Animal versus plant protein smoothies and their effects on metabolism and immune signaling

Randomized Crossover Trial of Protein Source and Leucine Supplementation on Metabolic and Immune Signaling Pathways

This trial will test whether drinking animal-based, plant-based, or plant-based plus leucine protein smoothies changes blood amino acids and metabolic and immune responses in healthy adults.

Quick facts

• Phase: NA
• Study type: Interventional
• Enrollment: 20 (estimated)
• Ages: 18 Years to 65 Years
• Sex: All
• Sponsor: University of Pittsburgh (other)
• Locations: 1 site (Pittsburgh, Pennsylvania)
• Trial ID: NCT07121010 on ClinicalTrials.gov

What this trial studies

This randomized, controlled, crossover trial has healthy adults come for three clinic visits where they drink a high-protein smoothie: one animal-based, one plant-based, and one plant-based with added leucine. Blood samples are taken before and at 1 and 3 hours after each smoothie to measure circulating amino acids and downstream metabolic and immune signaling pathways, including mTOR-related markers. The within-subject crossover design lets researchers compare acute responses to each protein condition in the same participants. All smoothies are prepared to meet Halal and Kosher dietary guidelines and the study is conducted at the University of Pittsburgh CTRC.

Who should consider this trial

Good fit: Ideal candidates are generally healthy adults aged 18–65 with BMI 18.5–29.9 kg/m² who are not on chronic medications or restrictive diets and can attend three in-person clinic visits in Pittsburgh.

Not a fit: Patients with cardiovascular disease, diabetes, autoimmune disorders, significant kidney or liver dysfunction, pregnancy or breastfeeding, those on immunomodulatory or lipid‑lowering medications, or people following restrictive diets are unlikely to benefit from participating.

Why it matters

Potential benefit: If successful, the findings could help tailor dietary protein recommendations to reduce cardiometabolic risk by showing how protein type and leucine affect metabolic and immune pathways.

How similar studies have performed: Prior research shows leucine-rich animal proteins raise circulating branched-chain amino acids and can activate mTOR signaling, but randomized crossover tests directly comparing plant versus animal smoothies with added leucine in healthy adults are limited.

Eligibility criteria

Inclusion Criteria:

1. Age 18-65 years
2. BMI 18.5-29.9 kg/m²
3. Generally healthy, without known chronic illness and/or treatment with chronic medications
4. Willing to comply with dietary restrictions and study procedures
5. Not currently following a prescribed or restrictive diet (for example, vegan, ketogenic or high-protein regimen) or regularly taking high-protein supplements

Exclusion Criteria:

1. History of cardiovascular disease, diabetes, or autoimmune disorders
2. Active use of anti-inflammatory, immunomodulatory, or lipid-lowering medications
3. Renal or hepatic dysfunction
4. Pregnancy or breastfeeding
5. 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
6. Participation in another interventional study within the last 30 days

Where this trial is running

Pittsburgh, Pennsylvania

• UPMC Montefiore - Clinical and Translational Research Center (CTRC) — Pittsburgh, Pennsylvania, United States (RECRUITING)

Study contacts

• Study coordinator: Ali Ajam, MD

Conditions: Cardiometabolic Health, mTOR Signaling, Dietary Protein, Cardiometabolic Disease, Atherosclerosis, Nutrient Signaling