By Greg Arnold, DC, CSCS, October 30, 2009, abstracted from “Immune-enhancing role of vitamin C and zinc and effect on clinical conditions” in the Annals of Nutrition and Metabolism
Vitamin C first came to be known for helping prevent “scurvy”. This condition is characterized by general weakness, anemia, gum disease (gingivitis), and skin bruising/bleeding (1). Vitamin C is a water-soluble vitamin, meaning it dissolves in water and is not stored in fat in the body. Because the body cannot store vitamin C and leftover amounts leave the body through the urine, it important to get a continuous supply of such vitamins in your diet (2). Zinc is a trace element that plays a role in cell division, cell growth, wound healing, the breakdown of carbohydrates, and for the senses of smell and taste (3).
A review (4) has found both vitamin C and zinc to elicit significant health benefits in three areas:
OXIDATIVE STRESS. Cell damage by free radicals has been implicated as “a major contributing factor” in the development of chronic diseases such as cardiovascular disease (which costs our healthcare system $473 billion per year (5)), cancer ($219 billion per year (6)), and cataracts ($3.4 billion per year (7), respectively (8). Research has shown that not only does vitamin C prevent oxidative damage to fats, proteins, and DNA (9), but it also helps regenerate other important antioxidants such as glutathione and vitamin (10). As for zinc, it helps prevent the formation of dangerous free radicals called “hydroxyl radicals” by helping block binding sites for copper and iron on cell membranes (11).
INFECTIOUS DISEASES. The common cold costs our healthcare system $40 billion each year (12). While research has not shown vitamin C to prevent the common cold, 600 mg vitamin C per day allows patients “to cope better with the oxidative stress response resulting from strenuous exercise, significantly decreasing upper respiratory tract infections (13). For zinc, research has shown that taking zinc lozenges containing 12.8 mg of zinc acetate every 2–3 hours after the onset of a cold helped reduce the duration of the cold by 45% (4.5 vs. 8.1 days), cough by 49% (3.1 vs. 6.3 days), and nasal discharge by 29% (4.1 vs. 5.8 days) compared to placebo (14).
OVERALL IMMUNE SYSTEM HEALTH. Vitamin C in doses of 1-5 grams per day can help increase activity of immune system cells called "T lymphocytes" and "neutrophils (15) while 1 gram of vitamin C for 16 weeks “improved resistance to oxidative stress (16).” Regarding zinc, deficiency has been shown to impair immunity by decreasing activity of white blood cells called “macrophages” and neutrophils (17).
For the researchers, “Adequate intakes of vitamin C and zinc are essential for health.” The current RDA for vitamin C is 60 mg per day (18) and for zinc ranges from 2 mg per day in infants to 8 mg per day in adults (3).
Greg Arnold is a Chiropractic Physician practicing in Danville, CA. You can contact Dr. Arnold directly by emailing him at mailto:PitchingDoc@msn.com or visiting his web site at www.CompleteChiropracticHealthcare.com
1. “Scurvy” posted on www.nlm.nih.gov/medlineplus/ency/article/000355.htm
2. “Vitamin C” posted on www.nlm.nih.gov/medlineplus/ency/article/002404.htm
3. “Zinc in diet” posted on www.nlm.nih.gov/medlineplus/ency/article/002416.htm
4. Wintergerst ES. "Immune-enhancing role of vitamin C and zinc and effect on clinical conditions", Ann Nutr Metab 2006;50(2):85-94
5. “Cardiovascular Disease at a Glance” posted on www.cdc.gov/NCCDPHP/publications/AAG/dhdsp.htm
6. “Costs of Cancer” posted on www.cancer.org/docroot/MIT/content/MIT_3_2X_Costs_of_Cancer.asp
7. Steinberg EP, Javitt JC, Sharkey PD, et al. The content and cost of cataract surgery. Arch Ophthalmol 1993; 111: 1041–9
8. 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; 69: 1086–1107.
9. Ames BN, Shigenaga MK, Hagen TM: Oxidants, antioxidants, and the degenerative diseases of aging. Proc Natl Acad Sci USA 1993; 90: 7915–7922
10. Jacob RA: The integrated antioxidant system. Nutr Res 1995; 15: 755–766.
11. Powell SR: The antioxidant properties of zinc. J Nutr 2000; 130: 1447S–1454S
12. Fendrick AM. The economic burden of non-influenza-related viral respiratory tract infection in the United States. Arch Intern Med. 2003 Feb 24;163(4):487-94
13. Peters EM. Vitamin C supplementation reduces the incidence of postrace symptoms of upperrespiratory-tract infection in ultramarathon runners. Am J Clin Nutr 1993; 57: 170–174.
14. Prasad AS, Fitzgerald JT, Bao B, Beck FW, Chandrasekar PH: Duration of symptoms and plasma cytokine levels in patients with the common cold treated with zinc acetate. A randomized, double-blind, placebo-controlled trial. Ann Intern Med 2000; 133: 245–252.
15. Anderson R, Smit MJ, Joone GK, van Straden AM: Vitamin C and cellular immune functions: protection against hypochlorous acidmediated inactivation of glyceraldehyde-3phosphate dehydrogenase and ATP generation in human leucocytes as a possible mechanism of ascorbate-mediated immunostimulation. Ann NY Acad Sci 1990; 587: 34–48.
16. De la Fuente M, Fernandez MD, Burgos MS, Soler A, Prieto A, Miquel J: Immune function in aged women is improved by ingestion of vitamins C and E. Can J Physiol Pharmacol 1998; 76: 373–380.
17. Klug A, Schwabe JWR: Zinc ﬁ ngers. FASEB J 1995; 9: 597–604
18. “Vitamin C” posted on http://lpi.oregonstate.edu/infocenter/vitamins/vitaminC/