http://www.mercola.com/2001/jun/23/vitamin_c.htm

 

Does Vitamin C Really Damage Your DNA?

Vitamin C is an essential protector of body cells.

A newly published study says the vitamin can also play a "dual role" and, at times, actually damages cells' genetic material. Investigators say their findings could help explain why high-dose vitamin C has so far failed as an experimental cancer therapy.

The study showed that rancid fat molecules can react with vitamin C to form products that could potentially harm DNA, although the reaction of these products with DNA was not demonstrated in the study.

Hence, it was suggested that vitamin C can form genotoxins (DNA-damaging agents) from lipid hydroperoxides, the implication being that vitamin C may enhance mutagenesis and the risk of cancer.

Previous research has shown vitamin C can promote DNA damage, but this new research demonstrates a different avenue the vitamin can take in doing harm.
In the average person, vitamin C may regularly act as both a cell's friend and foe, making a daily megadose of vitamin C unlikely to fight illness.

This is a test tube experiment and here is "little evidence" that these harmful effects of vitamin C are actually going on in the body.

What's more, a significant number of studies have shown vitamin C to either have no effect or a positive impact on DNA.

As an antioxidant, vitamin C helps neutralize cell-damaging free radicals, which are byproducts of metabolism found throughout the body. Because of this activity, some scientists have suggested that high doses of vitamin C might help battle cancer by both protecting healthy cells from the assaults of cancer treatment and by fighting tumor cells.

The free radicals that vitamin C normally combats can damage DNA directly or by converting certain fatty acids into genotoxins. The researchers found that in the test tube, vitamin C can also give rise to genotoxins by oxidizing these fats.

According to the researchers, these findings suggest it will be particularly important to be on guard for cell damage among participants in trials using vitamin C as a cancer combatant.

For healthy people the message echoes tried-and-true nutrition advice: eat a balanced diet rich in fruits and vegetables rather than popping a high-dose vitamin C pill, since the vitamin is no "magic bullet."

The popularity among health-conscious Americans for popping vitamin C pills was boosted by Linus Pauling, a Nobel-prize-winning chemist who advocated large doses of the vitamin. He routinely took 15 grams daily and was 93 years old when he died in 1994.

However, a nutrient expert at the institution named for Pauling, said such large doses of vitamin C have not been proven to be beneficial in clinical studies. The Linus Pauling Institute does not currently endorse megadoses or promote vitamin C in preventing a cold.

They also only recommend taking 200 mg of vitamin C as a healthy body can only absorb about that much a day and the surplus is carried away with the urine.Their advice is to eat a healthy diet rich in fruits and vegetables.

The Institute of Medicine, an arm of the National Academy of Sciences, recommends that women need 75 milligrams of vitamin C daily and 90 milligrams for men. Smokers need an additional 35 milligrams. These are levels easily achieved by a balanced diet.

Science June 15, 2001;292:2083-2086 and Washington Post June 14, 2001

DR. MERCOLA'S COMMENT:

The media has attempted to place a negative spin on vitamin C. If you want to understand why this is, please review the excellent article I posted last year.

There are many reasons why this study is not supportive of the fear being suggested that vitamin C will cause cancer. They will be reviewed further down in this response.

However, recent studies show that Americans only consume about 100 milligrams of vitamin C from foods and that about 5% of Americans consume so little vitamin C that they exhibit signs of scurvy.

So some of us need to increase our vitamin C intake. The solution is to obviously increase your vegetables and fruits. If for some reason you can't do that, then you should consider a vitamin C supplement that is balanced with bioflavanoids.

However, always remember, that whole foods are nearly always a better choice than supplements.

It is interesting to note that the Linus Pauling Institute does not promote megavitamin therapy for healthy adults and they are in agreement with lower doses as mentioned in the story above.

There are conditions, such as high levels of a certain substance called Lp(a) in which megadoses of vitamin C may be useful.

They also posted a report on this study which does a wonderful job of breaking it down and providing you with the truth behind the headlines.

To learn more, try the Linus Pauling Institute's Vitamin C information page.

COMMENT FROM LINUS PAULING INSTITUTE:

Let us remember that this study is a test tube experiment. The study does not describe biochemistry or biology, and its relevance to reactions occurring in cells and tissues of the human body is unknown. Many reactions of vitamin C occur in vitro (in the test tube) that will not and cannot occur in vivo (in the living organism).

Why?

Because the physiological environment of the cell and the body contains thousands of substances that also react with vitamin C and rancid fats thus derailing the chemistry observed in a test tube system.

Rancid fats don't just wait around in vivo to bump into a vitamin C molecule, but instead are very rapidly reduced to harmless "alcohols" by a number of enzymes.

Thus, the reaction rate of rancid fats with these enzymes compared to the reaction rate of the rancid fats with vitamin C is of crucial importance and this was not measured in the Science study.

From what we know from the study, incubations were done for two hours, an eternity in biochemical terms. Enzymatic reactions as those indicated above to reduce rancid fats to harmless alcohols that do not react with vitamin C usually take a fraction of a second, not two hours!

It is interesting to note that vitamin C effectively inhibits the formation of rancid fats in the first place. Thus, when your blood is exposed to oxidizing conditions, vitamin C forms the first line of antioxidant defense, and no lipid rancid fats are formed.

Rancid fats begin to form only after vitamin C has been exhausted. Thus, in these experiments rancid fats and vitamin C did not exist simultaneously in blood, and thus never had the opportunity to react with each other.

What's more, the Science study used a concentration of rancid fats which in biochemical terms was "a ton." Studies have shown that, in blood, rancid fats exist in concentrations which are 10,000-fold lower than what was used in the Science experiment. Again, this casts serious doubt on the relevance of these results for living organisms.

To conclude from this study that vitamin C causes cancer would be as preposterous as to say that we have found a cure for cancer based on a simple test tube experiment.

In fact, many animal studies and cell culture experiments have demonstrated anticancer effects of vitamin C, and the vitamin has been used therapeutically in human cancer patients with some apparent benefit.

Abstracted from Linus Pauling Institute Release

Related Articles:

Does Vitamin C Cause or Prevent Cancer?

Linus Pauling's Unified Theory and Therapy for Heart Disease

Vitamin C Foundation Rebuttal to Science Study

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