The Vitamin C RDA is less than 100 mg per day. Two pharmacology professors say that’s not enough. Find out why.
The controversy over the Vitamin C RDA (recommended daily allowance) began with the publication of Linus Pauling's book, Vitamin C and the Common Cold. Now, Steve Hickey, PhD, and Hillary Roberts, PhD, pharmacology professors and graduates of the University of Manchester in Britain, are presenting their own challenges to the established Vitamin C RDA, which is 75 and 90 milligrams for males and females respectively.
In their book Ascorbate, The Science of Vitamin C, Hickey and Roberts point out some biological flaws to justify why they think the vitamin C RDA is too low. The researchers cite government organizations — like the Institute of Medicine (IM) and the National Institutes of Health (NIH) — failure to take into account the short half life of Vitamin C.
WHAT IS HALF LIFE AND HOW DOES IT AFFECT THE VITAMIN C RDA?
The half life of any substance is the time it takes for half of it to be removed from the body. Vitamin C's half life is only about 30 minutes in blood plasma, but the Vitamin C RDA was established assuming a 12–24-hour half life.
Due to the short half life of Vitamin C, many studies make the conclusion that high-dose supplemental vitamin C is ineffective. Drs. Hickey and Roberts state that due to its rapid deterioration, a very high dose of Vitamin C would not achieve the same concentration in the blood serum over time as staggered doses.
VITAMIN C RDA IS JUST ENOUGH TO PREVENT SCURVY
The two researchers contend the Vitamin C RDA is intended to set a level of nutrient consumption that would prevent Vitamin C deficiency disease scurvy among the vast majority of the population. Their research, however, shows that a large percentage of thepopulation requires more than the Vitamin C RDA, including:
- Smokers
- Estrogen and birth control pill users
- Diabetics
- Pregnant females
-
People taking aspirin
THE VITAMIN C RDA MAY NOT BE ENOUGH FOR OPTIMAL HEALTH
NIH researchers continue to maintain that no more than 200 milligrams of oral Vitamin C is required for human health and that a diet which includes the recommended five servings of fruits and vegetables would provide adequate Vitamin C.
But less than 10% of the US population consumes five servings of plant foods daily. The National Cancer Institute abandoned their five/day recommendation in favor of a nine/day servings of fruits and vegetables when they realized five servings did not provide the proper dietary intake of Vitamin C and other essential vitamins. Dr. Hickey has called for the IM and NIH to retract the current Vitamin C RDA or provide scientific justification for their recommendation.
HOW MUCH VITAMIN C DO YOU ACTUALLY NEED?
Obviously the Vitamin C RDA is under considerable debate. The closest thing to certainty is 75–90 mg/day should be enough to avoid fatal deficiency if no other conditions depleting Vitamin C are present. And no organization has declared an upper limit to Vitamin C consumption.
