Protein Shakes for Nutrient Response

Overseen By Babak Razani, MD-PhD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of Pittsburgh

Must not be taking: Anti-inflammatory, Immunomodulatory, Lipid-lowering

Disqualifiers: Cardiovascular disease, Diabetes, Autoimmune, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 3

Duration: 4 weeks

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to determine how different types of protein in smoothies affect metabolism and the immune system in healthy adults. Researchers want to know if animal-based and plant-based protein smoothies, with or without added leucine (an amino acid), alter amino acid levels and metabolic pathways like mTOR, which relates to heart health. Participants will consume various protein smoothies, and their blood will be tested to assess the effects. Individuals who are generally healthy, not on special diets, and willing to adhere to study guidelines may be suitable for this trial. As an unphased trial, this study provides a unique opportunity to advance scientific understanding of nutrition and health.

Will I have to stop taking my current medications?

The trial does not specify if you need to stop taking your current medications, but you cannot participate if you are actively using anti-inflammatory, immunomodulatory, or lipid-lowering medications.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

A previous study found that protein powders, whether animal- or plant-based, contained varying levels of heavy metals like lead and cadmium. These metals were often higher in plant-based products. Despite this, occasional use of these protein powders is generally considered safe, while frequent use can be harmful.

Adding leucine, an amino acid, to plant-based protein smoothies makes them comparable to animal-based ones without introducing additional safety risks beyond those already present in the protein powders.

Overall, while these protein shakes are usually safe, it is important to be aware of the potential heavy metal content. Participants should consider their health and exposure to these metals before joining the trial. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about these protein smoothies because they explore different sources and enhancements of protein intake, which could offer new insights into nutrient absorption and metabolism. Unlike traditional protein supplements, which often focus on a single protein source, these smoothies compare animal-based proteins with plant-based options, including a version enhanced with leucine, an amino acid that may boost muscle protein synthesis. This trial could reveal how different protein types and enhancements affect the body's nutrient response, potentially leading to more tailored and effective dietary recommendations.

What evidence suggests that this trial's treatments could be effective?

This trial will compare different protein smoothies to assess their effects on nutrient response. Research has shown that animal-based proteins generally support muscle growth in younger adults more effectively than plant-based proteins. Animal proteins typically contain more essential building blocks, such as leucine, which aid in muscle growth and repair.

Conversely, plant-based proteins offer their own benefits. They are often rich in fiber and natural compounds that can reduce inflammation and improve overall health. Some studies suggest that increased consumption of plant-based foods is linked to better health outcomes.

In this trial, one treatment arm will include a plant-based protein smoothie with added leucine. Adding leucine to plant-based proteins may help them function like animal proteins in boosting metabolism and the immune system. This combination could provide the muscle-building benefits of animal proteins while retaining the health advantages of plant proteins. ^{6 7 8 9 10}

Who Is on the Research Team?

Babak Razani, MD-PhD

Principal Investigator

University of Pittsburgh

Are You a Good Fit for This Trial?

This trial is for healthy adults who may be at risk of metabolic syndrome or stroke. Participants must attend three clinic visits, consume different protein smoothies, and provide blood samples. Specific inclusion or exclusion criteria are not provided.

Inclusion Criteria

Not currently following a prescribed or restrictive diet (for example, vegan, ketogenic or high-protein regimen) or regularly taking high-protein supplements

BMI 18.5-29.9 kg/m²

Willing to comply with dietary restrictions and study procedures

Exclusion Criteria

I have kidney or liver problems.

Pregnancy or breastfeeding

Participation in another interventional study within the last 30 days

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants consume different protein smoothies and provide blood samples to assess metabolic and immune responses

4 weeks

3 visits (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Animal-Based Protein Smoothie
• Plant-Based Protein Smoothie
• Plant-Based Protein Smoothie with Leucine

Trial Overview The study compares the effects of animal-based protein smoothies to two types of plant-based ones (with and without added leucine) on metabolism and immune response, focusing on amino acid levels in the blood and the mTOR pathway related to nutrient use.

How Is the Trial Designed?

Group I: Plant-Based → Plant-Based with Leucine → Animal-Based Experimental Treatment 3 Interventions

Participants in this arm will receive the plant-based protein smoothie first, the plant-based protein smoothie with leucine second, and the animal-based protein smoothie third. All clinical procedures are the same across visits.

Group II: Plant-Based with Leucine → Animal-Based → Plant-Based Experimental Treatment 3 Interventions

Participants in this arm will receive the plant-based protein smoothie with leucine at their first visit, the animal-based smoothie second, and the plant-based protein smoothie third. The same procedures will be followed at each visit.

Group III: Animal → Plant → Plant+Leucine Experimental Treatment 3 Interventions

Participants in this arm will receive the animal-based protein smoothie during their first visit, the plant-based protein smoothie during their second visit, and the plant-based protein smoothie with added leucine during their third visit. All study visits follow the same protocol, including fasting, blood draws, and postprandial assessments.

Who Is Running the Clinical Trial?

University of Pittsburgh

Lead Sponsor

Trials

1,820

Recruited

16,360,000+

Citations

1. clinicaltrials.gov clinicaltrials.gov/study/NCT07121010

How Animal and Plant Protein Shakes Change the Body's ... The findings from this study could provide novel insights into how different dietary proteins modulate nutrient sensing and immune pathways.

2. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC7926405/

Animal Protein versus Plant Protein in Supporting Lean ... Collectively, animal protein tends to be more beneficial for lean mass than plant protein, especially in younger adults.

3. frontiersin.org frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2024.1412182/full

Impacts of dietary animal and plant protein on weight and ... Altogether, there is, therefore, no compelling evidence that a particular protein source leads to greater weight loss, or improvement in glycemia, than another, ...

4. webmd.com webmd.com/diet/protein-shakes

Protein Shakes: Which One Do You Need? Plant-based proteins, like pea, soy, hemp, and rice, tend to have more fiber and less fat than animal-based protein powders.

5. sciencedirect.com sciencedirect.com/science/article/pii/S002231662210667X

A Systematic Review of the Effects of Plant Compared with ... The aim of the current systematic review was to compare the impact of plant- and animal-sourced dietary proteins on several features of metabolic syndrome in ...

6. consumerreports.org consumerreports.org/lead/protein-powders-and-shakes-contain-high-levels-of-lead-a4206364640/

Protein Powders and Shakes Contain High Levels of Lead CR tests of 23 popular protein powders and shakes found that most contain high levels of lead.

7. foodandwine.com foodandwine.com/protein-powder-heavy-metals-contamination-consumer-reports-investigation-11828759

Consumer Reports Finds High Levels of Lead in Protein ... A Consumer Reports investigation found that more than two-thirds of tested protein powders and shakes contained more lead per serving than ...

8. today.com today.com/health/diet-fitness/lead-in-protein-powder-rcna236940

Some Protein Powders Contain High Lead Levels, New ... Twelve powders contained elevated but relatively lower levels of lead, which Consumer Reports says are safe to consume "occasionally" — anywhere ...

9. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC7509468/

A human health risk assessment of heavy metal ingestion ... Protein powder supplements may contain detectable levels of heavy metals. •. Plant based protein powder supplements tend to have a higher heavy metal burden ...

10. npr.org npr.org/2025/10/16/nx-s1-5576294/protein-powder-lead-consumer-reports

Consumer Reports finds lead in popular protein powders Consumer Reports expressed concern about high levels of lead in some two dozen protein powders, but only with repeated high exposure.