What it does and colds
Vitamin C is essential for making collagen in skin, blood vessels, and gums; a deficiency causes scurvy, with bleeding gums and poor wound healing. It boosts absorption of plant iron, helping prevent anemia. A Cochrane review found that taking it daily doesn't prevent colds in the general population and shortens them by about 8% in adults. In people under heavy physical stress, like marathon runners, it cut cold risk roughly in half.
Food sources and megadoses
Bell peppers, broccoli, kiwi, strawberries, and oranges are packed with it, so a few servings of produce cover your needs. Extra is excreted in urine, but doses over 2 grams a day can cause diarrhea and cramps and may raise kidney stone risk. Heat destroys it, so eat some produce raw or lightly cooked.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Should I take vitamin C when I feel a cold coming?
- Starting it after symptoms begin hasn't shown consistent benefit in trials.
- When's the best time to take it?
- With a meal helps iron absorption and is easier on the stomach.
Sources reviewed: 2026-10-26
References
- National Institutes of Health Office of Dietary Supplements. Vitamin C: Fact Sheet for Health Professionals.
- Hemilä, H., & Chalker, E. (2013). Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews, (1), CD000980.
- 한국영양학회. (2020). 2020 한국인 영양소 섭취기준. 보건복지부.