Intervention
The intervention was the administration of γ-Toc and a placebo. γ-Toc and placebo were manufactured as capsules and supplied by Eisai Food Chemical (Tokyo, Japan). Each γ-Toc capsule contained 92 mg γ-Toc, 1.7 mg α-Toc, 1.7 mg β-Toc, and 1.0 mg δ-Toc, which was dissolved in vitamin E- stripped corn oil. The placebo capsules only contained vitamin E-stripped corn oil and had the same appearance, size, and color as the γ-Toc capsules. Participants were required to take both test supplements in a crossover fashion, each for 7 days during the luteal phase of one menstrual cycle. Two capsules were taken twice a day, after breakfast and evening meals.