NCT07121010 · University of Pittsburgh
How Animal and Plant Protein Shakes Change the Body's Nutrient and Health Responses
What this study is about
The goal of this clinical trial is to learn how different protein types affect the body's metabolism and immune system in healthy adults.
View original scientific description
The goal of this clinical trial is to learn how different protein types affect the body's metabolism and immune system in healthy adults. The main questions it aims to answer are: Does drinking smoothies with animal-based or plant-based protein change the level of amino acids like leucine in the blood? Does adding leucine to a plant-based smoothie make the body respond like it does to an animal-based smoothie? Participants will: Come to the research clinic for 3 study visits Drink a high-protein smoothie at each visit (one with animal protein, one with plant protein, and one with plant protein + leucine) Give blood samples before and 1 and 3 hours after each smoothie Researchers will look at how the body's metabolism and immune system respond. They are especially interested in a pathway called mTOR, which helps control how cells use nutrients and may be involved in heart disease like atherosclerosis. All smoothies are prepared to meet Halal and Kosher dietary guidelines.
Interventions
DIETARY_SUPPLEMENT
Animal-Based Protein Smoothie
This smoothie is formulated to deliver 50% of its total caloric content from high-quality animal-based protein, such as whey protein isolate or pasteurized egg whites. It is designed to evaluate the postprandial metabolic and immune response to animal-derived protein sources. The smoothie does not contain any added free amino acids and is prepared in a food-safe certified kitchen under standardized conditions. All participants consume the smoothie after an overnight fast to ensure consistency in metabolic assessment.
DIETARY_SUPPLEMENT
Plant-Based Protein Smoothie
This smoothie is formulated to deliver 50% of its total caloric content from plant-based protein, such as pea or rice protein isolate. It is designed to evaluate the postprandial metabolic and immune response to plant-derived protein sources. The smoothie does not contain any added free amino acids and is prepared in a food-safe certified kitchen under standardized conditions. All participants consume the smoothie after an overnight fast to ensure consistency in metabolic assessment.
DIETARY_SUPPLEMENT
Plant-Based Protein Smoothie with Leucine
This smoothie is formulated to deliver 50% of its total caloric content from plant-based protein, using sources such as pea or rice protein isolate. In addition, it is supplemented with pharmaceutical-grade leucine to match the leucine content typically found in animal-based protein sources. The smoothie is designed to assess whether leucine supplementation can modulate the postprandial metabolic and immune response to plant-derived protein. It is prepared in a food-safe certified kitchen and consumed after an overnight fast to maintain consistency across study conditions.
Primary outcome measures
Change in Circulating Serum Leucine Concentration
Time frame: From enrollment to final blood draw at 4 weeks
This outcome measures the change in circulating serum leucine concentration from fasting baseline to 1 and 3 hours postprandially following ingestion of each of the three test meals: animal-based protein, plant-based protein, and plant-based protein supplemented with free leucine. Values will be compared within participants across the three meal conditions to assess how protein source and leucine content affect postprandial amino acid levels. Serum leucine will be quantified using targeted mass spectrometry. Unit of Measure: Micromoles per liter (μmol/L)
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Age 18-65 years
- BMI 18.5-29.9 kg/m²
- Generally healthy, without known chronic illness and/or treatment with chronic medications
- Willing to comply with dietary restrictions and study procedures
- Not currently following a prescribed or restrictive diet (for example, vegan, ketogenic or high-protein regimen) or regularly taking high-protein supplements
Exclusion criteria
- History of cardiovascular disease, diabetes, or autoimmune disorders
- Active use of anti-inflammatory, immunomodulatory, or lipid-lowering medications
- Renal or hepatic dysfunction
- Pregnancy or breastfeeding
- Allergies or intolerances to components of study meals. A list of the smoothie ingredients will be sent to the potential participant with the mailing of the consent form
- Participation in another interventional study within the last 30 days
Where
- Pittsburgh, Pennsylvania
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Mar 25, 2026 · Source of record for eligibility and locations