Monograph

Recognized as a strong defense during the cold and flu season, vitamin C is also necessary for the health of several body systems. Vitamin C can scavenge free radicals, aid tissue and wound repair, sustain cardiovascular function, and support cartilage and tendon health. NUTRAscriptives® Vitamin C is available in 500 mg and 1,000 mg tablets to meet your dietary needs.
 

Description

Vitamin C, also known as L-ascorbic acid, is a vital nutrient for humans. It is essential to a wide range of metabolic processes, including iron absorption and biochemical reactions. As a water-soluble antioxidant, vitamin C scavenges free radicals to reduce lipid peroxidation, protect DNA, and limit protein damage.

Research

Immune Function

Vitamin C concentrations quickly decline in the body during stress and infections. Unfortunately, this is when the body needs it the most to improve production of antimicrobial and natural killer cell activity, along with lymphocyte proliferation.[1] Several studies indicate vitamin C supplementation can restore the body's supply to shorten symptoms of infections.1

A sixteen-week study reviewed the effects of vitamins C (1 g per day) and E (200 mg per day) on strengthening the immune response in older women. Results indicated an increase in lymphocytes and decrease in lipid peroxides and cortisol levels suggesting these antioxidants can significantly improve immune function in older women.[2]

Vitamin C supplementation was administered to 168 volunteers between the winter months of November and February to assess the frequency of cold infections. Subjects taking vitamin C reported fewer colds and a shortened duration of cold symptoms, when compared to the placebo group.[3]

One study evaluated the effects of vitamin C (1000 mg) in relieving cold and flu symptoms among 252 students, in relation to 463 students that took traditional cold/flu therapies. Subjects taking vitamin C reported that ill symptoms decreased by 85%, when compared to the control group taking traditional therapies.[4]

Vitamin C may decrease the frequency of respiratory infections among individuals participating in extreme physical activity. A research review included studies that reviewed infections among children at a ski camp, long-distance runners, and military trainees. Results indicated vitamin C significantly reduced the frequency of infections in all three studies.[5] The same researcher reviewed twelve more studies in regards to vitamin C intake and respiratory ailments. The review concluded that vitamin C had a significant impact on reducing cold symptoms in subjects, while individuals were under heavy physical stress.[6]

Antioxidant Activity

Vitamin C has strong antioxidant activities that benefit cellular immunity. A combination of vitamin C and N-acetylcysteine might offset cellular dysfunction, as the proliferation of lymphocytes increased among patients with weakened immunity.[7] Research suggests that vitamin C is not dose-dependent in maintaining cellular immunity. One study gave 500, 1,000, or 5,000 mg of vitamin C to 20 healthy subjects finding antioxidant activity increased in all three doses.[8]

The antioxidant activity in vitamin C has been shown to reduce inflammation, as it was observed in 84 subjects with pancreatic inflammation. Results indicated the antioxidant activity in vitamin C blocked the formation of lipid peroxidation in the blood and improved cellular immune function to alleviate negative symptoms related to pancreatic dysfunction.[9]

Another benefit to vitamin C's antioxidant function includes a reduction in oxidative damage. A four-week study found vitamin C (500 mg per day) and E (182 mg per day) had beneficial effects on reducing oxidative DNA damage in male smokers.[10]

Cardiovascular Health

Vitamin C is a beneficial antioxidant to support healthy arteries and endothelial function (function of interior blood vessel cells). It can hinder the acceleration of stiff arteries that develop with endothelial dysfunction. Vitamin C (2,000 mg) was given to subjects with smoking-induced arterial stiffness finding supplementation reduced endothelial dysfunction and improved arterial flexibility.[11]

Vitamin C continues to benefit proper endothelial function by normalizing homocysteine levels (a dangerous amino acid). One study gave 17 healthy subjects vitamin C finding it reduced the formation of oxidative stress that augments homocysteine levels.[12]

The formation of nitric oxide is necessary for proper endothelial function, as a deficiency is related to arterial stiffness and free radical growth. One study found a reduction in these negative effects occurred six hours after a single dose of vitamin C (2,000 mg) was given to healthy male subjects.[13]

Furthermore, a study evaluated the effects of vitamin C (2,000 mg, three times per day) on nitrate tolerance in 24 patients with heart ailments and 24 healthy subjects. Researchers concluded vitamin C was a helpful addition to traditional therapy in preventing nitrate tolerance among individuals with heart ailments.[14]

Vitamin C and E may work to balance cholesterol levels, as a three-year study with 440 male and female subjects observed cardiovascular benefits with this combination. Researchers concluded the combination hindered the progression of cardiovascular ailments in subjects with abnormal cholesterol.[15]

A six-month study gave 40 subjects 500 mg of vitamin C to observe the effects on blood pressure and plasma lipids. Results indicated abnormal blood pressure was reduced supporting normal blood pressure function.[16]

Several women (85,118) participated in a longitudinal study on vitamin C intake and cardiovascular health. After 16 years, a follow-up discovered women taking vitamin C were less likely to develop cardiovascular ailments.[17]

Bone Health

Vitamin C is a required cofactor for collagen synthesis in normal bone development. One study reviewed the effects of vitamin C (100 mg) and calcium (500 mg) on bone mineral density in 775 postmenopausal women (45 to 64 years old) that took the nutritional combination or a placebo. Results indicated bone mineral density was significantly maintained in women taking the vitamin C/calcium combination when compared to the placebo group.[18]

Another study observed the relationship of vitamin C on bone mineral density in 277 postmenopausal women already taking a vitamin C supplement. Bone mineral density was greatest in subjects taking a combination of calcium, estrogen, and vitamin C.[19]

Researchers explored the benefits of vitamin C on bone mineral density in adolescents and older women finding positive benefits in bone mineral density existed in subjects with vitamin C rich diets.[20]

Tissue & Wound Healing

Vitamin C has shown promise in accelerating the healing process in tissue and bones. A study evaluated the combined effects of arginine (9g), vitamin C (500 mg), and zinc (30 mg) in 16 patients with ulcers. Results indicated healing significantly improved in patients taking these combined nutrients.[21]

An animal study reviewed the effects of vitamin C on healing fractures in 80 aged mice. The study found that vitamin C increased the healing process in aged mice after five weeks of treatment.[22] Another animal study found rats went through an accelerated healing process when taking a vitamin C supplement.[23]

Additional Information – Dosage & Interactions

Suggested Use

As a dietary supplement, take one tablet daily, or as directed by a physician.

Dosage

Up to 5,000 mg per day

Precautions

The maximum safe dosage of this supplement has not been determined for children, pregnant or nursing women, or those with severe liver or kidney disease. As with all supplement regimens, please consult your physician prior to use.

Stomach upset including nausea, diarrhea, abdominal cramps may occur in large doses due to unabsorbed vitamin C passing through the intestines.

Drug Interactions

Consult your physician before taking Vitamin C if you are taking the following medications.

Aluminum-containing antacids, Aspirin (impairs vitamin C), Chemotherapeutic agents, Estrogen, or Indinavir.

*Statements made herein have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

References

[1] Wintergerst, ES, Maggini, S, Hornig, DH. Immune-enhancing role of vitamin C and zinc and effect on clinical conditions. Ann Nutr Metab. 2006; 50(2):85-94.

[2] De La Fuente, M, Ferrandez, MD, et al. Immune function in aged women is improved by ingestion of vitamins C and E. Can J Physiol Pharmacol. 1998 Apr; 76(4):373-380.

[3] Van, SM, Josling, P. Preventing the common cold with a vitamin C supplement: a double-blind, placebo-controlled survey. Adv Ther. 2002 May; 19(3):151-159.

[4] Gorton, HC, Jarvis, K. The effectiveness of vitamin C in preventing and relieving the symptoms of virus-induced respiratory infections. J Manipulative Physiol Ther. 1999 Oct; 22(8):530-533.

[5] Hemila, H. Vitamin C and common cold incidence: a review of studies with subjects under heavy physical stress. Int J Sports Med. 1996 Jul; 17(5):379-383.

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

[7] Muller, F, Svardal, AM, Nordov, I, et al. Virological and immunological effects of antioxidant treatment in patients with HIV infection. Eur J Clin Invest. 2000 Oct; 30(10):905-914.

[8] Vojdani, A, Bazargan, M, et al. New evidence for antioxidant properties of vitamin C. Cancer Detect Prev. 2000; 24(6):508-523.

[9] Du, WD, Yuan, ZR, Sun, J, et al. Therapeutic efficacy of high-dose vitamin C on acute pancreatitis and its potential mechanisms. World J Gastronenterol. 2003 Nov; 9(11):2565-2569.

[10] Moller, P, Viscovich, M, et al. Vitamin C supplementation decreases oxidative DNA damage in mononuclear blood cells of smokers. Eur J Nutr. 2004 Oct; 43(5):267-274.

[11] Katayama, Y, Shige, H, et al. Oral vitamin C ameliorates smoking-induced arterial wall stiffness in healthy volunteers. J Atheroscler Thromb. 2004; 11(6):354-357.

[12] Chambers, JC, McGregor, A, et al. Demonstration of rapid onset vascular endothelial dysfunction after hyperhomocysteinemia: an effect reversible with vitamin C therapy. Circulation. 1999 Mar; 99(9):1156-1160.

[13] Wilkinson, IB, Megson, IL, MacCallum, H, et al. Oral vitamin C reduces arterial stiffness and platelet aggregation in humans. J Cardiovasc Pharmacol. 1999 Nov; 34(5):690-693.

[14] Watanabe, H, Kakihana, M, 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 May; 31(6):1323-1329.

[15] Salonen, RM, Nyyssonen, K, Kaikkonen, J, et al. Six-year effect of combined vitamin C and E supplementation on atherosclerotic progression: the Antioxidant Supplementation in Atherosclerosis Prevention (ASAP) Study. Circulation. 2003 Feb 25; 107(7):947-953.

[16] Fotherby, MD, Williams, JC, Forster, LA, Craner, P, Ferns, GA. Effect of vitamin C on ambulatory blood pressure and plasma lipids in older persons. J Hypertens. 2000 Apr; 18(4):411-415.

[17] Osganian, SK, Stampfer, MJ, et al. Vitamin C and risk of coronary heart disease in women. J Am Coll Cardiol. 2003 Jul; 42(2):246-252.

[18] Hall, SL, Greendale, GA. The relation of dietary vitamin C intake to bone mineral density: results from the PEPI study. Calcif Tissue Int. 1998 Sep; 63(3):183-189.

[19] Morton, DJ, Barrett-Connor, EL, Schneider, DL. Vitamin C supplement use and bone mineral density in postmenopausal women. J Bone Miner Res. 2001 Jan; 16(1):135-140.

[20] Prynne, CJ, Mishra, GD, O'Connell, MA, et al. Fruit and vegetable intake and bone mineral status: a cross sectional study in 5 age and sex cohorts. Am J Clin Nutr. 2006 Jun; 83(6):1420-1428.

[21] Desneves, KJ, Todorovic, BE, Cassar, A, Crowe, TC. Treatment with supplementary arginine, vitamin C and zinc in patients with pressure ulcers: a randomised controlled trial. Clin Nutr. 2005 Dec; 24(6):979-987.

[22] Alcantara-Martos, T, Delgado-Martinez, AD, Vega, MV, et al. Effect of vitamin C on fracture healing in elderly Osteogenic Disorder Shionogi rats. J Bone Joint Surg Br. 2007 Mar; 89(3):402-407.

[23] Yilmaz, C, Erdemli, E, Selek, H, et al. The contribution of vitamin C to healing of experimental fractures. Arch Orthop Trauma Surg. 2001 Jul; 121(7):426-428.