PregnancyNCT06519071
Tryptophan Requirements During Pregnancy
A study testing Tryptophan Intake in people with Pregnancy, run by University of British Columbia at 1 site in Canada.
Trial summary
Pregnancy is an important period of life where there is an increased need for nutrients including protein and amino acids from food. The current protein and amino acids dietary recommendations were all established using older methods done in adult men. Read more about this study
- Who is it for?
- Ages 20 to 40 years, women onlyHealthy volunteers can take part
- Conditions the study is for
- Pregnancy
- What is being tested?
- Tryptophan Intake
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 29 participants
- Where
- 1 siteCanada
- Study dates
- 20 Jul 2023to 18 Jul 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 20 to 40 years
- Women only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Cis-gendered pregnant woman.
- 20-40 years of age.
- Pregnant with a single child.
- Between 11-20 weeks of gestation or 31-40 weeks of gestation.
- Free of chronic diseases/acute diseases and have a full range of physical mobility.
Who cannot join
- Women who are not pregnant.
- Women who are pregnant with more than one child (this changes amino acid demands) or were pregnant in the 6 months before the current pregnancy.
- Women with a history of spontaneous abortion (within the last 6 months) or preterm birth.
- Women not in good health or have a metabolic, cardiovascular, neurological, genetic, or immune disorder, including gestational diabetes, preeclampsia, pregnancy-related anemia, or pregnancy-related jaundice.
- Claustrophobic women (a clear hood will be placed, which can easily be removed, over the participants head for approximately 20 min to measure energy expenditure).
- Women who are substance dependent (i.e., alcohol, tobacco, illicit drugs).
Show all 10Show fewer
- Women who have severe nausea/vomiting throughout their pregnancy.
- Women under the age of 20 years and over the age of 40 years.
- Women who have lost weight (approximately 1.5kg or more) during their current pregnancy.
- Women with a pre-pregnancy Body Mass Index (BMI) under 19 or over 28 〖kg/m〗^2.
Trial locations and contacts
1 site in 1 country.
Canada1 site
BC Children's Hospital Research Institute, University of British Columbia
Vancouver, British Columbia, V5Z4H4
About this study
Official title: Determining Dietary Tryptophan Requirements In Healthy Pregnant Women Using The Indicator Amino Acid Oxidation Method
Pregnancy is an important period of life where there is an increased need for nutrients including protein and amino acids from food. The current protein and amino acids dietary recommendations were all established using older methods done in adult men. Then protein and amino acids requirements for all stages of pregnancy were calculated without accounting for changing demands in each trimester. Therefore, another more precise method is needed to better understand how much amino acids (in this study tryptophan) women need during pregnancy.
In the current study, the investigators are going to apply the Indicator Amino Acid Oxidation (IAAO) method to measure the dietary tryptophan needs in a healthy pregnancy. This method is a noninvasive, quick, and reliable technique that uses a stable isotope-labeled amino acid. The stable isotope tracer is a labeled amino acid, which is colorless, odorless, tasteless, and completely safe; they are present in the air, water and food. Amino acids are mostly made of Carbon-12 (12C), whereas the isotope tracer contains Carbon-13 (13C). The tracer can be detected in breath and urine samples with special equipment because it looks different than the rest of the amino acids in the body. In Elango lab, the investigators have done similar studies, using the same technique in children, nonpregnant women and pregnant women. This will allow us to measure tryptophan needs in pregnancy.
Read the detailed description
Pre-Study:
All participants will arrive following a 10-12 hrs overnight fasting, to allow the anthropometric measurements, biochemical, and dietary assessments. Fasting blood glucose by finger prick will be used to screen for gestational diabetes. The presence of protein, glucose, ketones, leukocytes, and blood in urine will be assessed using urinalysis strips as potential indicators of gestational diabetes and preeclampsia. For the anthropometric assessment, weight and height will be measured and body composition will be determined using skinfold thickness measurements and Bioelectrical Impedance Analysis (BIA). A brief medical history will be obtained to screen for medication use, substance use, previous pregnancies, and overall health. For the dietary assessment, energy requirements will be determined using Resting Energy Expenditure (REE) by continuous, open-circuit indirect calorimetry. In addition to two-days detailed dietary records to estimate participants' calorie, protein, and tryptophan intake.
Study Day:
Participants are expected to arrive following a 10-12 hrs overnight fasting, as mentioned above, anthropometric measurements, fasting blood glucose testing and urine strip analysis will be repeated at the beginning of each study day. On the study day, the investigator will randomly assign the participant a test tryptophan intake (ranging between 1 to 14 mg.kg.d) and will receive an 8-hourly isocaloric and isonitrogenous meal. Based on Resting Energy Expenditure determined during the pre-study day, each meal will provide daily adequate energy and adequate protein (at 1.5 g.kg.d) to ensure that the Indicator Amino Acid Oxidation (IAAO) response is due to the different test tryptophan intakes and not from the limited energy and/or protein. During the study days, participants will be allowed to have the prepared study diets and water only.
Sample Collection:
Three baseline breath samples will be collected at 45, 30, and 15 min before isotope infusion. Thereafter isotope administration (meal 5 - 8), breath samples will be collected at 150, 180, 195, 210, 225, and 240 min during the metabolic steady state. Urine samples will be collected at 45 min before isotope infusion (meal 5) and two samples at 180, and 240 min after the tracer infusion. One blood sample will be collected to measure tryptophan and four related metabolites within the kynurenine and serotonin pathway (plasma kynurenine, xanthurenic acid, quinolinic acid, and serotonin), and B vitamins (plasma B6, B12, and B9) then compared between early and later stages of gestation in response to different tryptophan intakes.
- Conditions
- Pregnancy
- Being tested
- Tryptophan Intake
- Keywords
- Amino Acids, Tryptophan, Pregnancy, Indicator Amino Acid Oxidation, Stable Isotopes
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Tryptophan IntakeOther
Each hourly meal will provide one-twelfth of the participants' daily energy requirements as estimated by 1.7 Resting Energy Expenditure and adequate protein (at 1.5 g.kg.d), to maintain a metabolic steady state. The liquid shake contains protein-free powder orange-flavored drink crystals, corn oil, and water.
| Study group | Role | What they receive |
|---|---|---|
| Tryptophan Intake | Experimental | Randomly assign the participant to receive a test tryptophan oral intake (ranging between 1 to 14 mg.kg.d) as an 8-hourly isocaloric and isonitrogenous meal that consist of a liquid formula shake and protein-free cookies. Receives: Other: Tryptophan Intake |
What is being measured
The primary outcome is the main question the study is designed to answer.
Carbon 13 Oxidation
Urine and breath will be collected to measure the rate of oxidation of L-[1-13C]phenylalanine oxidation.
Measured: 8 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Jul 2024
- Study start20 Jul 2023
- Primary completion20 Mar 2025
- Study completion18 Jul 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for PregnancyStudies of the same condition, open and under way.
- More trials run by University of British ColumbiaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 29 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of British Columbia
- Sponsor type
- University, hospital or other
- Collaborators
- Canadian Institutes of Health Research (CIHR)
- Responsible party
- Principal investigator, Rajavel Elango, PhD, University of British Columbia
- Investigators
- Rajavel Elango, PhD, Principal investigator, University of British Columbia
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06519071
- Sponsor's protocol ID
- H23-01187
- Status last verified
- Sep 2025
- First submitted
- 2 Aug 2023
- Last updated
- 16 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 16 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Determining Dietary Tryptophan Requirements In Healthy Pregnant Women Using The Indicator Amino Acid Oxidation Method
- ClinicalTrials.gov ID
- NCT06519071
- Acronym / sponsor ID
- H23-01187
- Conditions
- Pregnancy
- Keywords
- Amino Acids, Tryptophan, Pregnancy, Indicator Amino Acid Oxidation, Stable Isotopes
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 29 participants (actual)
- Lead sponsor
- University of British ColumbiaUniversity, hospital or other
- Collaborators
- Canadian Institutes of Health Research (CIHR)
- Study start
- 20 Jul 2023 (actual)
- Primary completion
- 20 Mar 2025 (actual)
- Study completion
- 18 Jul 2025 (actual)
- First posted
- 25 Jul 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Pregnancy is an important period of life where there is an increased need for nutrients including protein and amino acids from food. The current protein and amino acids dietary recommendations were all established using older methods done in adult men. Then protein and amino acids requirements for all stages of pregnancy were calculated without accounting for changing demands in each trimester. Therefore, another more precise method is needed to better understand how much amino acids (in this study tryptophan) women need during pregnancy.
In the current study, the investigators are going to apply the Indicator Amino Acid Oxidation (IAAO) method to measure the dietary tryptophan needs in a healthy pregnancy. This method is a noninvasive, quick, and reliable technique that uses a stable isotope-labeled amino acid. The stable isotope tracer is a labeled amino acid, which is colorless, odorless, tasteless, and completely safe; they are present in the air, water and food. Amino acids are mostly made of Carbon-12 (12C), whereas the isotope tracer contains Carbon-13 (13C). The tracer can be detected in breath and urine samples with special equipment because it looks different than the rest of the amino acids in the body. In Elango lab, the investigators have done similar studies, using the same technique in children, nonpregnant women and pregnant women. This will allow us to measure tryptophan needs in pregnancy.
Detailed description
Pre-Study:
All participants will arrive following a 10-12 hrs overnight fasting, to allow the anthropometric measurements, biochemical, and dietary assessments. Fasting blood glucose by finger prick will be used to screen for gestational diabetes. The presence of protein, glucose, ketones, leukocytes, and blood in urine will be assessed using urinalysis strips as potential indicators of gestational diabetes and preeclampsia. For the anthropometric assessment, weight and height will be measured and body composition will be determined using skinfold thickness measurements and Bioelectrical Impedance Analysis (BIA). A brief medical history will be obtained to screen for medication use, substance use, previous pregnancies, and overall health. For the dietary assessment, energy requirements will be determined using Resting Energy Expenditure (REE) by continuous, open-circuit indirect calorimetry. In addition to two-days detailed dietary records to estimate participants' calorie, protein, and tryptophan intake.
Study Day:
Participants are expected to arrive following a 10-12 hrs overnight fasting, as mentioned above, anthropometric measurements, fasting blood glucose testing and urine strip analysis will be repeated at the beginning of each study day. On the study day, the investigator will randomly assign the participant a test tryptophan intake (ranging between 1 to 14 mg.kg.d) and will receive an 8-hourly isocaloric and isonitrogenous meal. Based on Resting Energy Expenditure determined during the pre-study day, each meal will provide daily adequate energy and adequate protein (at 1.5 g.kg.d) to ensure that the Indicator Amino Acid Oxidation (IAAO) response is due to the different test tryptophan intakes and not from the limited energy and/or protein. During the study days, participants will be allowed to have the prepared study diets and water only.
Sample Collection:
Three baseline breath samples will be collected at 45, 30, and 15 min before isotope infusion. Thereafter isotope administration (meal 5 - 8), breath samples will be collected at 150, 180, 195, 210, 225, and 240 min during the metabolic steady state. Urine samples will be collected at 45 min before isotope infusion (meal 5) and two samples at 180, and 240 min after the tracer infusion. One blood sample will be collected to measure tryptophan and four related metabolites within the kynurenine and serotonin pathway (plasma kynurenine, xanthurenic acid, quinolinic acid, and serotonin), and B vitamins (plasma B6, B12, and B9) then compared between early and later stages of gestation in response to different tryptophan intakes.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Tryptophan Intake | Experimental | Other: Tryptophan IntakeRandomly assign the participant to receive a test tryptophan oral intake (ranging between 1 to 14 mg.kg.d) as an 8-hourly isocaloric and isonitrogenous meal that consist of a liquid formula shake and protein-free cookies. |
Who may qualify
- Ages
- 20 to 40 years
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Cis-gendered pregnant woman.
- 20-40 years of age.
- Pregnant with a single child.
- Between 11-20 weeks of gestation or 31-40 weeks of gestation.
- Free of chronic diseases/acute diseases and have a full range of physical mobility.
Key exclusion criteria (10 listed)
- Women who are not pregnant.
- Women who are pregnant with more than one child (this changes amino acid demands) or were pregnant in the 6 months before the current pregnancy.
- Women with a history of spontaneous abortion (within the last 6 months) or preterm birth.
- Women not in good health or have a metabolic, cardiovascular, neurological, genetic, or immune disorder, including gestational diabetes, preeclampsia, pregnancy-related anemia, or pregnancy-related jaundice.
- Claustrophobic women (a clear hood will be placed, which can easily be removed, over the participants head for approximately 20 min to measure energy expenditure).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Tryptophan IntakeEach hourly meal will provide one-twelfth of the participants' daily energy requirements as estimated by 1.7 Resting Energy Expenditure and adequate protein (at 1.5 g.kg.d), to maintain a metabolic steady state. The liquid shake contains protein-free powder orange-flavored drink crystals, corn oil, and water. | Other | Tryptophan Intake |
Primary outcome
Carbon 13 Oxidation
Time frame: 8 hours
Urine and breath will be collected to measure the rate of oxidation of L-[1-13C]phenylalanine oxidation.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Sep 2025.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Rajavel Elango, PhD principal investigator
University of British Columbia
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Tryptophan Intake in people with Pregnancy, run by University of British Columbia at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 16 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Carbon 13 Oxidation (time frame: 8 hours). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Sep 2025.