Vitamin C for Prevention

Mechanism of action: Vitamin C is required for immune system to function well. It enhances lymphocyte activity, enhances phagocytosis, increases chemotaxis of neutrophils, and possibly increases antibody and interferon production. Vitamin C is also an antioxidant.

How to use it: Daily doses of 200 mg or more taken during the peak of cold season, i.e., winter. Typical doses are 500 mg to 1500 mg daily. Keep in mind that the upper level for tolerable intake is 400 mg/day for children ages 1 to 3, 650 mg/day for children ages 4 to 8, 1,200 mg/day for children ages 9 to 13, 1,800 mg/day for teens ages 14 to 18, and 2,000 mg/day for individuals 19 years and older.

Products to use: ConsumerLab.com purchased 29 brands of vitamin C-containing products: 27 for adults and 2 for children. All of the 29 products tested met their claims for vitamin C and all applicable pill forms could disintegrate properly for absorption. Examples of tested products include CVS Pharmacy Vitamin C, Nature Made Vitamin C, and Emergen-C.

Results to expect: when taken prior to the onset of cold symptoms, 8% decrease in illness duration for adults and 13.5% decrease for children based on 30 different trials. Fifteen trials showed decreases in symptom severity and days confined to the home. It does not decrease the incidence of colds in the general population, but in groups under stress; the relative risk reduction for developing a cold is 50%.

Side effects: GI symptoms such as nausea, vomiting, heartburn, abdominal pain, and diarrhea. Doses greater than two grams can lead to an osmotic diarrhea.