Influence of combined antioxidant nutrient intakes on their plasma concentrations in an elderly population

Data from a cross-sectional survey of 746 non-institutionalized, Boston-area elderly individuals (aged > or = 60 y) were analyzed to assess the relation between antioxidant nutrient intake and plasma antioxidant status. Intakes of vitamin C and carotenoids and supplemental vitamin E were estimated by using 3-d diet records. Mean plasma concentrations of these nutrients were calculated within categories of intake, and polynomial contrasts were used to test for linear trends of the plasma nutrient concentrations across these categories. Adjustments for the corresponding intake of the plasma nutrient under consideration, as well as age, sex, and smoking status were made to minimize potential confounding. Plasma alpha-tocopherol concentrations were 18% greater in individuals consuming > or = 220 mg vitamin C/d compared with those with intakes < 120 mg/d (P for trend < 0.001). Plasma carotenoid concentrations were 13% higher across increasing categories of vitamin C intake (P for trend = 0.002). An increasing intake of carotenoids was moderately associated with higher plasma alpha-tocopherol (P for trend = 0.008) and unrelated to ascorbic acid status. An increasing intake of supplemental vitamin E was weakly correlated with plasma ascorbic acid (P for trend = 0.05) and unrelated to carotenoid status. These results provide epidemiologic evidence that increasing intake of either vitamin C, vitamin E, or carotenoids is associated with greater plasma concentrations of one or both of the other antioxidant vitamins and not associated with any impairment in antioxidant status.