by Marcia Zimmerman, C.N.
Widespread vitamin C deficiencies
Many well-respected experts such as Emanuel Cheraskin MD, DND, contend that vitamin C deficiencies are widespread, but not to the extent of causing scurvy. Dr. Cheraskin lists capillary fragility as the chief cause of symptoms including frequent nosebleeds, bleeding gums and black and blue spots on the skin. In addition, low intake of vitamin C can lead to joint weakness, skin aging, cognitive dysfunction, reduced stress tolerance, atherosclerosis, cataracts, impaired immune function, and cancer.
Protect your eyes
Vitamin C, being a water soluble antioxidant, protects body fluids such as saliva, blood, lymph, intra and intercellular fluids, and those fluids that surround the lens of the eye. A recent study headed by Dr. Allen Taylor of Tufts University found that women who had daily intakes of 362 mg or more of vitamin C had a 57 percent lower risk of developing cataracts by age 60 than women whose daily intakes were less than 140 mg. In older women and men, high intakes of vitamin C have been shown to delay the onset of cataract and reduce its severity.
Cardiovascular protection
Vitamin C keeps artery walls flexible and prevents the oxidation of cholesterol, which helps prevent arterial plaque buildup and clot formation. A study of 5,197 people living in Rotterdam, Netherlands, many of them smokers, showed that those with the lowest vitamin C intake (less than 95 mg daily) from diet and supplements were 34 percent more likely to have a stroke than those with higher vitamin C intakes. Smokers in this group appeared to reap the greatest benefits, presumably because vitamin C is a potent scavenger of smoke-induced free radicals. A team of Harvard scientists studied the effects of vitamin C supplements vs diet among 85,118 nurses. Those who took a vitamin C supplement had a significantly lower risk of cardiovascular disease than the nurses who got vitamin C from diet alone.
Forms of vitamin C
The most common form of vitamin C is ascorbic acid. However, many supplements contain esterified forms such as calcium ascorbate, mixed mineral ascorbates and Ester-C. Minerals "buffer" the acidity of vitamin C, are better tolerated by some individuals, and as ascorbates, they are highly bioavailable.
Vitamin C formulas often contain flavonoids or bioflavonoids (citrus extracts), which enhance effectiveness. One study showed that a natural citrus extract containing flavonoids administered along with vitamin C reduced triglycerides and cholesterol oxidation in 26 men, some of whom had high cholesterol. The benefits did not occur when vitamin C alone was given.
How much C do you need?
The current daily requirement for vitamin C is 60 mg. However, many experts contend this if far too low to prevent vitamin C deficiency, particularly among smokers and others exposed to environmental toxins. A daily dose of 120 mg has been suggested as the basic amount needed to prevent sub-clinical scurvy with doses up to 1,000 mg daily recommended for those who want to maintain optimum health. This assumes that other antioxidants and vitamin E are available from diet and supplements to help prevent the destruction of vitamin C.
Selected Sources
- Cheraskin, E; et al., Relationship of Vitamin C and Skin Symptoms and Signs Journal of the CCA, 1978.
- Ibid. How Common is Vitamin C Deficiency? Journal of Alternative Medicine, 1986.
- Cass, H.; English, J.; User's Guide to Vitamin C North Bergen, NJ, Basic Health Publ. 2002.
- Krinsky, N; et al.; Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium and Carotenoids. Washington, D.C., National Academy Press 2000.
- Padayatty, SJ; et al.; Vitamin C as an Antioxidant: Evaluation of Its Role in Disease Prevention Journal of the American College of Nutrition 2003;22: 18-35.
- Barclay, L.; Diet Rich in Vitamin C Decreases Stroke Risk Medscape Medical News, 2003.
- Osganian, SK.; et al.; Vitamin C and Risk of Coronary Heart Disease in Women J Am Coll Cardiol 2003;16:246-52.
- Taylor, A,; et al.; Long-Term Intake of Vitamins and Carotenoids and Odds of Early Age-related Cortical and Posterior Subcapsular Lens Opacities Am J Clin Nutr 2002;75:540-9.
- Vojdani, A.; Ghoneum, M.; In Vivo Effect of Ascorbic Acid on Enhancement of Human Natural Kill Cell Activity Nut Res 1993;13:753-764.
- Brody, S.; et al.; A Randomized Controlled Trial of High Dose Ascorbic Acid for Reduction of Blood Pressure, Cortisol, and Subjective Response to Psychological Stress Psychopharmacology 2002;159:319-24.
- 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;69:1086-107.
- Vinson JA.; Jang, J.; In Vitro and In Vivo Lipoprotein Antioxidant Effect of a Citrus Extract and Ascorbic Acid on Normal and Hypercholesterolemic Human Subjects J Med Food 2001;4:187-192.
- Fay, MJ.; Verlangieri, AJ.; Stimulatory Action of Calcium L-Threonate on Ascorbic Acid Uptake by a Human T-Lymphoma Cell Line Life Sciences 1991;49:1377-1381.
- Morris, MC; et al., Vitamin E and Cognitive Decline in Older Persons Arch Neurol 2002;59:1125-32.
- Morris, M.; et al.; Vitamin E and Vitamin C Supplement Use and Risk of Incident Alzheimer Disease. Alzheimer Disease and Associated Disorders 1998;12:121-6.
- Grundman, M.; Vitamin E and Alzheimer Disease: The Basis for Additional Clinical Trials Amer J Clin Nutr 2000;71:630S-6S.
- Astley, S.; et al.; Vitamin Supplementation and Oxidative Damage to DNA and Plasma LDL in Tupe 1 Diabetes Diabetes Care 1999;22:1626-1631.
- Manning PJ; et al.; Effect of High-Dose Vitamin E on Insulin Resistance and Associated Parameters in Overweight Subjects Diabetes Care 2004;27:2166-71.
- Patterson, R,; et al.; Vitamin Supplements and Cancer Risk: The Epidemiologic Evidence Cancer Causes and Control 1997;8:786-802.
- Helzlsouer, KJ.; et al.; Association Between alpha-Tocopherol, gamma-Tocopherol, Selenium and Subsequent Prostate Cancer J Natl Cancer Inst 2000;92:
