Protein Intake for Aging Muscle Growth

Overseen By Stuart M Phillips, PhD

Age: 65+

Sex: Any

Trial Phase: Academic

Sponsor: McMaster University

Must not be taking: Corticosteroids, Anabolic steroids

Disqualifiers: Cancer, Cardiovascular, Liver, others

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

Compensation: Varies

Number of Visits: 1

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores how different amounts and types of protein from plant-based or Lacto-vegetarian sources can help older adults maintain muscle mass. Muscle loss often occurs with age, making everyday tasks like climbing stairs or carrying groceries more difficult. The study aims to determine if consuming more protein, focusing on both quantity and quality, can combat this muscle loss. Suitable candidates for this trial are non-smokers aged 65 to 80 who are generally healthy and do not use assistive walking devices. As an unphased study, this trial offers a unique opportunity to contribute to research that could improve muscle health in older adults.

Will I have to stop taking my current medications?

The trial requires that you stop taking certain supplements and medications like corticosteroids, testosterone replacement therapy, anabolic steroids, creatine, whey protein, casein, or BCAAs at least 45 days before joining. If you're on any of these, you'll need to stop them to participate.

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

Research has shown that both Lacto-vegetarian and vegan diets can be safe and manageable for older adults if they include sufficient protein. One study suggested that consuming 1.2 to 1.5 grams of protein per kilogram of body weight daily is safe for healthy older individuals. This intake exceeds the usual recommended daily amount but remains safe.

For those on a vegan diet, consuming foods rich in protein and the amino acid lysine is crucial to ensure adequate protein intake. Studies have found no significant differences in muscle growth or strength when comparing soy and whey protein supplements, provided they contain similar amounts of leucine, an important amino acid for muscle health.

In summary, whether adhering to the usual protein amount or consuming slightly more, both Lacto-vegetarian and vegan diets are safe for older adults. Including enough high-protein foods is essential to meet dietary needs. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the Protein Intake for Aging Muscle Growth trial because it explores how different protein amounts and sources can optimize muscle growth in older adults. Unlike standard nutritional guidelines that often focus on animal-based protein sources, this trial examines plant-based proteins from lacto-vegetarian and vegan diets. By comparing the effects of consuming the Recommended Dietary Allowance (RDA) versus higher protein levels, researchers hope to uncover if plant-based diets can be just as effective, or even superior, in supporting muscle health as we age. This could lead to more sustainable and accessible dietary recommendations for muscle maintenance in older populations.

What evidence suggests that this trial's treatments could be effective for aging muscle growth?

This trial will compare different protein intake levels for aging muscle growth. Research has shown that increased protein consumption helps older adults maintain strong and healthy muscles. Studies suggest that consuming about 1.0 to 1.2 grams of protein per kilogram of body weight daily can preserve muscle and enhance muscle function. Illness may require a higher intake, around 1.2 to 1.5 grams per kilogram. Increased daily protein intake has been linked to small but significant improvements in muscle strength and size. Additionally, protein-rich supplements can boost muscle mass and strength over 12 weeks. These findings indicate that both the amount and type of protein consumed are crucial for maintaining muscle health with age. Participants in this trial will receive diets containing either the RDA or higher than the RDA for protein from Lacto-vegetarian and Vegan sources. ^{6 7 8 9 10}

Who Is on the Research Team?

Stuart Phillips, PhD

Principal Investigator

McMaster University, Department of Kinesiology

Are You a Good Fit for This Trial?

This trial is for men and women aged 65-80, in good health with a BMI of 20-35. Participants must be non-smokers, able to consent, and not use walking aids or have certain medical conditions like recent cancer (except some types), clotting disorders, severe illnesses affecting the study's integrity or taking specific supplements or steroids.

Inclusion Criteria

Be in general good health, non-smoking

Have a body mass index (BMI) between 20-35 kg/m2 (inclusive)

Be willing and able to provide informed consent

Exclusion Criteria

Excessive alcohol consumption (>21 units/week)

I have a condition causing significant weight loss, muscle loss, or weakness.

Hypersensitivity or known allergy to any of the components in the diets

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Dietary Intervention

Participants follow either a vegan or lacto-vegetarian diet to assess protein effects on muscle growth

2 weeks

Participants report to the lab for a day visit after two weeks on the diet

Metabolic Study

Participants undergo a tracer infusion-metabolic study to measure whole-body protein balance and dynamic proteome profiling

1 day

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after dietary intervention

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Protein quantity and quality

Trial Overview The study investigates how different amounts and types of protein affect muscle growth in older adults. It compares the effects of a plant-based diet versus a Lacto-vegetarian diet on maintaining muscle mass as people age.

How Is the Trial Designed?

Group I: RDA Lacto-Vegetarian/Vegan Experimental Treatment 1 Intervention

Subjects will receive diets containing the RDA for protein from Lacto-vegetarian and Vegan sources in different periods during the protocol.

Group II: Higher than RDA Lacto-Vegetarian/Vegan Experimental Treatment 1 Intervention

Subjects will receive diets containing more than the RDA for protein from Lacto-vegetarian and Vegan sources in different periods during the protocol.

Who Is Running the Clinical Trial?

McMaster University

Lead Sponsor

Trials

936

Recruited

2,630,000+

Dairy Farmers of Canada

Collaborator

Trials

33

Recruited

2,400+

National Dairy Council

Collaborator

Trials

20

Recruited

1,800+

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC4208946/

Protein intake and exercise for optimal muscle function with ... For healthy older adults, 1.0 to 1.2 g protein/kg body weight/day is recommended, with 1.2 to 1.5 g/kg for those with illnesses. Daily physical activity is ...

2. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC8978023/

Systematic review and meta‐analysis of protein intake to ... In conclusion, increasing daily protein ingestion results in small additional gains in LBM and lower body muscle strength gains in healthy adults enrolled in ...

3. sciencedirect.com sciencedirect.com/science/article/pii/S1279770725000314

Effectiveness of Protein-enriched oral nutritional ... This study evaluated the effects of protein-enriched oral nutritional supplementation (ONS) consumption for 12 weeks on muscle mass, muscular strength, and ...

4. frontiersin.org frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1547325/full

Role of protein intake in maintaining muscle mass ... Studies indicate that an intake of 1.0–1.2 g/kg body weight per day is more effective for preserving lean muscle mass, functional performance, ...

5. mdpi.com mdpi.com/2072-6643/17/15/2461

Protein and Aging: Practicalities and Practice For older adults, the literature suggests that a dietary protein intake of at least 1.0–1.2 g/kg/day is required in healthy, aging populations, and intakes of ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC6893534/

Dietary Protein and Amino Acids in Vegetarian Diets—A Review The median total protein intake in vegans was 71 g, amounting to 14.4% of energy intake [9], which was quite high when compared to other vegan populations, as ...

7. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC3926464/

Health effects of protein intake in healthy elderly populations Results from particularly prospective cohort studies suggest a safe intake of up to at least 1.2–1.5 g protein/kg BW/day or approximately 15–20 E%.

8. sciencedirect.com sciencedirect.com/science/article/pii/S0261561420306567

Intake and adequacy of the vegan diet. A systematic review ... This study aimed to investigate the adequacy of vegan diets in European populations and of their macro- and micronutrient intakes compared to World Health ...

9. mdpi.com mdpi.com/2072-6643/13/3/743

Protein Source and Muscle Health in Older Adults Research shows that higher dietary protein of up to 1.2 g/kgbodyweight/day may help prevent sarcopenia and maintain musculoskeletal health in older ...

10. sciencedirect.com sciencedirect.com/science/article/pii/S0022316624000397

The Importance of Dietary Protein Quality in Mid- to High- ... It is often overlooked that the “safe level of intake” (RDA) for protein recommended by the WHO, UNU, FAO [8] of 0.83 g/kg BW/d, refers to high quality protein ...