Protein Quantity and Quality in Older Subjects

Overview

After the age of ~50, humans start to lose muscle mass at a rate of about 1-3% per year. However, the loss of muscle mass beyond a certain point can make it increasingly difficult to perform activities of daily living such as rising from a chair, going up and downstairs, carrying groceries, etc. A reason why muscle mass is lost with age is that skeletal muscles become less sensitive to the growth-promoting effects of physical activity and protein ingestion. This loss of sensitivity can be overcome by consuming larger amounts of protein; however, many older adults have difficulties simply consuming greater amounts of protein from whole-food sources. Therefore, the research in this study aims to investigate how different amounts and types of protein, of either a 100%-plant-based or Lacto-vegetarian (plant-based plus dairy) protein sources, affect muscle growth. This information will be important when providing information to older adults about the amount and type of protein that should be consumed by older adults to help prevent the loss of muscle mass that typically occurs with advancing age.

Eligibility

Inclusion Criteria:

1. Be a male or female, between the ages of 65 - 80 years (inclusive)
2. Be willing and able to provide informed consent
3. Be in general good health, non-smoking
4. Have a body mass index (BMI) between 20-35 kg/m2 (inclusive)

Exclusion Criteria:

1. Use of tobacco or related products.
2. Any concurrent medical, orthopedic, or psychiatric condition that, in the opinion of the Investigator, would compromise his/her ability to comply with the study requirements.
3. Use assistive walking devices (e.g., cane or walker)
4. History of cancer within the last 5 years, except basal cell carcinoma, non-squamous skin carcinoma, prostate cancer or carcinoma in situ with no significant progression over the past 2 years.
5. Significant orthopedic, cardiovascular, pulmonary, renal, liver, infectious disease, immune disorder, or metabolic/endocrine disorders or other disease that would preclude oral protein supplement ingestion and/or assessment of safety and study objectives.
6. Any cachexia-related condition (e.g., relating to cancer, tuberculosis or human immunodeficiency virus infection and acquired immune deficiency syndrome) or any genetic muscle diseases or disorders
7. Current illnesses which could interfere with the study (e.g. prolonged severe diarrhea, regurgitation, difficulty swallowing)
8. Hypersensitivity or known allergy to any of the components in the diets.
9. Excessive alcohol consumption (>21 units/week)
10. History of bleeding diathesis, platelet or coagulation disorders, or antiplatelet/anticoagulation therapy (up to 81mg of baby aspirin per day taken as a prophylactic is permitted).
11. History of statin myalgia.
12. Personal or family history of a clotting disorder or deep vein thrombosis;
13. Concomitant use of corticosteroids, testosterone replacement therapy (ingestion, injection, or transdermal), any anabolic steroid, creatine, whey protein supplements, casein, or branched-chain amino acids (BCAAs) within 45 days prior to screening.