High doses of vitamin C (ascorbic acid) have been recommended as a treatment for a variety of cancers, including breast cancer. Vitamin C is a micronutrient that is essential to human health. High-dose vitamin C supplementation may reduce the risk of childhood leukemia, as well as cancers of the mouth, skin, stomach, pancreas, colon, endometrium and prostate. Some breast cancer patients have low blood concentrations of antioxidants compared to healthy women. This may suggest that patients have exhausted the body’s antioxidant defense system and are susceptible to oxidative damage, potentially further promoting breast cancer. Laboratory studies have found that different concentrations of vitamin C inhibit the growth of human breast cancer cells. However, there are no academic studies to confirm a survival benefit of high doses of vitamin C in women. Current evidence suggests that vitamin C contained in a normal diet has a preventive effect on breast cancer. High doses of vitamin C may be detrimental to breast cancer patients. While vitamin C has synergistic effects with other cancer-fighting foods, high doses of vitamin C may diminish the preventive effect of micronutrients against breast cancer. Food sources of vitamin C The following foods are rich in vitamin C and have preventive effects against breast cancer: bell peppers, broccoli, Brussels sprouts, cabbage, cauliflower, kale, peppers, collard greens, lettuce, mustard greens, oranges, celery, raspberries, tomatoes, watermelon. Conclusion: Most breast cancer patients and those at high risk can get vitamin C through their diet. vitamin C supplementation is not necessary, and treating high doses of vitamin C intake may be counterproductive. Vitamin C supplements should not be taken during chemotherapy.