Vitamin C and Common cold
Many claims have been made about the role of vitamin C (ascorbic acid) in regard to the prevention and treatment of the common cold. Since 1970, there have been over twenty double-blind studies designed to assess what role vitamin C can play in the common cold. In the majority of the studies vitamin C supplementation produced a decrease in either duration or symptom severity. Analysis of all studies indicates that vitamin C at a dosage of 1-6 g daily decreased the duration of the cold episodes by 0.93 days, or roughly 21 percent.
Since the transport of vitamin C into cells is facilitated by insulin, most diabetics suffer from a deficiency of intracellular vitamin C. A relative vitamin C deficiency exists in many diabetics despite an adequate dietary intake of the vitamin, as the diabetic simply needs more vitamin C. Failure to correct a chronic, latent intracellular vitamin C deficiency will lead to a number of problems for the diabetic, including increased capillary permeability, poor wound healing, elevation in cholesterol levels, and depressed immune system.
Gingivitis and periodontal disease
Vitamin C plays a major role in preventing gingivitis and periodontal disease. Vitamin C helps maintain the integrity and immune function of the gums. Deficiency of vitamin C is associated with inflamed and bleeding gums.
Heart disease (atherosclerosis) prevention
A high dietary intake of vitamin C has been shown to significantly reduce the risk of death from heart attacks and strokes. There is some evidence that higher intakes of vitamin C are associated with decreased LDL cholesterol and higher levels of the protective HDL cholesterol. However, results from double-blind studies examining the benefit of high dosage vitamin C supplementation (usually 1,000 mg) on lowering total cholesterol while raising HDL cholesterol levels have been inconsistent. More recent studies have determined that only in subjects with low or marginal vitamin C status does high-dosage supplementation produce an effect.
High blood pressure
Population studies have shown that the higher the dietary intake of vitamin C, the lower the blood pressure. Several preliminary studies have shown a modest blood-pressure-lowering effect (e.g., a drop of 5 mm Hg systolic and diastolic) of vitamin C supplementation in people with mild elevations of blood pressure.
Low immunity and immune support
Vitamin C has been shown to enhance many different immune functions, including improving white blood cell function and activity and increasing interferon levels, antibody responses, antibody levels, secretion of thymic hormones, and integrity of collagen structures that serve as barriers to infection. Vitamin C also possesses many biochemical effects very similar to those of interferon, the body’s natural antiviral and anticancer compound. During times of infection and stress, vitamin C requirements increase. Double-blind studies have shown vitamin C
Vitamin C is critical to proper wound healing and may be helpful in preventing and treating pressure sores (bedsores) in the elderly. Up to 60 percent of all elderly hospital patients suffer from pressure sores. Analysis of vitamin C levels in patients admitted to a hospital for hip fracture indicated that patients who developed bedsores had vitamin C levels that were 50 percent lower than the patients who did not develop bedsores.
Vitamin C is available in a number of different forms – crystals, powders, capsules, tablets, timed-release tablets, and others. The actual type of vitamin C in these different forms can also vary. Ascorbic acid is the most widely used (and least expensive) form. Buffered vitamin C, such as Easter-C, is sodium ascorbate, magnesium ascorbate, calcium ascorbate, or potassium ascorbate. Buffered vitamin C is popular because the acid content of nonbuffered ascorbic acid may bother some people’s stomachs. However, absorption studies have not shown any type of buffered vitamin C to be better absorbed tan ascorbic acid. Taking vitamin C with bioflavonoids may offer benefits in absorption, but only if the product contains bioflavonoids in amounts equal to or greater than the amount of vitamin C.
Food and Nutrient Interactions
Vitamin C increases the absorption of iron and copper. It may also interfere with the blood test for vitamin B12. Vitamin C is intricately involved with other nutritional antioxidants, especially vitamin E, selenium, and beta-carotene.
In healthy individuals, a daily dosage of 100 to 500 mg is believed to be sufficient. However, higher dosages may be necessary in certain health conditions such as asthma, diabetes, and cataracts, and in infectious conditions including the common cold. In these health conditions the dosage range is typically 500 to 2000 mg daily. The Tolerable Upper Level Intake (UL) has been set at 2 g daily for men and women over nineteen years of age.