ALPHA-TOCOPHEROL CONCENTRATIONS IN PLASMA BUT NOT IN LIPOPROTEINS FLUCTUATE DURING THE MENSTRUAL-CYCLE IN HEALTHY PREMENOPAUSAL WOMEN

Because premenopausal women experience cyclic fluctuations of plasma c arotenoids and their lipoprotein carriers, it was hypothesized that pl asma alpha-tocopherol (A-T) fluctuates by phase of the menstrual cycle . Twelve free-living women, with a confirmed ovulatory cycle, were giv en a controlled diet for two consecutive menstrual cycles. Blood was d rawn during the menses, early follicular, late follicular and luteal p hases to simultaneously measure serum hormones, plasma lipoproteins an d A-T concentrations, and A-T distribution in the lipoprotein fraction s. Plasma A-T concentrations were significantly lower during menses th an during the luteal phase by similar to 12% in each controlled diet c ycle (P < 0.001). Adjustment for serum cholesterol and triglyceride co ncentrations did not alter these findings. The distributions of A-T in lipoprotein cholesterol fractions were not significantly different by menstrual phase. From 61 to 62% of A-T was concentrated in the LDL fr action, with another 9-14% in HDL2, 17-22% in HDL3 and the remaining 6 -8% in VLDL+ IDL. There were no significant differences in lipoprotein cholesterol fractions by menstrual phase, except for a significant in crease (P = 0.03) in HDL2 cholesterol from the early follicular to the late follicular phase. Spearman rank correlations from data during th e second controlled diet month showed A-T in HDL2 in the late follicul ar phase was positively correlated with HDL cholesterol in the early f ollicular (r = 0.88), late follicular (r = 0.86) and luteal phases (r = 0.86) and with luteal apolipoprotein (ApoA-1) level (r = 0.90), and luteal HDL3 cholesterol (r = 0.83). A-T in HDL3 in the early follicula r phase was negatively correlated with HDL2 cholesterol (r = -0.96) an d ApoA-1 (r = -0.85), whereas luteal A-T in HDL3 was correlated with l uteal HDL3 cholesterol (r = -0.79). Late follicular A-T in VLDL was po sitively correlated with early follicular HDL3 cholesterol and late fo llicular HDL3 cholesterol (r = 0.83). Fluctuations of A-T concentratio ns by phase of the menstrual cycle should be taken into consideration in future research concerning premenopausal women and the risk of chro nic disease.