Phenylalanine needs during the follicular and luteal menstrual phases

Phenylalanine Requirements in the Menstrual Phases

Not applicable Interventional University of British Columbia · NCT07481201

We will test how much phenylalanine healthy menstruating women (ages 20–35) need during the follicular versus luteal phase of the menstrual cycle.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment15 (estimated)
Ages20 Years to 35 Years
SexFemale
SponsorUniversity of British Columbia Academic / other
Locations1 site (Vancouver, British Columbia)
Trial IDNCT07481201 on ClinicalTrials.gov

What this trial studies

This interventional study uses the minimally invasive indicator amino acid oxidation method with safe stable isotopes, controlled diets, and simple breath collections to estimate dietary phenylalanine requirements in healthy menstruating females. Participants (minimum 15) will be studied in both the follicular and luteal phases and randomized to a range of phenylalanine intakes (2.5–22.5 mg/kg/day) across multiple study days. Each participant may complete up to seven test days per phase to gather requirement data at different intake levels, and the goal is to enroll at least seven participants per intake level. The protocol is modeled on previously published isotope-based work from the same lab that defined amino acid needs in pregnancy, lactation, and childhood.

Who should consider this trial

Good fit: Ideal candidates are healthy menstruating females aged 20–35 with regular 21–35 day cycles, BMI 18–28 kg/m2, not pregnant or breastfeeding and not using hormonal contraceptives or hormone therapy.

Not a fit: People using hormonal birth control, hormone therapy, those who are pregnant, breastfeeding, recently postpartum, have irregular cycles, metabolic/endocrine disorders, or who follow non-traditional diets are unlikely to benefit or be eligible.

Why it matters

Potential benefit: If successful, the results could support female-specific phenylalanine recommendations that account for menstrual-phase metabolic differences and improve dietary guidance.

How similar studies have performed: Related isotope-based indicator amino acid oxidation studies by the Elango Lab and others have been successfully used to determine amino acid requirements in pregnant, nonpregnant, lactating women and children.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* People with menstrual cycles
* Between the ages of 20 to 35y
* Regular menstrual cycle (21-35 day cycle) for the past 12 months
* Body mass index (BMI) of between 18 and 28 kg/m2
* Free from pre-existing health conditions

Exclusion Criteria:

* People who are currently using hormonal birth control or any contraceptive that would affect sex hormones
* People on hormone therapy
* People with an abnormal menstrual cycle history
* People with non-traditional dietary practices
* Recent weight loss/weight gain
* People with a history of endocrine disorders
* People who are pregnant
* People who are breastfeeding
* People who have given birth in the last 18 months
* People who depend on medication that affects normal metabolism. Any medication that alters normal body metabolism would skew the results and compromise the validity of the data set.
* People with a metabolic, neurological, genetic, or immune disorder likely to affect nutritional requirements or overall body metabolism.

Where this trial is running

Vancouver, British Columbia

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Menstrual Cycle
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.