Leucine Co-ingestion and Myofibrillar Protein Synthesis in Older Adults

NCT02371278 | Completed

• 1 other identifier: LEU-MEALS-2015
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

The loss of muscle mass with aging is associated with a dysregulation of muscle protein synthesis (MPS) that is generally characterized by a suppressed MPS response to protein ingestion. This 'anabolic resistance' to protein feeding can be overcome with the ingestion of larger protein servings (\~0.4g/kg/meal, equivalent to \~ 30 - 40g/meal); however, older adults would likely find it challenging to consume such quantities of protein on a per meal basis. The amino acid leucine has a unique role as a key 'activator' of MPS. Some research shows that increasing the leucine content of a suboptimal dose of a protein supplement can enhance the MPS response in older adults. However it is currently unknown whether the co-ingestion of leucine with normal, mixed meals can increase MPS. Furthermore, it has been suggested that leucine supplementation may only benefit older adults consuming suboptimal daily protein intakes. Therefore, the purpose of the current study is to examine the impact of leucine co-ingestion with mixed macronutrient meals on the myofibrillar protein synthetic response in older men consuming daily protein intakes at or below the current recommendations. A further objective is to determine whether the myofibrillar protein synthetic response to a session of resistance exercise is enhanced by leucine supplementation with meals. The investigators hypothesize that, in both the exercised and non-exercised condition, leucine co-ingestion at meals will enhance integrative myofibrillar protein synthesis in older adults consuming lower daily protein intakes, but will not augment MPS in those consuming higher daily protein. The investigators further hypothesize that the influence of leucine supplementation on MPS will be greater in the exercise condition than the non-exercise condition.

Conditions

Aging; Sarcopenia

Keywords

Leucine; Protein; Diet; Muscle protein synthesis

Outcome Measures

Primary Outcomes (1)

• Myofibrillar protein fractional synthetic rate

  The incorporation of a stable isotope (deuterium) into muscle tissue will allow for the determination of fractional synthetic rate, which is indicative of muscle protein synthesis.

  3 days

Secondary Outcomes (3)

• Aminoacidemia in response to daily meals with and without leucine supplementation

  3 days

• Glycaemia in response to daily meals with and without leucine supplementation

  3 days

• Insulinemia in response to daily meals with and without leucine supplementation

  3 days

Study Arms (2)

Higher daily protein

OTHER

Diets will provide protein intakes of 1.2 g/kg/d. Placebo with meals for 3 days, and leucine with meals for 3 days.

Dietary Supplement: Leucine; Dietary Supplement: Placebo

Lower daily protein

OTHER

Diets will provide protein intakes of 0.8 g/kg/d. Placebo with meals for 3 days, and leucine with meals for 3 days.

Dietary Supplement: Leucine; Dietary Supplement: Placebo

Interventions

Leucine DIETARY_SUPPLEMENT

5 g leucine with sucrose and maltodextrin

Higher daily protein; Lower daily protein

Placebo DIETARY_SUPPLEMENT

5 g glycine with sucrose and maltodextrin

Higher daily protein; Lower daily protein

Eligibility Criteria

• Age: 65 Years - 85 Years
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Older Adult (65+)

You may qualify if:

• Body mass index (BMI) between 20-35 kg/m2
• Non-smokers

You may not qualify if:

• Diabetes mellitus, prediabetes and the metabolic syndrome
• Cardiovascular disease
• Neuromuscular problems or muscle wasting diseases
• Renal disease
• Gastrointestinal disease
• Musculoskeletal conditions such as rheumatoid arthritis or osteoarthritis
• Infectious disease
• Cancer
• Significant body mass loss in the 1 month period prior to the study
• Vegetarianism
• Use of medications known to interfere with muscle metabolism (i.e. beta-blockers, high dose non-steroidal anti-inflammatory drugs, corticosteroids, hormone replacement therapy, antiarrhythmic drugs, warfarin, prescription strength acne medications, oral hypoglycaemic agents and insulin)
• Regular resistance training or daily step counts \>9,000 or \<3,500

Sponsors & Collaborators

• McMaster University: lead
• Canadian Institutes of Health Research (CIHR): collaborator

Study Sites (1)

McMaster University

Hamilton, Ontario, L8S 4K1, Canada

Location

Related Publications (1)

• Murphy CH, Saddler NI, Devries MC, McGlory C, Baker SK, Phillips SM. Leucine supplementation enhances integrative myofibrillar protein synthesis in free-living older men consuming lower- and higher-protein diets: a parallel-group crossover study. Am J Clin Nutr. 2016 Dec;104(6):1594-1606. doi: 10.3945/ajcn.116.136424. Epub 2016 Nov 9.

  PMID: 27935521 DERIVED

MeSH Terms

Conditions

Sarcopenia

Interventions

Leucine

Condition Hierarchy (Ancestors)

Muscular Atrophy; Neuromuscular Manifestations; Neurologic Manifestations; Nervous System Diseases; Atrophy; Pathological Conditions, Anatomical; Pathological Conditions, Signs and Symptoms; Signs and Symptoms

Intervention Hierarchy (Ancestors)

Amino Acids, Branched-Chain; Amino Acids; Amino Acids, Peptides, and Proteins; Amino Acids, Essential

Study Officials

• Stuart M Phillips, PhD

  McMaster University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor Stuart M. Phillips, Ph.D. FACN, FACSM

Study Record Dates

• First Submitted: February 13, 2015
• First Posted: February 25, 2015
• Study Start: May 1, 2015
• Primary Completion: October 1, 2015
• Study Completion: October 1, 2015
• Last Updated: March 16, 2016

Record last verified: 2016-03

Locations

CA (1)