Vitamin C

Water-soluble · ascorbic acid

What does Vitamin C do in your body?

Needed to make collagen, acts as an antioxidant, and boosts absorption of plant iron.

How it works, step by step

1. Absorbed in the small intestine by active transport.
2. Carried in blood to tissues.
3. Helps enzymes add hydroxyl groups to collagen strands.
4. Those groups let collagen form strong triple helices.

What does Vitamin C do?

A cofactor for enzymes that build collagen, carnitine and some neurotransmitters. Antioxidant in watery parts of cells.

Where does Vitamin C act in the body?

Skin, tendons, blood vessels, gums, immune cells, and the gut (iron absorption).

Which foods contain Vitamin C?

Citrus, kiwi, strawberries, bell peppers, broccoli, tomatoes, potatoes. Heat and long storage reduce it.

How much Vitamin C do adults need?

RDA: 90 mg (men), 75 mg (women); smokers add 35 mg. Upper limit: 2,000 mg/day.

What happens with too little Vitamin C?

Severe deficiency causes scurvy — bleeding gums, poor wound healing and fatigue — after about a month of very low intake.

Can you get too much Vitamin C?

Large supplement doses can cause diarrhea and stomach cramps, and may raise kidney stone risk in some people.

What does Vitamin C interact with?

Increases non-heme iron absorption when eaten in the same meal.

What is known and unknown about Vitamin C?

Regular supplements don't prevent colds in the general population but may slightly shorten them.

Evidence & sources

• The adult RDA for vitamin C is 90 mg (men) and 75 mg (women); smokers need 35 mg more. Evidence: regulatory. Known: Set by the Institute of Medicine (2000). Unknown: Benefits well above the RDA are not established. Source: NIH Office of Dietary Supplements, Vitamin C — Health Professional Fact Sheet (Current revision).
• Regular vitamin C supplements don't reduce how often most people catch colds. Evidence: strong. Known: Cochrane review of 29 trials; modest reduction in duration. Unknown: Benefit may differ in people under heavy physical stress. Source: Cochrane, Vitamin C for preventing and treating the common cold (2013).

Connected topics

• Iron
• Spinach
• Skin
• Tendons & Ligaments
• Immune & Lymphatic
• Orange

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General education only, not medical advice. Drafted Oct 2026 · pending qualified expert review.