Reference Values for α-Tocopherol and β-Carotene in the Whitehall II Study

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Abstract
Plasma α-tocopherol, β-carotene, serum lipids and their derived ratios were determined in British Civil Servants (n = 7177) at the second medical examination of the Whitehall II Study, a longitudinal study of cardiovascular disease. For plasma α-tocopherol the non-parametric 95% reference interval (90% confidence limits) for the total population was: 11.1 (10.9–11.3) -51.5 (50.6–52.7) μmol/1. For plasma p-carotene the nonparametric reference interval for the total population was: 0.05 (0.05–0.05) - 2.14 (2.08–2.21) μmol/1. The latter interval was wider than those previously published with a higher mean (0.61 μmol/1) and median (0.75 μmol/1). Plasma β-carotene concentrations were higher in women than men with age-adjusted means of 0.70 and 0.57 μmol/1 respectively (p i 0.001). This may reflect differences in diet, lifestyle and metabolism between the sexes. The a-tocopherol/cholesterol ratio, as in other surveys, did not vary with age. Among men, current- and ex-smokers had a higher α-tocopheroll cholesterol ratio than never-smokers with age-adjusted means of 4.18, 4.19 μmol/mmol and 4.05 μmol/mmol respectively. This difference is as yet unexplained. Follow-up of these subjects will help to clarify the role of antioxidant nutrients as protective factors for cardiovascular disease and cancer.