© Whole Foods Magazine

September 2005

The RDA for Vitamin C Is Invalid: New Information

An Interview with Bill Sardi

By Richard A. Passwater, Ph.D.


When the office telephone rang on Independence Day, which also fell on the weekend, I knew it should be answered. After all, it must be from a scientist/writer, as who else would be in the office on a national holiday? In this instance, the call came from Bill Sardi who had important news regarding the daily dietary need for vitamin C. Bill Sardi is a consumer health advocate and health journalist headquartered in San Dimas, CA. I have interviewed him about his books in this column before.

I told Bill that the vitamin C news was so important that our readers should see it as quickly as possible. Bill agreed and offered to relay the message to Dr. Steve Hickey. I told Bill there was no time to do even that much, as I was editing an interview at the very moment he called, and my deadline was the next day. If I wanted to get the information to our readers as fast as I could, I would have to interview Bill—now— about Dr. Hickeys findings. I usually insist on directly interviewing the scientists involved, but in this case time was of the essence. I will try to arrange an interview with Dr. Hickey later for an in-depth look at his findings.


Passwater: Bill, lets start at the beginning. What is the important news about our daily need for vitamin C?


Sardi: In a recent book, Ascorbate: The Science of Vitamin C (264 pages, copyright 2004, available as an online e-book at www.lulu.com/ascorbate, and also in soft cover), Drs. Steve Hickey and Hilary Roberts, pharmacology graduates of Manchester University in England, maintain the current Recommended Dietary Allowance (RDA) for vitamin C was established without proper scientific protocol and that millions of humans have suffered premature cataracts, arthritis, arterial disease and death because of miscalculations by vitamin C researchers. Given that most people are currently advised that high-dose vitamin C intake is worthless and may be problematic, this is certainly a startling report.


Passwater: Some of our readers may remember what I have written in this column about this, but please review for the benefit of new readers just how the RDA for vitamin C was established.


Sardi: There is a discussion of this topic in the Hickey/Roberts book. The U.S. Food & Nutrition Board has prepared the RDA since 1941. Hickey and Roberts claim the very idea of an RDA is based upon “outdated biological ideas.” The idea that a single dose of vitamin C is suitable for a large population should be abandoned, given that there are widespread individual variables which were outlined by Roger Williams in his classic 1956 book, Biochemical Individuality. In states of biological stress, such as illness, emotional or physical strain, exposure to solar radiation and cancer, living tissues require more vitamin C. The need for vitamin C is dynamic and requires repeated supplementation.


Passwater: What is the major flaw in the RDA intake level for vitamin C?


Sardi: Drs. Hickey and Roberts take Institute of Medicine (IM) and National Institutes of Health (NIH) researchers to task for failing to calculate the half-life of ascorbic acid. The half-life is the time vitamin C takes to disappear from human tissues. In humans, the half-life for vitamin C is about 30 minutes. NIH researchers established the current RDA based upon tests conducted 12 hours (24 half-lives) after consumption. “To be blunt,” says Dr. Hickey, “the NIH gave a dose of vitamin C, waited until it had been excreted, and then measured blood levels.”

Because vitamin C is used up rapidly, a very high single dose of vitamin C would not achieve the same concentration in the blood serum over time as two divided lower doses. Drs. Hickey and Roberts claim many negative studies using high-dose vitamin C have failed to recognize this fact and have therefore mistakenly concluded that high-dose supplemental vitamin C is ineffective.

Furthermore, the RDA for vitamin C was established using studies of just seven and 15 individuals, certainly not enough to provide statistical power for an RDA intended for 280 million people. [Proceedings National Academy Sciences 3: 3704-09, 1996]


Passwater: Just the fact that that extremely small study has been given so much scientific weight appalls me. I commented on this before in this column during an interview with Dr. Balz Frei, the director of the Linus Pauling Institute at Oregon State University.

This small study, involving just a few healthy young men, was sufficient for the researcher, Dr. Levine, to suggest that the then existing RDA be raised. But he also called for larger studies, which were not performed. Dr. Levine did not suggest raising the RDA high enough based on his data. Furthermore, his study did not indicate what the optimal intake of vitamin C should be when the body is under bacterial or viral attack. The studies were on a few healthy young men isolated from the real world and thus isolated from exposure to new germs. The volunteers were confined to a metabolic ward-type of setting during the study and were not free-living.

The uptake of vitamin C in white blood cells is much greater when the immune system is responding to bacterial or viral attack, or in a person suffering from arthritis or diabetes. As Dr. Robert Cathcart and others have shown, there are five grams of vitamin C colds and 25 grams of vitamin C flu cases. This is why bowel tolerance to megadoses of vitamin C intake goes up during illness—the white blood cells are absorbing more of the vitamin C and thus less vitamin C remains in the bowel to cause loose stools or diarrhea.

Still, in Dr. Levines study, plasma saturation in these healthy young men wasnt achieved until 1,000 mg daily. It would be interesting to see what the vitamin C uptake is in healthy older persons and those fighting various illnesses. Plasma vitamin C levels increased even at doses greater than 200 mg of vitamin C per day. For example, at 200 mg of vitamin C per day, plasma levels were about 65 uM, at 1,000 mg per day, about 75 uM, and at 2,500 mg per day, about 85 uM. Furthermore, “tissues” claimed to be saturated at an intake of 100 mg per day of vitamin C were merely white blood cells, but no other tissues such as liver or brain. Thus, the study has its limitations. It is not an adequately comprehensive study on vitamin C pharmacokinetics and requirements in humans.

How did NIH researchers get themselves into such a situation?


Sardi: NIH researchers recently noted that intravenous vitamin C raises plasma concentrations 6.6 times above oral high-dose vitamin C supplementation. They conceded that the “role of vitamin C in cancer treatment should be reevaluated” in light of this study. This vindicates the work of Dr. Linus Pauling, who pioneered the use of intravenous vitamin C as a cancer treatment.

The study also revealed another overlooked fact—1,250 mg of oral vitamin C taken every four hours raised plasma concentrations to 134.8 micromols per liter of blood. [Annals Internal Medicine 140: 533-37, 2004] Oral vitamin C when given in divided high doses can achieve blood concentrations (greater than 73.8 micromole per liter), which are documented to reduce the risk of mortality from cancer and all causes of death by 57% to 62% respectively! [American Journal Clinical Nutrition 72: 139-45, 2000] Dr. Hickey says the NIH should have immediately issued retractions on its previously published papers and called for a fresh review of the RDA. They didn’t. NIH’s own data exposes the flaws in the RDA, a remarkable self-indictment that the NIH wasn’t quick to air in public.


Passwater: Has Dr. Hickey communicated directly with the Institutes of Medicine and the National Institutes of Health on this issue?


Sardi: Dr. Hickey says he has engaged the IM and NIH for the past year. The NIH has stopped responding to his e-mails. The failure of these health organizations to adequately respond to these challenges regarding the RDA for vitamin C over the past year prompted he and Dr. Roberts to publish their book.


Passwater: Do they deal with the saturation point for vitamin C?


Sardi: Drs. Hickey and Roberts, as well as many other vitamin C researchers, believe the idea of a “saturation point” for vitamin C in white blood cells is misleading and should be abandoned. Blood plasma concentrations are not indicative of the need for ascorbic acid in tissues throughout the rest of the body. NIH scientists continue to maintain that 200 mg of oral vitamin C achieves maximal concentration of vitamin C in blood plasma (approximately 60 to 70 micromoles per liter of blood) and anything above 200 mg is “nearly completely excreted in urine.” [Biofactors 15: 71-74, 2001] However, recent studies conducted by NIH reveal that repeated high-dose oral vitamin C can produce concentrations three times greater (220 micromoles per liter) than the so-called saturation level. [Annals Internal Medicine 140: 533-37, 2004]


Passwater: What is Drs. Hickey and Roberts recommendation for vitamin C intake for healthy humans?


Sardi: Because of the half-life problem, Drs. Hickey and Roberts emphasize divided doses of supplemental vitamin C throughout the day, as did Dr. Linus Pauling. Dividing the doses is more important than dosage, they say. They cautiously estimate a 160-pound healthy adult would require about 2,500 mg of vitamin C, lets say a 500 mg dose of vitamin C taken every three hours, or five times a day. Divided doses would likely overcome the diarrhea side effect that is sometimes experienced by vitamin C supplement users.


Passwater: Why do you feel that this information is so important that we are spending our holiday weekend talking about it?


Sardi: First, millions of Americans may have been misled by health authorities and received errant advice in their development of personal health regimens. The flawed science behind the RDA is now being revealed. You yourself have challenged the RDA concept over the years. Its just that this time Drs. Hickey and Roberts have pinned the scientists down on the particulars. Now the flawed science is in the open for everyone to examine. It is easily understood by consumers who ought to be quite angry over these revelations. Third, the worldwide trade agreement known as Codex, which would restrict essential nutrients in dietary supplements to certain amounts (the so-called safe upper limit) is based upon the RDA. I have sent an e-mail to the U.S. Codex delegation and asked them to cease approval of any Codex proposals in regard to dietary supplements until this RDA problem is resolved.

Passwater: Then there is the issue of blood levels versus tissue levels. They are not always directly related. What does Dr. Hickey say about this?


Sardi: There may be greater need for vitamin C in selected tissues throughout the body over and above that of the blood plasma, which is used to determine the so-called saturation point in humans. The brain levels of vitamin C are tenfold greater than blood plasma. The adrenal gland has high demand for vitamin C during periods of emotional or physical stress. The skin and the human eye are exposed to solar ultraviolet radiation and require more vitamin C during times of intense exposure. In 1991 there was a report in Current Eye Research that the provision of 2,000 mg of oral vitamin C raised ocular concentrations of vitamin C by 22%-32%, compared to when 148 mg of vitamin C was added to the diet. That report alone should have signaled researchers that the idea of a saturation point for ascorbate was flawed. Recall that we live in an era when physicians, pharmacists and researchers all repeat the false claim that consumers are wasting their money taking high-dose vitamin C since excessive amounts are excreted in the urine. Furthermore, a high-dose vitamin C regimen would literally serve as a cleanser for the bladder. The acidity from the vitamin C would kill off any bacteria and the risk for bladder cancer would diminish. This is a point that you have made in your own books about vitamin C.


Passwater: Some people miss the real importance of multi-functional vitamin C. Vitamin C is not just to prevent scurvy. Please give us a brief review of why vitamin C is so important in the human body.


Sardi: Vitamin C is key in the rebuilding of collagen, the goo between cells that is in continual need of replacement and repair. Collagen is a barrier against the spread of infection and malignancies. Vitamin C helps to control the blood capillaries. Low levels of vitamin C loosen the capillaries and permit serum, toxins, cellular debris or even red cells to pass into surrounding tissues, which results in inflammation and/or hemorrhage. Vitamin C regenerates glutathione, considered one of the master antioxidants in all living cells. By lending an electron, vitamin C also protects vitamin E from being oxidized. Living cells crave more vitamin C when they are distressed.

It is a central antioxidant nutrient, evidenced by the fact the human body used to produce it in great amounts. A genetic mutation that occurred long ago in human history, which was transferred to all succeeding human generations, inactivated the endogenous production of vitamin C. Four enzymes are required to convert blood sugar passing through the liver into vitamin C. Humans are missing the fourth enzyme, gulonolactone oxidase. Most mammals, except for fruit bats, guinea pigs, the primates and humans, make their own vitamin C. The gene responsible for the production of this enzyme has been located in the human genome, but it is mutated and nonfunctional, what is called a pseudogene.

The RDA for vitamin C may be more important than for other essential nutrients in the body, in particular because of the massive universal shortage caused by the genetic mutation that stopped endogenous synthesis in our forefathers.


Passwater: What can be done now to urge a review of the RDA for vitamin C?


Sardi: For the most part, the scientific community is not urging a review of the RDA for vitamin C. Health authorities have bought into the false claims of a RDA” and “saturation levels” without sufficient scrutiny. The very fact most mammals make high-dose vitamin C on their own without side effect should cause researchers to question any precautions over high-dose human consumption. All this is now coming unraveled with Drs. Hickey and Roberts new book.

The scientific community is going to have to be prodded into reviewing its own flawed science. The public, health advocates, health freedom organizations, and the natural products industry need to promote and distribute this new book, and they need to urge Congressional representatives to call for an immediate scientific explanation and review of the RDA for vitamin C by the National Institutes of Health and the Institutes of Medicine. Some involved parties may wish to contact the NIH and IM directly. I have posted instructions how to do this at my website—www.askbillsardi.com.

I have begun the letter-writing campaign by sending an e-mail to Senator Thomas Harkin (D-IA), asking him to contact the IM and NIH to demand their rationale for the current RDA for vitamin C. Ive also asked Senator Harkin to initiate legislation that would place an asterisk every time the RDA* is published which would indicate it is “*intended for healthy people only and does not indicate nutrient levels needed by the aged, smokers, diabetics, pregnant females, individuals taking certain medications and those who are ill.” The RDA gives many consumers the false impression that the RDA is all they need.


Passwater: My focus with vitamin C over the past 45 years has been with living better longer and the reduction of the risk of cancer. Please comment a little on vitamin C and longevity for our readers?


Sardi: Now that infant mortality rates are much lower than in past generations, efforts are being made to extend life by addressing age-related disease. The free-radical or antioxidant theory of aging is being investigated. You have been a disciple of Denham Harman, the originator of this theory, and most of your readers are well aware of the free radical theory of aging. But, for new readers, a brief overview is that free radicals can damage DNA which accelerates aging. This is fairly well established. Researchers are hinting at maximum levels of nutrient intake that will protect DNA rather than the current idea of an RDA that provides only minimal amounts to prevent overt deficiency diseases.

Your work normally involves combinations of antioxidants, but researchers have looked at the effect of vitamin C alone in extending human life? The Enstrom epidemiological study published in 1992 showed that just 300 mg of daily vitamin C from foods or supplements could expand the male lifespan by six years! [Epidemiology 3: 194-202, 1992] You interviewed Dr. Jim Enstrom of UCLA in this column shortly after the study was published.

The typical American diet only provides 110 mg of vitamin C, and five servings of fruits and vegetables, which are consumed by only 9% of the American population, would only provide about 210 mg of vitamin C. Widespread ascorbic acid supplementation would be needed for most adults to reach a 300-mg daily intake point. For comparison, cholesterol control and physical exercise only expand the human life span by 0.5 and 1.5 years respectively. There is so much emphasis on physical activity and cholesterol, but little emphasis to supplement with vitamin C.

It was Irwin Stone who made us aware that humans likely produced their own vitamin C at one time in the past. Animals that synthesize vitamin C live 8-12 times beyond their age of physical maturation. Humans physically mature at around age 18 and live only a little more than about four times longer. One can ponder if humans were still able to produce their own vitamin C, would they live considerably longer?


Passwater: We can also ponder what could come of the health of people if they learned of Drs. Hickey and Roberts claim that supplemental vitamin C taken in divided doses may vastly improve human health, and if there were a resurgence in vitamin C supplementation throughout the population, as there was when Dr. Linus Pauling wrote his books.


Sardi: If that were to happen, we could expect the incidence of cataracts to drop significantly, or at least to be delayed by quite a few years. [J Clinical Epidemiology 52: 1207-11, 1999] Arthritic symptoms would diminish in the population at large due to the maintenance of collagen. [Arthritis Rheumatism 39: 648-56, 1996] Rates of skin cancer might drop. The number of days in a year that people would be hampered with cold symptoms might be reduced, which would likely improve productivity in society overall. [Advances Therapy 19: 151-59, 2002] Viral eruptions such as herpes and SARS would be better controlled or even averted. [J Antimicrobial Chemotherapy 52: 1049-50, 2003] Smokers might live longer and not exhibit much of the pathology they develop. [J Am College Nutrition 22: 372-78, 2003] Rates of gallbladder disease would drop by about 25%. [J Clinical Epidemiology 51: 257-65, 1998] The incidence of aortic aneurysms (bulging and possible rupture) would be virtually eliminated. [Med Sci Monitor 10: 1-4,2004]

A study published in the March 2004 issue of the American Journal of Epidemiology indicates that males taking high-dose vitamin C exhibit 2.68 times less calcification in their arteries compared to males who consume low doses of vitamin C. The risk for angina among adults who consume significant amounts of alcohol would be cut in half. [Ann Epidemiology. 9: 358-65, 1999]

The Second National Health and Nutrition Examination Survey, published in the journal Epidemiology in March of 1998, found that adults who consume high amounts of vitamin C exhibit a 27% decreased prevalence of coronary heart disease and 26% decreased prevalence of stroke. In fact, for every 0.5 mg increase of vitamin C concentration per deciliter of blood serum there was an accompanying 11% reduction in coronary heart disease and stroke prevalence. Dr. Hickey says four divided 200-mg doses of ascorbic acid daily by a 160-pound healthy adult would likely achieve this 11% reduction in cardiovascular disease risk. A 500 mg dose taken four or five times a day might achieve a 55% reduction in cardiovascular disease risk!


Passwater: Unfortunately, people tend to listen more to the anti-vitamin “authorities” who speak out against vitamin C. Can you provide us with a briefing on recent attacks against high-dose vitamin C?


Sardi: A report from Duke University was the most recent vitamin C scare. The report warned consumers away from vitamin C supplements, stating: “Our findings suggest that dietary intake should not be supplemented above the currently recommended dietary allowance: 90 mg per day for men and 75 mg per day for women.” This was the advice of researcher Virginia B. Kraus, M.D., Ph.D., of Duke University Medical Center, and her colleagues.

Like other negative scientific reports about supplemental vitamin C in recent years, the study from Duke University Medical Center was released late on a Friday when criticism and rebuttal would be minimal. The report, published in the June issue of Arthritis & Rheumatism [June 2004; vol 50: pp 1822-1831], claims that high-dose vitamin C, when given to guinea pigs, worsens the occurrence of bone spurs in the knee joint.

But why did Duke University researchers warn the public away from supplemental vitamin C based upon a small animal study when a more comprehensive human study published in the same journal eight years earlier by researchers at the Arthritis Center, Boston University Medical Center, found that adults who consume high-dose vitamin C experience a threefold reduction in the risk for progression of their knee osteoarthritis, and that supplemental vitamin C reduces knee pain? [Arthritis Rheumatism 39, 648, 1996]

Two years ago another flawed report, published in Science Magazine, suggested high-dose vitamin C might damage DNA and warned the public to avoid high-dose vitamin C supplements. This study was also aired by the news media over a weekend, and the lead researcher was conveniently overseas and unavailable for questioning. The DNA test was conducted in a laboratory dish. But five human studies had already been published, which showed up to 10,000 mg of vitamin C taken orally by humans does not damage DNA. I wrote a letter to the editors of Science Magazine and wanted to know why their peer review had missed the earlier human studies. My letter challenging the flawed vitamin C/DNA damage claim was later published in Science. [Science. 293(5537):1993-5, Sept. 14, 2001]

In March of 2000, Dr. James Dwyer suggested at an American Heart Association meeting that high-dose vitamin C, 500 mg per day, actually thickens arteries and may worsen atherosclerosis. The thickening of the arteries was marginal as a physical measurement but the relative statistical increase was presented as a potential increase in risk for artery disease. Dr. Dwyers then unpublished report drew worldwide attention even though there were other contradictory studies that had been published. Vitamin C increases the production of collagen and the arterial thickening was evidence that vitamin C was doing its job—strengthening the walls of arteries.

Drs. Hickey and Roberts claim the NIH and IM have failed to investigate high-dose vitamin C for over 50 years. Drs. Hickey and Roberts arent alone in their claim that high-dose vitamin C may be beneficial. Dr. Carol Johnston, a vitamin C researcher at Arizona State University, has stated that very high intakes of vitamin C (2,000 to 4,000 mg per day) are well tolerated and that strong evidence to define and defend a safe upper limit for vitamin C is simply not available. [Nutrition Reviews 57: 71-77, 1999] If the public finds out about all this, there wont be enough vitamin C available.


Passwater: Well Bill, thanks for the call. Im sure our readers will appreciate the timeliness of this information. I guess we both have more work to do before we can go to our holiday picnics. WF


© 2004 Whole Foods Magazine and Richard A. Passwater, Ph.D.

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