Biological variability in serum vitamin E concentrations: relation to serum lipids

The components of biological variation in serum vitamin E in relation to serum cholesterol, triglycerides, high- and low-density lipoprotein cholesterol (HDL-C, LDL-C), apolipoprotein A-I (apo A-I), and apo B were examined in 26 healthy volunteers who had monthly blood samplings during one calendar year. The estimated CVs for vitamin E were: interindividual, 19.9%, and intraindividual, 11.9%; the index of individuality (I-index) was 0.59. The I-indices for all lipid variables were < 0.51. Serum concentrations of vitamin E, cholesterol, triglycerides, HDL-C, LDL-C, and apo B were lower in spring than in the other seasons. The peak-trough differences in the yearly variations, expressed as a percentage of the mean, were for vitamin E 14.5%, cholesterol 16.2%, triglycerides 14.5%, and LDL-C 24.3%. A significant common annual rhythm was expressed in vitamin E or lipid variables and in the changes in ambient temperature the weeks before blood sampling (inverse relations). There were highly significant positive time relations between serum vitamin E and cholesterol, triglycerides, and apo B. Subjects with higher homeostatic setpoints of cholesterol showed higher homeostatic setpoints of vitamin E, triglycerides, LDL-C, and apo B.