Plasma ascorbate in a population of children: influence of age, gender, vitamin C intake, BMI and smoke exposure.

The objective of this study is to determine the influence of several personal and lifestyle factors on the levels of circulating vitamin C in a population of children. To accomplish this objective, blood samples were collected from 511 healthy children residing in the Greater San Juan area. The population was stratified into 4 percentile groups (approaching quartiles) according to plasma ascorbate levels from lowest to highest concentrations. Comparisons were made between percentile groups on the basis of age, gender, body mass index (BMI), dietary intake of vitamin C (corrected and uncorrected for energy intake) and exposure to environmental tobacco smoke (ETS). Smoke exposure was determined using urinary cotinine, which is a highly sensitive bioindicator for ETS. Dietary vitamin C was determined via one 24hr recall questionnaire. When all 4 percentile groups were used as a basis of comparison, no differences were noted for any of the factors between groups, however when comparing percentile group 1 (lowest blood ascorbate) to an aggregate value of percentile, groups 2-4, it was found that vitamin C intake (corrected for energy intake) paralleled blood values with a statistically significant association. Among personal and environmental factors only exposure to ETS showed a significant difference in blood levels between groups 2-4 and group 1. No differences between percentile groups were noted for age gender or BMI. These results emphasize that ETS is strongly associated with lowered blood ascorbate levels with the obvious implication of reduced antioxidant protection and increased risk of adverse health consequences.