Some in vitro (test tube) and in vivo studies have reported that vitamin C is a potent anticancer agent, which enhances the cytotoxic action against cancer cells by promoting the activity of the immune system, creating a destructive barrier for cancer progression, including metastasis.
Vitamin C is a potent antioxidant that may help scavenge reactive oxygen species, preventing DNA damage and other effects important in cancer transformation.
What is Vitamin C?
Vitamin C (ascorbic acid, ascorbate) is an essential micronutrient, which belongs to the water-soluble group of vitamins and is delivered either through diet or as a supplement.
Vitamin C is an antioxidant that protects cells and tissues from free radical damage and synthesizes important substances, such as collagen protein, in the body.
Vitamin C deficiency can lead to scurvy, a disease characterized by gum bleeding, loss of teeth, and increased skin bruising.
Some conditions that may increase the risk of vitamin C deficiency include:
- Low dietary consumption of vegetables and fruits
- Excessive alcohol consumption
- Active or passive smoking
- Food allergy and dietary restrictions
- Drug or substance abuse
- Inflammatory bowel disease
- Tobacco chewing
- Chronic kidney disease
- Eating disorders
What Are the Nutritional Requirements of Vitamin C Each Day?
| Age group | Gender | Recommended daily intake | Pregnancy | Breastfeeding |
|---|---|---|---|---|
| 0 to 6 months | Males | 40 mg | ||
| Females | 40 mg | |||
| 7 to 12 months | Males | 50 mg | ||
| Females | 50 mg | |||
| 1 to 3 years | Males | 15 mg | ||
| Females | 15 mg | |||
| 4 to 8 years | Males | 25 mg | ||
| Females | 25 mg | |||
| 9 to 13 years | Males | 45 mg | ||
| Females | 45 mg | |||
| 14 to 18 years | Males | 75 mg | ||
| Females | 65 mg | 80 mg | 115 mg | |
| 19 years and older | Males | 90 mg | ||
| Females | 75 mg | 85 mg | 120 mg | |
| Smokers | Males | Recommended daily amount + 35 mg | ||
| Females | Recommended daily amount + 35 mg |
What Are the Dietary Sources of Vitamin C?
Certain fruits and vegetables that have a good amount of vitamin C include:
- Citrus fruits (such as oranges, grapefruits, and limes)
- Peppers (red and green)
- Kiwi
- Watermelon
- Papaya
- Tomatoes
- Pineapple
- Berries
- Leafy greens
- Broccoli
- Cantaloupe
- Brussels sprout
- Potatoes
Are There Any Side Effects of Taking Excess Vitamin C?
Excessive vitamin C intake can lead to some side effects, such as:
It is recommended that vitamin C supplements should be used with caution in people who:
- Are on certain medications, such as:
- Niacin and statins (for lowering cholesterol levels).
- Those used to treat Alzheimer’s disease.
- Are receiving cancer treatment (chemotherapy and radiation therapy).
- Have hemochromatosis.
What Are the Other Functions of Vitamin C?
Vitamin C plays a key role in various functions of the body, such as:
- Promoting healthy and strong bones, cartilage, teeth, and gums
- Improving immune system function
- Protecting body cells against the damaging effects of free radicals
- Promoting wound healing by producing collagen
- Helping in iron absorption from the gut
- Enhancing the production of neurotransmitters in the brain and nerves
- Promoting the adrenal glands to produce crucial hormones
- Reducing the effects of skin aging
- Maintaining the health of the heart and blood vessels
- Improving brain health
- Maintaining eye health
From 
Pro- and Antioxidant Effects of Vitamin C in Cancer in correspondence to Its Dietary and Pharmacological Concentrations NIH https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6942884/#:~:text=Vitamin%20C%20was%20shown%20to,in%20CRC%20cells%20%5B107%5D.
Intravenous High-Dose Vitamin C in Cancer Therapy National Cancer Institute https://www.cancer.gov/research/key-initiatives/ras/ras-central/blog/2020/yun-cantley-vitamin-c
Therapeutic Use of Vitamin C in Cancer: Physiological Considerations Frontiers https://www.frontiersin.org/articles/10.3389/fphar.2020.00211/full
Is it possible to take too much vitamin C? Mayo Clinic https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/vitamin-c/faq-20058030