Adjunct Therapy

• Vitamin C has been used for many years as a supplement to traditional cancer treatment. According to the Mayo Clinic, there is no definitive evidence that vitamin C is a beneficial adjunct therapy. The Mayo says more well-designed studies must be conducted before suggesting vitamin C has any cancer related benefits.
  
  The ACS says clinical trials of high doses of vitamin C supplements have not shown this antioxidant to be of any benefit as a cancer treatment. The ACS says researchers suspect that levels that reach the body when taken orally simply are not high enough to kill cancer cells
  
  

Intravenous Vitamin C

• There have been assertions that the body has a different response to vitamin C when it is administered intravenously (through an IV) than when taken orally.
  
  The ACS says it's too early to state what if any impact IV vitamin C will have in cancer treatment until clinical trials have been completed.
  
  

Prevention

• The ACS says eating a diet rich in vitamin C that includes fruits and vegetables (such as citrus fruits, berries, tomatoes, broccoli and spinach) have been associated with a lower risk of certain cancers in population studies.
  
  It's unclear, however, if these benefits are due solely to the vitamin C contained in these foods.
  
  The ACS also points out that vitamin C supplements have not been connected with this possible protective effect against cancer.
  
  

Precautions

• The ACS says vitamin C supplements of up to 2,000 milligrams (2 grams) per day are generally considered to be safe.
  
  According to the ACS, most oncologists typically recommend that cancer patients refrain from taking gram-size doses of vitamin C during treatment.
  
  People who have cancer should consult with their doctor before taking vitamin C supplements.
  
  

Conclusion

• The ACS says numerous studies have indicated that you may lower your risk of getting cancer by eating a diet rich in foods that contain Vitamin C. However, there is no solid proof that the vitamin C contained in foods or in supplements are an effective cancer fighting treatment.
  
  The National Cancer Institute (NCI) says studies involving animals and cell cultures suggests antioxidants (including vitamins C, E, and A, and others) may slow or possibly prevent the development of cancer. However, more recent large-scale, clinical trials had conflicting findings.