Relation between plasma ascorbic acid and mortality in men and women in EPIC-Norfolk prospective study: a prospective population study

Background Ascorbic acid (vitamin C) might be protective for several chroni c diseases. However. findings from prospective studies that relate ascorbic acid to cardiovascular disease or cancer are not consistent. We aimed to a ssess the relation between plasma ascorbic acid and subsequent mortality du e to all causes, cardiovascular disease, ischaemic heart disease, and cance r. Methods We prospectively examined for 4 years the relation between plasma a scorbic acid concentrations and mortality due to all causes, and to cardiov ascular disease, ischaemic heart disease, and cancer in 19 496 men and wome n aged 45-79 years. We recruited individuals by post using age-sex register s of general practices. Participants completed a health and lifestyle quest ionnaire and were examined at a clinic visit. They were followed-up for cau ses of death for about 4 years. Individuals were divided into sex-specific quintiles of plasma ascorbic acid. We used the Cox proportional hazard mode l to determine the effect of ascorbic acid and other risk factors on mortal ity. Findings Plasma ascorbic acid concentration was inversely related to mortal ity from all-causes, and from cardiovascular disease, and ischaemic heart d isease in men and women. Risk of mortality in the top ascorbic acid quintil e was about half the risk in the lowest quintile (p<0.0001). The relation w ith mortality was continuous through the whole distribution of ascorbic aci d concentrations. 20 <mu>mol/L rise in plasma ascorbic acid concentration, equivalent to about 50 g per day increase in fruit and vegetable intake, wa s associated with about a 20% reduction in risk of all-cause mortality (p<0 .0001), independent of age, systolic blood pressure, blood cholesterol, cig arette smoking habit, diabetes, and supplement use. Ascorbic acid was inver sely related to cancer mortality in men but not women. Interpretation Small increases in fruit and vegetable intake of about one s erving daily has encouraging prospects for possible prevention of disease.