Vitamin C in doses as high as one gram daily for several winter months , had no consistent beneficial effect on incidence of the common cold .
For both preventive and therapeutic trials , there was a consistently beneficial but generally modest therapeutic effect on duration of cold symptoms .
There was no clear indication of the relative benefits of different regimes or vitamin C doses .
However in trials that tested vitamin C after cold symptoms occurred , there was some evidence that a large dose produced greater benefits than lower doses .
REVIEW ER 'S CONCLUSIONS Long term daily supplementation with vitamin C in large doses daily does not appear to prevent colds .
BACKGROUND The role of oral ascorbic acid ( vitamin C ) in the prevention and treatment of colds remains controversial despite many controlled trials .
There have also been a number of efforts to synthesize and /or overview the results of these trials , and controversy over what these overviews tell us .
OBJECTIVES The objective of this review was to answer the following two questions : ( 1 ) Does regular high dosage supplementation with vitamin C reduce the incidence of colds ? (
2 ) Does taking vitamin C in high doses at the onset of a cold have a therapeutic effect ?
Evaluation of the efficacy of ascorbic acid in prophylaxis of induced rhinovirus 44 infection in man.
Twenty-one healthy , susceptible adult male volunteers were enrolled in a doubleblind study design ed for evaluation of the prophylactic efficacy of ascorbic acid ( 3 g daily ) in induced rhinovirus 44 infection of the upper respiratory tract . While in continuous isolation , 11 men received 1 g of ascorbic acid three times daily , and 10 men received a placebo for two weeks , after which an intranasal inoculum containing 100 TCID50 of rhinovirus 44 was administered . Each man continued to receive the same dose of medication for one week after the viral challenge . All participants subsequently developed typical illness due to rhinovirus . Similar levels of antibody in serum , nasal washings , and sputum developed in all subjects . Nasal shedding of virus and the flow of the nasal mucociliary blanket were unaffected by the ingestion of ascorbic acid . No prophylactic benefit was demonstrated from the daily ingestion of 3 g of ascorbic acid in induced rhinovirus 44 infection in man . Viral infections of the respiratory tract are the most common illness affecting mankind . The mortality from these afflictions is low , but the morbidity , when assessed as discomfort and time lost from gainful employment and leisure pursuits , is high . Therefore , it is critical to assess the controversial cl aims for the efficacy of ascorbic acid ( vitamin C ) for the prevention and relief of colds [ 1 - 5 ] . The need for a further study of the possible role of ascorbic acid in the prophylaxis and therapy of viral infections of the respiratory tract under carefully controlled circumstances was evident
Vitamin C in doses as high as one gram daily for several winter months , had no consistent beneficial effect on incidence of the common cold .
For both preventive and therapeutic trials , there was a consistently beneficial but generally modest therapeutic effect on duration of cold symptoms .
There was no clear indication of the relative benefits of different regimes or vitamin C doses .
However in trials that tested vitamin C after cold symptoms occurred , there was some evidence that a large dose produced greater benefits than lower doses .
REVIEW ER 'S CONCLUSIONS Long term daily supplementation with vitamin C in large doses daily does not appear to prevent colds .
BACKGROUND The role of oral ascorbic acid ( vitamin C ) in the prevention and treatment of colds remains controversial despite many controlled trials .
There have also been a number of efforts to synthesize and /or overview the results of these trials , and controversy over what these overviews tell us .
OBJECTIVES The objective of this review was to answer the following two questions : ( 1 ) Does regular high dosage supplementation with vitamin C reduce the incidence of colds ? (
2 ) Does taking vitamin C in high doses at the onset of a cold have a therapeutic effect ?