According to the Mayo Clinic, the recommended daily amount (RDA) for vitamin C is 65 to 90 mg with an upper limit of 2,000 mg. This RDA is intended to prevent scurvy, a fatal disease caused by Vitamin C deficiency. They further state that while megadoses are unlikely to cause serious harm, certain side effects might be experienced – e.g., diarrhea, nausea, heartburn, cramping, headache, insomnia.
Decades ago, Dr. Linus Pauling – a two-time Nobel prize winning biochemist – took these recommendations to task. In Vitamin C, the Common Cold, and the Flu, he cited multiple randomized, double-blind, placebo-controlled studies in which elevated intake of vitamin C significantly reduced the frequency, severity, and duration of colds and flus.
How does a cold or flu virus work?
Viruses cause the common cold and the flu (among other things). They are teeny, tiny microorganisms that worm their way into the body at the cellular level. They direct the cell’s biomachinery to produce lots of viral copies instead of the cell’s usual products. These copies then insinuate themselves into other cells and continue ramping up viral production. Along the way, they release poisons and toxins that make us feel lousy.
Our immune system fights back once a viral infection has taken hold. B cells generate virus-specific antibodies that bind to the microorganisms and stop them from replicating. They also tag viruses so that other cells called phagocytes know to destroy them. Viruses may also become inactive or destroyed by heat. (Note: Antibiotics only work on bacterial infections, not viral infections!)
So how might vitamin C work to ward off the common cold?
Vitamin C contributes to the formation of the colloidal substrate that binds tissues together. Pauling likens it to the rebar we use to lend strength and stability to a block of cement. Low Vitamin C weakens these substrates, making the cell more vulnerable to invasion. Vitamin C may also be implicated in the production and activation of interferons that inhibit viral production.
Infection-fighting leukocytes need Vitamin C to render them effective at destroying pathogens. Regular ingestion of Vitamin C keeps them in an appropriate state of readiness and may increase their motility. Levels deplete when combatting active infections. Therefore, an extra measure of Vitamin C may be required at such times to keep them in good working order.
Pauling notes that Vitamin C has been shown to deactivate herpes virus, vaccinia virus, hepatitis virus, bacterial viruses, and others. However, the rate of inactivation is proportional to dosage. One needs a large enough dose to generate favorable results.
How much should I ingest as a vitamin supplement?
If a person eats at least 5-7 serving of fresh fruits and vegetables daily, he or she is likely to get sufficient Vitamin C to prevent scurvy. When cooking, it’s best to steam or microwave veggies lightly to minimize nutrient loss.
To reap the health-promoting advantages touted by Dr. Pauling, one needs 1000-2000 mg supplemental Vitamin C spread through the day to maintain optimal blood levels. A large dose all at once may have a laxative effect. He notes, however, that the optimal dose for each individual varies based on his or her genetic profile and general state of health.
Dr. Pauling notes that the larger to the dose of Vitamin C, the greater the elimination of Vitamin C in the urine. This fact has been used by his detractors to suggest that excess dosage is a waste of money. However, even at higher doses, a percentage of the intake continues to remain bioavailable. It still proves beneficial as an antioxidant and as an essential coenzyme for important biochemical reactions. Moreover, Vitamin C in urine may prevent bladder infections and bladder cancer.
Some folks have an allergic reaction to the fillers used in the manufacture of Vitamin C tablets. Therefore, Dr. Pauling advocates use of sodium ascorbate in powdered form. Beyond the benefits for those prone to allergy, this formulation creates a lower acidic load in the bloodstream.
Has anything changed in the 4 decades since the publication of Dr. Pauling’s book?
In “Criteria and Recommendations for Vitamin C Intake” published in January 2006 by the Journal of the American Medical Association, the authors demonstrated that recommended intake of Vitamin C could be increased up to 200 mg per day. No change appears to have been made in the RDA. However, as Dr. Douglas Gildersleeve, MD notes:
“Having worked as a researcher in the field, it is my contention that an effective treatment for the common cold, a cure, is available that is being ignored because of the monetary losses that would be inflicted on the pharmaceutical manufacturers, professional journals [as recipients of pharmaceutical advertising revenue], and doctors themselves.”