Serum concentrations of retinol (A), ascorbic acid (B), α-tocopherol (C), lutein (D), lycopene (E), and β-carotene (F) in 259 healthy premenopausal women in the BioCycle Study across phases of the menstrual cycle for up to 2 cycles (509 cycles). Values are means and 95% CIs. Means without a common letter differ, P < 0.05 (adjusted for multiple comparisons). Sample sizes represent number of cycles (up to 2 per woman) for each cycle phase (all models take multiple visits per cycle and multiple cycles per woman into account). F, follicular phase; L1–L3, luteal phase; M, menses; O1–O3, ovulatory phase.