Vitamin C and colds

Answer 1

Alternative Names

Colds and vitamin C

Information

Despite the popular belief that vitamin C can cure the common cold, the scientific evidence for this is conflicting.

Large doses of vitamin C may help reduce the duration of a cold, but they do not appear to protect against one in the first place, even after exposure to a cold virus.

Vitamin C may only be useful in case of a cold if you have low levels of this nutrient to begin with. For example, the vitamin may be useful for preventing a cold if you live in very low temperature environments, or you are routinely involved in vigorous exercise such as marathon running.

The likelihood of success may be very individual -- some people improve, while others do not.

People with kidney disease should avoid vitamin C supplements. Most experts advise that you meet your daily vitamin and mineral requirements by eating a balanced diet. Taking more than 500 mg of vitamin C at any one time provides no advantage. More than that amount is simply lost through nonabsorption or urination.

References

Douglas RM, Hemila H, Chalker E, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD000980.

Simasek M, Blandino DA. Treatment of the common cold. Am Fam Physician. 2007;75:515-520.

Answer 2

Alternative Names

Colds and vitamin C

Information

Despite the popular belief that vitamin C can cure the common cold, the scientific evidence for this is conflicting.

Large doses of vitamin C may help reduce the duration of a cold, but they do not appear to protect against one in the first place, even after exposure to a cold virus.

Vitamin C may only be useful in case of a cold if you have low levels of this nutrient to begin with. For example, the vitamin may be useful for preventing a cold if you live in very low temperature environments, or you are routinely involved in vigorous exercise such as marathon running.

The likelihood of success may be very individual -- some people improve, while others do not.

People with kidney disease should avoid vitamin C supplements. Most experts advise that you meet your daily vitamin and mineral requirements by eating a balanced diet. Taking more than 500 mg of vitamin C at any one time provides no advantage. More than that amount is simply lost through nonabsorption or urination.

References

Douglas RM, Hemila H, Chalker E, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD000980.

Simasek M, Blandino DA. Treatment of the common cold. Am Fam Physician. 2007;75:515-520.

Reviewed By

Review Date: 05/13/2010

Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.