Each Participant Will be Studied Over 5 Dietary Periods, Each Over 9dNCT07151625
Protein Complementation of Plant-based Diets.
A study testing Diet, whole food provided to participants over 5 x 9 day period and Diet in people with Each Participant Will be Studied Over 5 Dietary Periods, Each Over 9d, run by The Hospital for Sick Children at 1 site in Canada.
Trial summary
Amino acids are the building blocks of proteins which are needed by the body for growth, and bodily functions. If even one amino acid is in short supply, this will negatively affect growth and various functions in the body. Read more about this study
- Who is it for?
- Ages 18 to 79 years
- Conditions the study is for
- Each Participant Will be Studied Over 5 Dietary Periods, Each Over 9d
- What is being tested?
- Diet, whole food provided to participants over 5 x 9 day period and Diet
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteCanada
- Study dates
- 1 Oct 2025to 30 Sep 2029
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 18 to 79 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 1) Young Adults:
- Adults, age 18 - 39 yrs, Healthy with no known clinical condition which would affect protein or AA metabolism, ex. Diabetes, Stable Body Weight (no more than 5 lb weight loss or gain in the past 3 months)
- Not on any medications that could affect protein or amino acid metabolism e.g. steroids.
- Fasting blood glucose, hemoglobin A1C (HbA1c), urea and creatinine within normal ranges for age.
- 2) Older Adults:
- Adults, aged 60-69 and 70-79 years, Healthy with no known clinical condition which would affect protein or AA metabolism, ex. Diabetes, Stable Body Weight (no more than 5 lb weight loss or gain in the past 3 months)
- Not on any medications that could affect protein or amino acid metabolism e.g. steroids,
- Fasting blood glucose, hemoglobin A1C (HbA1c), urea and creatinine within normal ranges for age.
Who cannot join
- Unwillingness to participate or unable to tolerate the diet
- Recent history of weight loss within the last 3 months or on a weight reducing diet Inability to tolerate study diets (ex. Allergy to ingredients).
- Significant caffeine consumption (>2 cups per day)
- Significant alcohol consumption (>1 drink per day i.e. 1 beer or ½ glass of wine).
- Fasting blood glucose, hemoglobin A1C (HbA1c), urea and creatinine outside of normal ranges for age.
- On medications known to affect protein and AA metabolism, renal failure, liver disease, unable to ambulate independently.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site
The Hospital for Sick Children
Toronto, Ontario, M5S 1A8
Glenda Courtney-Martin, PhD, RD, 4168135744, glenda.courtney-martin@sickkids.ca
Mahroukh Rafii, BSc, 416-813-7454, mahroukh.rafii@sickkids.ca
About this study
Official title: To Complement or Not Complement- Is Protein Complementation at Each Meal Necessary When Consuming Plant-based Diets?
Amino acids are the building blocks of proteins which are needed by the body for growth, and bodily functions. If even one amino acid is in short supply, this will negatively affect growth and various functions in the body. Animal foods like meat, fish and chicken contain all the amino acids needed by the body in the correct proportion. These foods are considered high quality protein foods. However plant proteins like lentils, wheat, rice are low in at least one amino acid. This means that plant proteins are considered low quality proteins.
Data from the investigators lab and others show that when eating plant foods, combining grains and legumes like rice and beans, peanut butter and bread, (protein complementation) will provide a complete protein which contains all the amino acids needed by the body. However, some maintain that it is not necessary to combine foods like grains and legumes in the same meal as long as all the amino acids are consumed within a 24h period. This has never been tested.
The goal of this study is to compare the effects non-complementation to protein complementization on whole body protein metabolism in young and older adults.
Read the detailed description
Complementation of plant proteins with complementary amino acid profile (cereal grain + legume) in each meal can improve the protein quality of plant based diets. However, some maintain that if a variety of plant foods are consumed throughout the day, all essential amino acids are provided and protein complementation at each meal is unnecessary. This assumption has NEVER been tested, yet it forms the basis of current expert recommendations for vegetarian diets. Evidence from the investigators lab and others demonstrate that there is no storage pool of amino acids in the body; when one amino acid is deficient in the diet for protein synthesis, all others are in relative excess and are oxidized resulting in poor growth and lower rates of protein synthesis. Therefore, current recommendations for plant based diet consumption could be misleading.
Skeletal muscle plays an important role in the adaptations of body proteins to nutritional changes and during stress. Therefore, knowledge of skeletal muscle response to changes in dietary protein intake from animal to plant based protein is an important prerequisite to understand the body's capacity, especially in the elderly, to adapt to alterations in dietary protein quality from animal to plant based, whether in complementation or non-complementation fashion. The contribution of skeletal muscle to protein breakdown is calculated by measuring urinary 3-methylhistidine. This amino acid is produced in muscle from post-translational modification of histidine and released from actin and myosin. It is not reutilized for protein synthesis but is excreted in the urine. Therefore, the urinary output of 3-methylhistidine is a quantitative index of daily muscle protein breakdown.
Objectives:
- To assess whole-body protein metabolism (WBPM) (protein synthesis, protein breakdown and protein balance) using a single dose [15N]glycine and measuring cumulative excretion of [15N]urea in urine in human adult consuming a PB diet provided in a complementary or non-complementary fashion in males and females 18 -39, 60-69 and 70-79 years and
- To assess the contribution of skeletal muscle to protein breakdown by measuring urinary 3-methyhistidine.
Hypothesis:
Protein synthesis and balance will be lower, but breakdown will be higher in the non-complementation PB diets compared to omnivorous diet (control) and lacto-vegetarian diet.
- Being tested
- Diet, whole food provided to participants over 5 x 9 day period, Diet
- Keywords
- protein complementation, whole body protein turnover, protein synthesis, protein breakdown, protein balance, humans
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Diet, whole food provided to participants over 5 x 9 day periodOther
5 diets provided to participants over 9 days each and whole body protein synthesis, protein breakdown and protein balance assessed after each period.
DietOther
5 different diet types
| Study group | Role | What they receive |
|---|---|---|
| protein synthesis, breakdown and balance assessed after exposure to 5 diets consumed over 9d | Other | Not described Receives: Other: Diet, whole food provided to participants over 5 x 9 day period; Other: Diet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Whole-body protein metabolism (WBPM): protein synthesis, protein breakdown and protein balance.
Protein synthesis, protein breakdown and protein balance (synthesis-breakdown) will be calculated from urinary urea enrichments using standard equations previously used by the investigators and others. The skeletal muscle content of 3-methylhistidine will be used to compute the rate of whole body muscle protein breakdown from the daily urinary excretion of the 3-methylhistidine. Non-muscle component will be computed by subtracting the muscle protein breakdown (3-methylhistidine) from the whole-body protein breakdown obtained from the urine [15N]urea data.
Measured: 9 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Sep 2025
- Study start1 Oct 2025 (estimated)
- Primary completion30 Sep 2029 (estimated)
- Study completion30 Sep 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Each Participant Will be Studied Over 5 Dietary Periods, Each Over 9dStudies of the same condition, open and under way.
- 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
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- The Hospital for Sick Children
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Glenda Courtney-Martin, The Hospital for Sick Children
- Investigators
- Glenda Courtney-Martin, PhD, RD, Principal investigator, Research Institute, The Hospital for Sick Children
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07151625
- Sponsor's protocol ID
- 3667
- Other IDs
- PJT-198014
- Status last verified
- Aug 2025
- First submitted
- 18 Aug 2025
- Last updated
- 3 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be shared with other researchers unless doing a metanalysis and data is requested. The information will be uploaded as per the ICMJE requirements at the end of the study.
Study at a glance
From the registry record, last updated by the sponsor on 3 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- To Complement or Not Complement- Is Protein Complementation at Each Meal Necessary When Consuming Plant-based Diets?
- ClinicalTrials.gov ID
- NCT07151625
- Acronym / sponsor ID
- 3667
- Keywords
- protein complementation, whole body protein turnover, protein synthesis, protein breakdown, protein balance, humans
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- The Hospital for Sick ChildrenUniversity, hospital or other
- Study start
- 1 Oct 2025 (estimated)
- Primary completion
- 30 Sep 2029 (estimated)
- Study completion
- 30 Sep 2029 (estimated)
- First posted
- 3 Sep 2025 (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.
Amino acids are the building blocks of proteins which are needed by the body for growth, and bodily functions. If even one amino acid is in short supply, this will negatively affect growth and various functions in the body. Animal foods like meat, fish and chicken contain all the amino acids needed by the body in the correct proportion. These foods are considered high quality protein foods. However plant proteins like lentils, wheat, rice are low in at least one amino acid. This means that plant proteins are considered low quality proteins.
Data from the investigators lab and others show that when eating plant foods, combining grains and legumes like rice and beans, peanut butter and bread, (protein complementation) will provide a complete protein which contains all the amino acids needed by the body. However, some maintain that it is not necessary to combine foods like grains and legumes in the same meal as long as all the amino acids are consumed within a 24h period. This has never been tested.
The goal of this study is to compare the effects non-complementation to protein complementization on whole body protein metabolism in young and older adults.
Detailed description
Complementation of plant proteins with complementary amino acid profile (cereal grain + legume) in each meal can improve the protein quality of plant based diets. However, some maintain that if a variety of plant foods are consumed throughout the day, all essential amino acids are provided and protein complementation at each meal is unnecessary. This assumption has NEVER been tested, yet it forms the basis of current expert recommendations for vegetarian diets. Evidence from the investigators lab and others demonstrate that there is no storage pool of amino acids in the body; when one amino acid is deficient in the diet for protein synthesis, all others are in relative excess and are oxidized resulting in poor growth and lower rates of protein synthesis. Therefore, current recommendations for plant based diet consumption could be misleading.
Skeletal muscle plays an important role in the adaptations of body proteins to nutritional changes and during stress. Therefore, knowledge of skeletal muscle response to changes in dietary protein intake from animal to plant based protein is an important prerequisite to understand the body's capacity, especially in the elderly, to adapt to alterations in dietary protein quality from animal to plant based, whether in complementation or non-complementation fashion. The contribution of skeletal muscle to protein breakdown is calculated by measuring urinary 3-methylhistidine. This amino acid is produced in muscle from post-translational modification of histidine and released from actin and myosin. It is not reutilized for protein synthesis but is excreted in the urine. Therefore, the urinary output of 3-methylhistidine is a quantitative index of daily muscle protein breakdown.
Objectives:
- To assess whole-body protein metabolism (WBPM) (protein synthesis, protein breakdown and protein balance) using a single dose [15N]glycine and measuring cumulative excretion of [15N]urea in urine in human adult consuming a PB diet provided in a complementary or non-complementary fashion in males and females 18 -39, 60-69 and 70-79 years and
- To assess the contribution of skeletal muscle to protein breakdown by measuring urinary 3-methyhistidine.
Hypothesis:
Protein synthesis and balance will be lower, but breakdown will be higher in the non-complementation PB diets compared to omnivorous diet (control) and lacto-vegetarian diet.
Study design
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| protein synthesis, breakdown and balance assessed after exposure to 5 diets consumed over 9d | Other | Other: Diet, whole food provided to participants over 5 x 9 day period, Other: Diet |
Who may qualify
- Ages
- 18 to 79 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (8 listed)
- 1) Young Adults:
- Adults, age 18 - 39 yrs, Healthy with no known clinical condition which would affect protein or AA metabolism, ex. Diabetes, Stable Body Weight (no more than 5 lb weight loss or gain in the past 3 months)
- Not on any medications that could affect protein or amino acid metabolism e.g. steroids.
- Fasting blood glucose, hemoglobin A1C (HbA1c), urea and creatinine within normal ranges for age.
- Adults, aged 60-69 and 70-79 years, Healthy with no known clinical condition which would affect protein or AA metabolism, ex. Diabetes, Stable Body Weight (no more than 5 lb weight loss or gain in the past 3 months)
Key exclusion criteria (6 listed)
- Unwillingness to participate or unable to tolerate the diet
- Recent history of weight loss within the last 3 months or on a weight reducing diet Inability to tolerate study diets (ex. Allergy to ingredients).
- Significant caffeine consumption (>2 cups per day)
- Significant alcohol consumption (>1 drink per day i.e. 1 beer or ½ glass of wine).
- Fasting blood glucose, hemoglobin A1C (HbA1c), urea and creatinine outside of normal ranges for age.
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 |
|---|---|---|
| Diet, whole food provided to participants over 5 x 9 day period5 diets provided to participants over 9 days each and whole body protein synthesis, protein breakdown and protein balance assessed after each period. | Other | protein synthesis, breakdown and balance assessed after exposure to 5 diets consumed over 9d |
| Diet5 different diet types | Other | protein synthesis, breakdown and balance assessed after exposure to 5 diets consumed over 9d |
Primary outcome
Whole-body protein metabolism (WBPM): protein synthesis, protein breakdown and protein balance.
Time frame: 9 days
Protein synthesis, protein breakdown and protein balance (synthesis-breakdown) will be calculated from urinary urea enrichments using standard equations previously used by the investigators and others. The skeletal muscle content of 3-methylhistidine will be used to compute the rate of whole body muscle protein breakdown from the daily urinary excretion of the 3-methylhistidine. Non-muscle component will be computed by subtracting the muscle protein breakdown (3-methylhistidine) from the whole-body protein breakdown obtained from the urine [15N]urea data.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Sep 2025.
- Individual participant dataSharing planned: No. Individual participant data will not be shared with other researchers unless doing a metanalysis and data is requested. The information will be uploaded as per the ICMJE requirements at the end of the study.
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.
Glenda Courtney-Martin, PhD, RD principal investigator
Research Institute, The Hospital for Sick Children
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Diet, whole food provided to participants over 5 x 9 day period and Diet in people with Each Participant Will be Studied Over 5 Dietary Periods, Each Over 9d, run by The Hospital for Sick Children 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 8 inclusion and 6 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: opening soon, as of the sponsor's last update on 3 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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Mahroukh Rafii, BSc (416-813-7454, mahroukh.rafii@sickkids.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Whole-body protein metabolism (WBPM): protein synthesis, protein breakdown and protein balance. (time frame: 9 days). 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 3 Sep 2025.