Reference values for plasma concentrations of vitamin E and A and carotenoids in a swiss population from infancy to adulthood, adjusted for seasonal influences

Abstract

In a cross-sectional survey, plasma concentrations of α-and γ- tocopherol α- and β-carotene (cis and trans isomers), lycopene, and retinol were determined by reversed-phase HPLC, and ratios of plasma α-tocopherol to cholesterol were calculated in 208 Swiss individuals ages 0.4-38.7 years. The influence of age, sex, and season of sampling was studied. Age was a significant predictor of all plasma concentrations except α-carotene. No sex-related differences were observed. Season of sampling affected α- tocopherol and retinol (higher in winter) and γ-tocopherol and cholesterol concentrations (higher in winter and spring than in the other seasons). After correction for seasonal influences, age differences were 0.24 μmol/L per year for α-tocopherol, 0.04 μmol/L per year for retinol, and 0.04 μmol/L per year for cholesterol concentrations; ratios of plasma α-tocopherol to cholesterol were not affected by age. We constructed age-specific reference intervals from the regression line and a multiple of the standard deviation. Separate regression equations are presented for seasons with low and high values.