1):123-128.

36. Hoyt CJ: Diarrhea from vitamin C. JAMA 1980; 244:1674.

37. Huh CH, Seo KI, Park JY, et al. A randomized, double-blind, placebo-controlled trial of vitamin C iontophoresis in melasma. Dermatology 2003;206(4):316-320.

38. Hume R, Johnstone JM & Weyers E: Interaction of ascorbic acid and warfarin. JAMA 1972; 219:1479.

39. Hunter DJ, Manson JE, Colditz GA et al: A prospective study of the intake of vitamins C, E, and A and the risk of breast cancer. N Engl J Med 1993; 329:234-240.

40. Jacobs EJ, Connell CJ, McCullough ML et al: Vitamin C, vitamin E, and multivitamin supplement use and stomach cancer mortality in the Cancer Prevention Study II cohort. Cancer Epidemiol Biomarkers Prev 2002; 11:35-41.

41. Kim MK, Sasaki S, Sasazuki S, et al. Long-term vitamin C supplementation has no markedly favourable effect on serum lipids in middle-aged Japanese subjects. Br J Nutr 2004;91(1):81-90.

42. Knodell RG, Tate MA, Akl BF et al: Vitamin C prophylaxis for posttransfusion hepatitis: lack of effect in a controlled trial. Am J Clin Nutr 1981; 34:20-23.

43. Lawton JM, Conway LT, Crosson JT et al: Acute oxalate nephropathy after massive ascorbic acid administration. Arch Intern Med 1985; 45:950-951.

44. Lee DH, Folsom AR, Harnack L, et al. Does supplemental vitamin C increase cardiovascular disease risk in women with diabetes? Am J Clin Nutr 2004;80(5):1194-1200.

45. Lee KW, Lee HJ, Kang KS et al: Preventive effects of vitamin C on carcinogenesis. Lancet 2002; 359:172.

46. Levine GN, Frei B, Koulouris SN et al: Ascorbic acid reverses endothelial vasomotor dysfunction in patients with coronary artery disease. Circulation 1996; 93:1107-1113.

47. Lingstrom P, Fure S, Dinitzen B, et al. The release of vitamin C from chewing gum and its effects on supragingival calculus formation. Eur J Oral Sci 2005;113(1):20-27.

48. Masaki KH, Losonczy KG, Izmirlian G et al: Association of vitamin E and C supplement use with cognitive function and dementia in elderly men. Neurology 2000; 54(2):1265-1272.

49. McAllister CJ, Scowder EB, Dewberry FL et al: Renal failure secondary to massive infusion of vitamin C. JAMA 1984; 252:1684.

50. Mitch WE, Johnson MW, Kirshenbaum JM et al: Effect of large oral doses of ascorbic acid on uric acid excretion by normal subjects. Clin Pharmacol Ther 1981; 29:318-321.

51. Moertel CG, Fleming TR, Creagen ET et al: High-dose vitamin C versus placebo in the treatment of patients with advanced cancer who have had no prior chemotherapy: a randomized double-blind comparison. N Engl J Med 1985; 312:137-141.

52. Morris JC, Beeley L & Ballantine N: Interaction of ethinyl estradiol with ascorbic acid in man. Br Med J 1981; 283:503.

53. Mullan BA, Young IS, Fee H et al: Ascorbic acid reduces blood pressure and arterial stiffness in type 2 diabetes. Hypertension 2002; 40:804-809.

54. Nakamoto Y, Motohashi S, Kasahara H et al: Irreversible tubulointerstitial nephropathy associated with prolonged, massive intake of vitamin C. Nephrol Dial Transplant 1998; 13:754-756.

55. Nam CM, Oh KW, Lee KH, et al. Vitamin C intake and risk of ischemic heart disease in a population with a high prevalence of smoking. J Am Coll Nutr 2003;22(5):372-378.

56. Nathens AB, Neff MJ, Jurkovich GJ et al: Randomized, prospective trial of antioxidant supplementation in critically ill surgical patients. Ann Surg 2002; 236(6):814-822.

57. Nyyssonen K, Parviainen MT, Salonen R et al: Vitamin C deficiency and risk of myocardial infarction: prospective population study of men from eastern Finland. Br Med J 1997; 314:634-638.

58. O'Brien RT: Ascorbic acid enhancement of desferrioxamine-induced urinary iron excretion in thalassemia major. Ann N Y Acad Sci 1974; 232:221-225.

59. O'Malley PG. Review: vitamin E, vitamin C, and possibly coenzyme Q10 are ineffective for preventing or treating cardiovascular disease. ACP J Club 2004;140(3):73.

60. Paleologos M, Cumming RG & Lazarus R: Cohort study of vitamin C intake and cognitive impairment. Am J Epidemiol 1998; 148(1):45-50.

61. Petersen EE, Magnani P. Efficacy and safety of vitamin C vaginal tablets in the treatment of non-specific vaginitis. A randomised, double blind, placebo-controlled study. Eur J Obstet Gynecol Reprod Biol 2004;117(1):70-75.

62. Raitakari OT, Adams MR, McCredie RJ et al: Oral vitamin C and endothelial function in smokers: short-term improvement, but no sustained beneficial effect. J Am Coll Cardiol 2000; 35(6):1616-1621.

63. Ram FS, Rowe BH, Kaur B. Vitamin C supplementation for asthma. Cochrane Database Syst Rev 2004;(3):CD000993.

64. Ramenghi U, Saracco P, Timeus F et al: Use of ascorbate for the treatment of refractory idiopathic thrombocytopenic purpura in children. Am J Pediatr Hematol Oncol 1991; 13:486-489.

65. Rees DC, Kelsey H & Richards JDM: Acute haemolysis induced by high dose ascorbic acid in glucose-6-phosphate dehydrogenase deficiency. Br Med J 1993; 306:841-842.

66. Riordan HD, Riordan NH, Jackson JA, et al. Intravenous vitamin C as a chemotherapy agent: a report on clinical cases. P R Health Sci J 2004;23(2):115-118.

67. Rolf C, Cooper TG, Yeung CH et al: Antioxidant treatment of patients with asthenozoospermia or moderate oligoasthenozoospermia with high-dose vitamin C and vitamin E: a randomized placebo-controlled, double-blind study. Hum Reprod 1999; 14(4):1028-1033.

68. Romney SL, Duttagupta C, Basu J et al: Plasma vitamin C and uterine cervical dysplasia. Am J Obstet Gynecol 1985; 151:976-980.

69. Rosenthal G: Interaction of ascorbic acid and warfarin. JAMA 1971; 215:1671.

70. Schorah CJ, Tormey WP, Brooks GH et al: The effect of vitamin C supplement on body weight, serum proteins, and general health of an elderly population. Am J Clin Nutr 1981; 34:871-876.

71. Schulz HU, Schurer M, Krupp S, et al. Effects of acetylsalicylic acid on ascorbic acid concentrations in plasma, gastric mucosa, gastric juice and urine--a double-blind study in healthy subjects. Int J Clin Pharmacol Ther 2004;42(9):481-487.

72. Sketris IS, Farmer PS & Fraser A: Effect of vitamin C on the excretion of methotrexate. Cancer Treat Rep 1984; 68:446-447.

73. Slain D, Amsden JR, Khakoo RA, et al. Effect of high-dose vitamin C on the steady-state pharmacokinetics of the protease inhibitor indinavir in healthy volunteers. Pharmacotherapy 2005;25(2):165-170.

74. Solzbach U, Hornig B, Jeserich M et al: Vitamin C improves endothelial dysfunction of epicardial coronary arteries in hypertensive patients. Circulation 1997; 96:1513-1519.

75. Steyn PS, Odendaal HJ, Schoeman J, et al. A randomised, double-blind placebo-controlled trial of ascorbic acid supplementation for the prevention of preterm labour. J Obstet Gynaecol 2003;23(2):150-155.

76. Tanaka H, Matsuda T, Miyagantani Y et al: Reduction of resuscitation fluid volumes in severely burned patients using ascorbic acid administration: a randomized prospective study. Arch Surg 2000; 135:326-331.

77. Tanumihardjo SA, Li J, Dosti MP. Lutein absorption is facilitated with cosupplementation of ascorbic acid in young adults. J Am Diet Assoc 2005;105(1):114-118.

78. ter Riet G, Kessels AG & Knipschild PG: Randomized clinical trial of ascorbic acid in the treatment of pressure ulcers. J Clin Epidemiol 1995; 48:1453-1460.

79. Teramoto K, Daimon M, Hasegawa R, et al. Acute effect of oral vitamin C on coronary circulation in young healthy smokers. Am Heart J 2004;148(2):300-305.

80. Tielens JAE: Vitamin C for paroxetine- and fluvoxamine-associated bleeding. Am J Psychiatry 1997; 154:883-884.

81. Ting S, Mansfield LE & Yarbrough J: Effects of ascorbic acid on pulmonary functions in mild asthma. J Asthma 1983; 20:39-42.

82. Tomoda H, Yoshitake M, Morimoto K et al: Possible prevention of postangioplasty restenosis by ascorbic acid. Am J Cardiol 1996; 78:1284-1286.

83. Traikovich SS: Use of topical ascorbic acid and its effects on photodamaged skin topography. Arch Otolaryngol Head Neck Surg 1999; 125(10):1091-1098.

84. Traxer O, Huet B, Poindexter J, et al. Effect of ascorbic acid consumption on urinary stone risk factors. J Urol 2003;170(2 Pt 1):397-401.

85. Tsujikawa T, Kanauchi O, Andoh A, et al. Supplement of a chitosan and ascorbic acid mixture for Crohn's disease: a pilot study. Nutrition 2003;19(2):137-139.

86. Watanabe H, Kakihana M, Ohtsuka S et al: Randomized, double-blind, placebo-controlled study of ascorbate on the preventive effect of nitrate tolerance in patients with congestive heart failure. Circulation 1998; 97:886-891.

87. Watanabe H, Kakihana M, Ohtsuka S et al: Randomized, double-blind, placebo-controlled study of the preventive effect of supplemental oral vitamin C on attenuation of development of nitrate tolerance. J Am Coll Cardiol 1998; 31:1323-1329.

88. Zhang C, Williams MA, Frederick IO, et al. Vitamin C and the risk of gestational diabetes mellitus: a case-control study. J Reprod Med 2004;49(4):257-266.

89. Zollinger PE, Tuinebreijer WE, Kreis RW et al: Effect of vitamin C on frequency of reflex sympathetic dystrophy in wrist fractures: a randomised trial. Lancet 1999; 354(9195):2025-2028.

Last updated:	August 21, 2006