Many people routinely take high doses of vitamin C and other antioxidants in the belief that they will prevent or cure illnesses. However, according to new research, cancer patients who take large doses of vitamin C in the hope of a cure might actually make their disease worse by inadvertently protecting their tumors from radiation and chemotherapy.
While there is no proof that the vitamin is harmful during cancer treatment, medical experts say there is strong biological reasons to think megadoses should be avoided.
The proper dosage of vitamin C in the diet has been a subject of much debate in the medical community. Researchers from the National Institutes of Health recommended raising the RDA for vitamin C from 60 mg to between 100 mg and 200 mg. At the same time, many health experts say doses greater than 200 mg are useless at best, and potentially harmful. Note, however, that the US Government comes up with recommended daily allowances (RDA) from the perspective of preventing deficiencies like scurvy, not as natural therapeutic agents.
In 1998, a widely publicized study in the journal Nature linked daily doses of 500 mg of vitamin C to DNA damage. The results and methodology of that study have since been criticized, but many medical experts remain skeptical about pumping up the intake of vitamin C.
The one thing that is clear is that diet, and especially the typical American diet, alone is usually not sufficient to supply the nutrients necessary for overall good health. While most experts agree that nutritional supplements are vital for a variety of illnesses and age-related problems, vitamin and mineral supplements can also help to maintain optimal physical and psychological health, promote longevity, and prevent chronic disease.
Even so, too much of anything – including vitamins and supplements – can be toxic. The key is moderation, and common sense. Anyone currently under medical care, taking prescription medications, or having a history of specific problems should always consult with a professional health care provider (one knowledgeable about diet and supplemental nutrients) before making any changes in diet or lifestyle.