How Animal and Plant Protein Shakes Change the Body's Nutrient and Health Responses
Randomized Crossover Trial of Protein Source and Leucine Supplementation on Metabolic and Immune Signaling Pathways
University of Pittsburgh
20 participants
Mar 24, 2026
INTERVENTIONAL
Conditions
Summary
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.
Eligibility
Inclusion Criteria5
- 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 Criteria6
- 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
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Interventions
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.
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.
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.
Locations(1)
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NCT07121010