Leucine Requirements During Different Phases of the Menstrual Cycle in Eumenorrheic Women

The objective of the study is to determine leucine requirements using the indicator amino acid oxidation method during the follicular phase and the luteal phase of the menstrual cycle in healthy women (between the ages of 20-35 y).In comprehending protein needs and achieving protein targets, it is imperative to establish individual amino acid requirements. This clinical study aims to determine the dietary requirements of leucine for women, helping build a strong foundation for setting dietary guidelines for women. The existing values, derived from guidelines designed for men, overlook the crucial impact of the menstrual cycle on energy and dietary intake. Relying on amino acid requirements derived from studies in men for women significantly heightens the risk of potential harm. It is crucial to identify the distinct amino acid requirements for women and grasp how these needs are affected by various phases of the menstrual cycle. A minimum of 15 healthy women (20-35 y) will be recruited and studied at two menstrual phases over a range of test leucine intakes (10, 20, 30, 40, 55, 70, and 85 mg/kg/day). Women will be invited to participate in up to 7 study days/phase, and randomized to a different intake at each study day. Participants' eligibility will be assessed during a pre-study day. The goal is to study a minimum of 7 women at each intake, for a total of 49 study days in each stage.