Parkinson DiseaseNCT05437640
Optimizing Protein Patterns for Skeletal Muscle Preservation and Sleep in the Medical Management of Parkinson Disease
A study testing Protein Redistribution Diet and Protein Consistent Diet in people with Parkinson Disease, run by University of Alabama at Birmingham at 1 site in United States.
Trial summary
The purpose of this pilot study is to generate preliminary data on the impact of the dietary protein pattern on markers of skeletal muscle health and drug efficacy in Parkinson disease. Read more about this study
- Who is it for?
- Ages 45 to 99 years
- Conditions the study is for
- Parkinson Disease
- What is being tested?
- Protein Redistribution Diet and Protein Consistent Diet
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 12 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Oct 2022to 25 Nov 2024
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 45 to 99 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Clinical diagnosis of idiopathic PD for 5 or more years
- 45 years or older
- On a stable levodopa regimen for 3 or more months
- Self-reported to experience motor fluctuations
Who cannot join
- Following a specific diet that would preclude participation
- Renal disease
- Deep brain stimulation
- Known narcolepsy
- Untreated sleep apnea
- Any condition that, in the opinion of the investigator, will preclude the participant from successfully or safely completing study procedures
Trial locations and contacts
1 site in 1 country.
United States1 site
University of Alabama at Birmingham
Birmingham, Alabama, 35233
About this study
The purpose of this pilot study is to generate preliminary data on the impact of the dietary protein pattern on markers of skeletal muscle health and drug efficacy in Parkinson disease.
Read the detailed description
Parkinson's disease (PD) is a complex neurological disease that affects ~6.1 million people worldwide - mostly older adults >60 years. The most effective treatment for PD is dopaminergic therapy, particularly levodopa (Ldopa). People with PD have variable responses to Ldopa, including degrees of motor fluctuations (MF) throughout the day. The half-life of Ldopa is ~1.5 h and therefore, dosage and timing are essential to mitigate MF. Ldopa is a large neutral amino acid (LNAA), and the bioavailability of Ldopa is compromised when simultaneously ingested with LNAA (e.g., leucine). Both Ldopa and LNAAs from food are absorbed through the same intestinal transporter, but LNAAs from food are preferentially absorbed by the enterocyte, limiting the bioavailability of Ldopa. Thus, the scientific community often recommends the protein-redistribution diet (PRD). With PRD, patients limit protein (<10 g) at the desired time of medication efficacy (daytime) and meet their protein needs during the evening meal (~70+g). There are deleterious implications of the PRD for older adults with PD; consumption of >30 g of protein, in a single meal, will not sufficiently increase muscle protein synthesis. Additionally, the impact of the PRD on skeletal muscle quality and function has not been determined, and it is unclear, based on prior studies, whether the PRD enhanced drug absorption. Therefore, the objective of this study is to address these gaps in knowledge. This study will quantify the effects of dietary protein pattern on skeletal muscle in PD; determine the effects of dietary protein pattern on sleep quality in PD. This study is an acute, 5-week, crossover intervention with PD participants randomly assigned to first adhere to either the PCD or PRD. Participants will receive diet prescriptions and meal plans for their respective diet, and outcome measures will be assessed at days 0, 14, 21, and 35.
- Conditions
- Parkinson Disease
- Being tested
- Protein Redistribution Diet, Protein Consistent Diet
- Keywords
- Parkinson Disease, Diet, Protein, Skeletal Muscle, Sleep
- Medical subject headings
- Parkinson Disease
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Protein Redistribution DietBehavioural
Also called PRD
PD participants will be instructed by a Registered Dietitian to consume 10 grams or less of protein until their evening meal. They will then consume a high protein evening meal to meet their protein needs. They will receive one-on-one education and supportive materials to follow diet plan.
Protein Consistent DietBehavioural
Also called PCD
PD participants will be instructed by a Registered Dietitian to consume 20-30 grams of protein per meal. They will receive one-on-one education and supportive materials to follow diet plan.
| Study group | Role | What they receive |
|---|---|---|
| Protein Redistribution Diet | Active comparator | PD participants may first be randomized to follow the Protein Redistribution Diet followed by the Protein Consistent Diet. Receives: Behavioral: Protein Redistribution Diet |
| Protein Consistent Diet | Active comparator | PD participants may first be randomized to follow the Protein Consistent Diet followed by the Protein Redistribution Diet. Receives: Behavioral: Protein Consistent Diet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Markers of Skeletal Muscle Metabolism GDF15
Serum Growth Differentiation Factor 15 (GDF15)
Measured: Baseline to 5 weeks
Change in Markers of Skeletal Muscle Metabolism FGF21
Serum Fibroblast Growth Factor 21 (FGF21)
Measured: Baseline to 5 weeks
Change in Handgrip Strength
Handgrip strength assessed via digital dynamometer
Measured: Baseline to 5 weeks
Change in Sleep Efficiency
Sleep efficiency assessed via actigraphy
Measured: Baseline to 5 weeks
Change in Motor Symptoms
Motor symptoms assessed via the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part II. Part II ranges from 0-52 with higher scores indicating greater symptom severity.
Measured: Baseline to 5 weeks
Secondary outcomes (2)
Change in Physical Activity
Physical activity assessed via actigraphy
Measured: Baseline to 5 weeks
Change in Total Parkinson Symptoms
Parkinson-related symptoms assessed by total MDS-UPDRS score
Measured: Baseline to 5 weeks. Total score ranges from 0-260 with higher scores indicating greater symptom severity.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Jun 2022
- Study start1 Oct 2022
- Primary completion25 Nov 2024
- Study completion25 Nov 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Parkinson DiseaseStudies of the same condition, open and under way.
- More trials run by University of Alabama at BirminghamThe 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
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- PD participants randomly assigned to first adhere to either the Protein Consistent Diet or Protein Redistribution Diet for 2 weeks. Participants will enter a 1-week washout period between the diets where they follow their typical diet and then follow the other diet prescription for 2 weeks.
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 12 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Alabama at Birmingham
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Christine Ferguson, PhD, RD, LD, University of Alabama at Birmingham
- Investigators
- Christine C Ferguson, PhD, Principal investigator, University of Alabama at Birmingham
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05437640
- Sponsor's protocol ID
- IRB-300009538
- Other IDs
- P30DK056336
- Status last verified
- May 2026
- First submitted
- 23 Jun 2022
- Last updated
- 22 Jun 2026
- Results posted
- Yes, on ClinicalTrials.gov
- 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 22 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Optimizing Protein Patterns for Skeletal Muscle Preservation and Sleep in the Medical Management of Parkinson Disease
- ClinicalTrials.gov ID
- NCT05437640
- Acronym / sponsor ID
- IRB-300009538
- Conditions
- Parkinson Disease
- Keywords
- Parkinson Disease, Diet, Protein, Skeletal Muscle, Sleep
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 12 participants (actual)
- Lead sponsor
- University of Alabama at BirminghamUniversity, hospital or other
- Collaborators
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Study start
- 1 Oct 2022 (actual)
- Primary completion
- 25 Nov 2024 (actual)
- Study completion
- 25 Nov 2024 (actual)
- First posted
- 29 Jun 2022 (actual)
- Results
- Posted 15 Jun 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this pilot study is to generate preliminary data on the impact of the dietary protein pattern on markers of skeletal muscle health and drug efficacy in Parkinson disease.
Detailed description
Parkinson's disease (PD) is a complex neurological disease that affects ~6.1 million people worldwide - mostly older adults >60 years. The most effective treatment for PD is dopaminergic therapy, particularly levodopa (Ldopa). People with PD have variable responses to Ldopa, including degrees of motor fluctuations (MF) throughout the day. The half-life of Ldopa is ~1.5 h and therefore, dosage and timing are essential to mitigate MF. Ldopa is a large neutral amino acid (LNAA), and the bioavailability of Ldopa is compromised when simultaneously ingested with LNAA (e.g., leucine). Both Ldopa and LNAAs from food are absorbed through the same intestinal transporter, but LNAAs from food are preferentially absorbed by the enterocyte, limiting the bioavailability of Ldopa. Thus, the scientific community often recommends the protein-redistribution diet (PRD). With PRD, patients limit protein (<10 g) at the desired time of medication efficacy (daytime) and meet their protein needs during the evening meal (~70+g). There are deleterious implications of the PRD for older adults with PD; consumption of >30 g of protein, in a single meal, will not sufficiently increase muscle protein synthesis. Additionally, the impact of the PRD on skeletal muscle quality and function has not been determined, and it is unclear, based on prior studies, whether the PRD enhanced drug absorption. Therefore, the objective of this study is to address these gaps in knowledge. This study will quantify the effects of dietary protein pattern on skeletal muscle in PD; determine the effects of dietary protein pattern on sleep quality in PD. This study is an acute, 5-week, crossover intervention with PD participants randomly assigned to first adhere to either the PCD or PRD. Participants will receive diet prescriptions and meal plans for their respective diet, and outcome measures will be assessed at days 0, 14, 21, and 35.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
- Model description
- PD participants randomly assigned to first adhere to either the Protein Consistent Diet or Protein Redistribution Diet for 2 weeks. Participants will enter a 1-week washout period between the diets where they follow their typical diet and then follow the other diet prescription for 2 weeks.
| Arm | Type | Receives |
|---|---|---|
| Protein Redistribution Diet | Active comparator | Behavioral: Protein Redistribution DietPD participants may first be randomized to follow the Protein Redistribution Diet followed by the Protein Consistent Diet. |
| Protein Consistent Diet | Active comparator | Behavioral: Protein Consistent DietPD participants may first be randomized to follow the Protein Consistent Diet followed by the Protein Redistribution Diet. |
Who may qualify
- Ages
- 45 to 99 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Clinical diagnosis of idiopathic PD for 5 or more years
- 45 years or older
- On a stable levodopa regimen for 3 or more months
- Self-reported to experience motor fluctuations
Key exclusion criteria (6 listed)
- Following a specific diet that would preclude participation
- Renal disease
- Deep brain stimulation
- Known narcolepsy
- Untreated sleep apnea
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 |
|---|---|---|
| Protein Redistribution DietAlso: PRDPD participants will be instructed by a Registered Dietitian to consume 10 grams or less of protein until their evening meal. They will then consume a high protein evening meal to meet their protein needs. They will receive one-on-one education and supportive materials to follow diet plan. | Behavioural | Protein Redistribution Diet |
| Protein Consistent DietAlso: PCDPD participants will be instructed by a Registered Dietitian to consume 20-30 grams of protein per meal. They will receive one-on-one education and supportive materials to follow diet plan. | Behavioural | Protein Consistent Diet |
Primary outcome
Change in Markers of Skeletal Muscle Metabolism GDF15
Time frame: Baseline to 5 weeks
Serum Growth Differentiation Factor 15 (GDF15)
Change in Markers of Skeletal Muscle Metabolism FGF21
Time frame: Baseline to 5 weeks
Serum Fibroblast Growth Factor 21 (FGF21)
Change in Handgrip Strength
Time frame: Baseline to 5 weeks
Handgrip strength assessed via digital dynamometer
Change in Sleep Efficiency
Time frame: Baseline to 5 weeks
Sleep efficiency assessed via actigraphy
Change in Motor Symptoms
Time frame: Baseline to 5 weeks
Motor symptoms assessed via the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part II. Part II ranges from 0-52 with higher scores indicating greater symptom severity.
2 secondary outcomes
Change in Physical Activity
Time frame: Baseline to 5 weeks
Change in Total Parkinson Symptoms
Time frame: Baseline to 5 weeks. Total score ranges from 0-260 with higher scores indicating greater symptom severity.
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Jun 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- 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.
Christine C Ferguson, PhD principal investigator
University of Alabama at Birmingham
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Protein Redistribution Diet and Protein Consistent Diet in people with Parkinson Disease, run by University of Alabama at Birmingham at 1 site in United States.
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 4 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: finished, as of the sponsor's last update on 22 Jun 2026. 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 United States. 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?
Yes. Results are posted in the registry (first posted 15 Jun 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
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?
Change in Markers of Skeletal Muscle Metabolism GDF15 (time frame: Baseline to 5 weeks). The study lists 5 primary outcomes in all. 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 22 Jun 2026.