All About Antioxidants and Vitamins -

Possible Dangers Of Vitamin C

Vitamin C has an excellent safety record and has been taken in 1,000 mg ( 1 gram ) plus doses by millions of people with no apparent disadvantage. To balance this there has been a handful of reports of ill effects of very large doses thought to be due to the vitamin. One of these was published in the British Medical Journal in March 1993. This paper reports the case of a 32 year old HIV positive man who developed generalized lymph node enlargement. He was advised by his doctors to start AZT treatment but refused and sought the advice of a medically qualified nutritionist. Investigation showed that he had a lower than normal blood level of the antioxidant, glutathione, and he was prescribed, among other things, glutathione supplements and a course of vitamin C to be given in a dosage of 40,000 mg ( 40 grams) by intravenous injection, three times a week, plus 20,000 to 40,000 mg ( 20 to 40 grams ) every day by mouth. This enormous dosage was continued for a month with no obvious change in his condition. the intravenous dose was then doubled to 80,000 mg ( 80 grams). The next day he became breathless and feverish and his urine turned to a black color, indicating that many red blood cells had broken down, releasing hemoglobin which was passing out in the urine, much in the manner of malarial 'black water fever'.

Investigation showed that this man had sickle cell trait and a comparatively rare genetic blood disorder known as 'glucose 6 phosphate dehydrogenate deficiency'. This enzyme deficiency disorder makes red blood cells much more fragile than normal because of a shortage of the antioxidant, glutathione, which protects the red cells against free radical damage. Many drugs in common use can cause the red cells to break down in this condition. the patient was given lots of fluid to drink so as to flush through his kidneys, and on the third day the urine was clear. He made a complete recovery from the red blood cell breakdown.

Dosages of this order are ridiculously high and there are very few remedies that can, with perfect safety, be taken in quantities of 20 or 30 times the customary dosage. This patient was receiving dosages of about 500 times the recommended daily allowance. The report does, however, indicate that there are some people who ought to be particularly cautious about taking any drug, even one as apparently safe as vitamin C.

In April 1998 a research report appeared in the journal Nature. This was an account of a study at the University of Leicester by a team headed by Dr. Ian Pod more. DNA contains four bases guanine, adenine, thymine and cytosine and it is the order of these along the DNA chain that is the genetic and adenine that had been damaged by oxidation. Thirty healthy volunteers were given 500 mg of vitamin C every day and the levels of oxidized guanine and adenine were measured. As might be expected, the levels of oxidized guanine did fall.

The important point, however, is that those of oxidized adenine actually rose. After stopping the vitamin dosage the levels of both of these markers of oxidation fell back to normal within seven weeks. DNA is being attacked all the time by free radicals and is constantly being repaired. Evidence that vitamin C can apparently increase oxidative damage to one of the four bases of DNA is puzzling. Should we conclude from this that vitamin C can be harmful? At this stage we cannot answer this question. The best we can do is to try to balance this finding against the mass of epidemiological and other evidence supporting the beneficial effects of vitamin C. Then we must make up our own minds.