Soy vs Milk Protein for Healthy Nutrition

Not currently recruiting at 1 trial location

Overseen By Melanie Plourde, PhD

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of Guelph

Must not be taking: Omega-3, Lipid-lowering, Digestive

Disqualifiers: Diabetes, Cardiovascular, Neuropsychiatric, others

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

Compensation: Varies

Number of Visits: Unknown

Duration: 31 days

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to determine how milk and soy protein affect the body's production of omega-3 fatty acids, which are vital for heart and brain health. Researchers will compare the impact of milk or soy protein smoothies on omega-3 levels in the blood and assess how well the body absorbs and uses these fats. Healthy men and pre-menopausal women who can consume soy and dairy are suitable candidates for this study. Participants will drink two smoothies daily for 31 days, containing either milk protein isolate (MPI) or soy protein isolate (SPI), while avoiding the other type during the trial. As an unphased study, this trial provides participants with a unique opportunity to contribute to understanding the nutritional impact of common dietary proteins.

Will I have to stop taking my current medications?

If you are using omega-3 supplements, lipid-lowering, or digestive medications, you will need to stop taking them to participate in this trial.

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

Research shows that both soy protein isolate (SPI) and milk protein isolate (MPI) are generally safe to eat, but a few considerations are important.

Soy protein is often consumed and likely safe for up to six months. Some individuals might experience mild side effects like bloating, constipation, diarrhea, and nausea. Concerns about soy affecting hormones mainly relate to certain compounds in soy called isoflavones.

Milk protein is commonly used and usually well-tolerated. Handling the powder form might cause temporary eye irritation from dust. The main safety concern is for individuals with a milk allergy, as they might react to the proteins in milk. Otherwise, studies have not reported any major negative reactions to milk protein.

Overall, both proteins are generally safe, but personal allergies or dietary restrictions should be considered. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

Researchers are excited about these treatments because they explore how different protein sources, specifically soy and milk protein isolates, affect nutrition. Unlike standard dietary protein sources, which may include a mix of plant and animal proteins, these treatments use isolated proteins to precisely control and study their impact on health. Soy Protein Isolate (SPI) is plant-derived and excludes dairy, making it suitable for those with lactose intolerance or dairy allergies. On the other hand, Milk Protein Isolate (MPI) offers a complete amino acid profile typical of dairy, but without any soy, appealing to those who prefer animal-based proteins. By focusing on these isolated protein sources, researchers aim to uncover how each affects dietary health, potentially leading to more tailored nutritional recommendations.

What evidence suggests that this trial's treatments could be effective for omega-3 metabolism?

This trial will compare the effects of Soy Protein Isolate (SPI) and Milk Protein Isolate (MPI) on health. Research has shown that consuming soy protein, which participants in the SPI group will consume, can lower bad cholesterol (LDL) and might improve blood pressure, benefiting heart health. Soy protein may also aid in weight loss by increasing satiety. Meanwhile, milk protein, which participants in the MPI group will consume, has been found to enhance overall health, assist with weight and fat loss, improve body composition, and lower blood pressure. Both soy and milk proteins play a crucial role in maintaining a healthy and balanced body. ^{6 7 8 9 10}

Are You a Good Fit for This Trial?

This trial is for healthy adult men and pre-menopausal women who can eat soy and dairy products. Participants should be able to understand the study procedures and communicate with clinical staff.

Inclusion Criteria

You need to be able to eat soy and dairy products.

I am a healthy adult man or a pre-menopausal woman.

You need to be able to understand and talk to the doctors and nurses involved in the study.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants consume 2 smoothies per day containing either milk protein isolate or soy protein isolate for 31 days

31 days

Multiple visits for measurements on days 0, 15, 17, 19, 22, 24, 26, 29, 30, and 31

Follow-up

Participants are monitored for changes in EPA and DHA synthesis, fatty acid oxidation, and gene expression after the treatment phase

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Milk Protein Isolate (MPI)
• Soy Protein Isolate (SPI)

Trial Overview

The study is testing whether milk protein (MPI) or soy protein (SPI) affects how our bodies handle omega-3 fatty acids, which are important for health. It will look at blood levels of EPA and DHA, their synthesis, fat oxidation, and absorption from the gut.

How Is the Trial Designed?

Group I: Soy Protein Isolate (SPI) Experimental Treatment 1 Intervention

Study participants in the SPI group will consume 2 smoothies per day for 31 days, where each smoothie provides 300 kcal in total, composed of 45% from carbohydrate (maltodextrin), 20% from protein (soy protein isolate) and 35% from fat (a blend of flaxseed, safflower, and coconut oils). Each smoothie will be mixed with water up to volume of 250mL. Individuals in this group will not consume dairy-containing beverages and foods during the 31-day study.

Group II: Milk Protein Isolate (MPI) Experimental Treatment 1 Intervention

Study participants in the MPI group will consume 2 smoothies per day for 31 days, where each smoothie provides 300 kcal in total, composed of 45% from carbohydrate (maltodextrin), 20% from protein (milk protein isolate) and 35% from fat (a blend of flaxseed, safflower, and coconut oils). Each smoothie will be mixed with water up to volume of 250mL. Individuals in this group will not consume soy-containing beverages and foods during the 31-day study.

Who Is Running the Clinical Trial?

University of Guelph

Lead Sponsor

Trials

87

Recruited

15,100+

Université de Sherbrooke

Collaborator

Trials

317

Recruited

79,300+

Published Research Related to This Trial

Partial replacement of soy protein isolate (SPI) with okara dietary fiber (ODF) enhances the gelling properties of SPI gels, improving their hardness and texture, especially in varying salt concentrations.

The study found that ODF reduces SPI's self-aggregation and increases disulfide bond formation, which contributes to better gel quality and higher dietary fiber content in the final product.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Gel properties of okara dietary fiber-fortified soy protein isolate gel with/without NaCl. Lv, Y., Wang, J., Xu, L., et al.[2022]

In a study involving male Sprague-Dawley rats, both isolated proteins (dairy whey and soy) and protein blends enhanced muscle protein synthesis (MPS) after meals, indicating their effectiveness in promoting muscle growth.

Blend 2, which contained a specific ratio of whey, caseinate, and soy, showed a significantly higher peak in muscle protein synthesis compared to whey protein alone at 135 minutes post-meal, suggesting that certain protein blends may be more beneficial for muscle recovery.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A soy, whey and caseinate blend extends postprandial skeletal muscle protein synthesis in rats. Butteiger, DN., Cope, M., Liu, P., et al.[2021]

In a study of 43 patients with suspected milk- and/or soy-protein enterocolitis, both powdered and liquid soybean formulas elicited similar rates of adverse reactions, with 33% reacting to powdered soy and 30% to liquid soy.

The findings suggest that many patients with milk protein enterocolitis also have soy protein enterocolitis, and that the order of food challenges may influence reaction rates, indicating a potential local immune response to the protein isolates.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Prospective oral food challenge study of two soybean protein isolates in patients with possible milk or soy protein enterocolitis. Burks, AW., Casteel, HB., Fiedorek, SC., et al.[2023]

Citations

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Milk protein for improved metabolic health - PubMed Central

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Prolonged or repeated exposure to dust generated by this product may cause irritation to skin, eyes and respiratory system. This product.

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Agency Response Letter GRAS Notice No. GRN 000633

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