Phenylalanine Requirements in the Menstrual Phases
University of British Columbia
15 participants
May 1, 2026
INTERVENTIONAL
Conditions
Summary
Phenylalanine is an essential amino acid that must be obtained through food. Current adult phenylalanine recommendation is based on male-conducted studies and set the same for females. These recommendations may not be appropriate for females, as they do not take into consideration the hormonal changes over the menstrual cycle. The menstrual cycle is a rhythmic hormonal process split into two phases, with hormones regulating metabolism differently. The aim of this study is to find phenylalanine requirement for healthy, menstruating females. An innovative, non-invasive technique utilizing pre-determined diets, safe stable isotopes, and a simple breath collection method will be used. Previous work done by Elango Lab investigators has applied this method to investigate other amino acids in pregnant, non-pregnant, and lactating females as well as in children.
Eligibility
Inclusion Criteria5
- 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 Criteria11
- 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.
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Interventions
Participants consume 8 hourly meals that contain the assigned test phenylalanine intake. Each meal will provide one-twelfth of the participants' daily energy requirements as estimated by 1.5 x Resting Energy Expenditure (REE) and adequate protein at 1.0 g.kg.d, to maintain a metabolic steady state. The meals are in the form of a crystalline amino acid protein shake, and protein-free cookies.
Locations(1)
View Full Details on ClinicalTrials.gov
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NCT07481201