Vitamin C

Studies in people

• Benefit

  Immune system support²

  Vitamin C helps immune cells work and may help prevent and treat chest and other infections.

• Benefit

  Fatal vitamin deficiency disease³

  Vitamin C prevents scurvy, a disease that can be fatal if not treated with the vitamin.

• Benefit

  Common cold symptoms⁴

  Vitamin C may shorten bad cold symptoms more than mild ones, though scientists are still studying this.

• Open question

  Long-term health effects⁵

  Vitamin C may help prevent some diseases, but studies disagree and scientists do not yet know for sure.

• Open question

  Common cold severity⁶

  Vitamin C may shorten and ease colds, but studies in people show mixed results.

• Benefit

  Stress hormone levels⁷

  In women with high stress hormones, vitamin C supplements lowered their cortisol and DHEA-S levels.

• Benefit

  Antioxidant levels in women⁸

  In postmenopausal women with insulin resistance, vitamin C raised total antioxidant capacity, though it did not change insulin resistance.

• Open question

  Heart and cancer risk⁹

  Whether vitamin C in fruits and vegetables protects against heart disease and cancer is not yet known.

• Benefit

  Pelvic pain in endometriosis¹⁰

  In women with endometriosis, vitamin C plus vitamin E eased pelvic pain, period pain and pain during sex.

• No harm found

  Colds and infections¹¹

  Vitamin C supplements do not appear to prevent colds or pneumonia in most well-fed people.

• Benefit

  Iron absorption from food¹²

  Vitamin C helps the body take in iron from vegetables and can cancel out tea's blocking effect.

• Open question

  Blood pressure in the lungs¹³

  A man with very low vitamin C got high blood pressure in his lungs, which eased after vitamin C supplements.

• Benefit

  Cholesterol levels in the elderly¹⁵

  In older people, eating more vitamin C was linked to better cholesterol and blood fat levels.

• Benefit

  Placenta blood flow in pregnancy¹⁶

  In pregnant smokers, vitamin C improved blood flow in the cord, reaching levels like nonsmokers.

• Benefit

  Mouth cancer risk¹⁷

  In adults in Southern China, higher vitamin C intake was linked to lower oral cancer risk.

• Benefit

  Diabetes in pregnancy¹⁸

  In women, vitamin C supplements seemed to offset the higher diabetes-in-pregnancy risk linked to mercury and arsenic.

• Benefit

  Gout risk²⁰

  People who ate more vitamin C in food were less likely to have gout, but vitamin C pills showed no link.

• Benefit

  Frailty risk in women²¹

  In Korean women, more fruits and vegetables and their vitamin C were linked to less frailty; vitamin C pills were not.

• Benefit

  Gout risk in adults²³

  In US adults, eating more vitamin C was linked to lower odds of high uric acid.

Study type not stated

• Benefit

  Brain and memory health²⁵

  Vitamin C, taken with zinc, may help prevent dementia, but how sure this is isn't stated.

How it’s made and used

• Bleeding gums and limb pain¹⁴

  Children with too little vitamin C in their diets often had limb pain, refused to walk, and had bleeding gums.

• Diet-related vitamin deficiency¹⁹

  People with hereditary fructose intolerance eating a restricted diet often had low vitamin C, and supplements helped.

• Daily requirement factors²²

  Vitamin C needs differ by age, sex, pregnancy and smoking, with smokers needing more than non-smokers.

• How much is too much²⁴

  Vitamin C has a recommended daily amount, and experts set a level for how much is too much.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least one finding in people. When most findings in people point one way, the page leans that way (“Mostly”), and every finding is still shown. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.