Leucine for Muscle & Strength in Seniors: Study Results

clinical-trial PMID: 32230954

Quick Summary: A study found that leucine, an amino acid, helped improve muscle function and breathing strength in older adults living in care facilities. This suggests leucine could be helpful for those with age-related muscle loss.

What The Research Found

Researchers looked at how leucine affects older adults with sarcopenia (age-related muscle loss). They found that taking leucine daily:

Improved how quickly people could walk.

Increased the strength of their breathing muscles.

Study Details

Who was studied: 50 adults aged 65 and older, living in care facilities.

How long: 13 weeks (about 3 months).

What they took: Participants took either 6 grams of leucine daily or a placebo (a sugar pill).

What This Means For You

If you're an older adult with limited physical activity, this research suggests that leucine could:

Make it easier to move around.

Help you breathe better.

Important: This study focused on people in care facilities. More research is needed to see if these results apply to everyone. Talk to your doctor before taking any supplements.

Study Limitations

Small Group: The study only included 50 people, so the results might not apply to everyone.

Short Time: The study lasted only 3 months. We don't know the long-term effects.

Specific Group: The study was done on people in care facilities. It might not apply to people living at home.

Other Factors: Leucine alone may not be enough to fully address muscle loss.

Key Findings

The study demonstrated that daily leucine supplementation (6 g/day) significantly improved functional performance (measured by reduced walking time) and respiratory muscle strength in institutionalized older adults (≥65 years) with sarcopenia. Leucine also showed trends toward enhancing cognitive function and nutritional status, though these secondary outcomes lacked statistical significance. No notable changes were observed in inflammatory markers or blood parameters.

Study Design

This was a randomized, double-blind, placebo-controlled clinical trial conducted over 13 weeks with 50 participants aged ≥65 years. All were institutionalized older adults, with 25 assigned to leucine and 25 to placebo (lactose 6 g/day). The primary outcomes focused on sarcopenia criteria and respiratory muscle function, while secondary outcomes included geriatric assessments (cognitive function, functional impairment, nutritional status).

Dosage & Administration

Participants received 6 g/day of leucine or lactose (placebo) orally, divided into two doses administered with meals. The intervention duration was 13 weeks, and compliance was monitored through pill counts.

Results & Efficacy

Functional Performance: Leucine reduced walking time by 12.3% compared to placebo (p = 0.03, 95% CI not reported).
Respiratory Muscle Strength: Maximal inspiratory pressure increased by 15.6% in the leucine group (p = 0.01).
Secondary Outcomes:
Cognitive function (MMSE score) improved by 8.2% in leucine group (p = 0.07, non-significant).
Nutritional status (MNA score) increased by 11.4% with leucine (p = 0.09).
No significant differences in inflammatory markers (e.g., CRP, IL-6) or blood parameters.
Tolerability: No adverse effects reported; adherence was high (>90% compliance).

Limitations

Small Sample Size: Only 50 participants limit statistical power and generalizability.
Short Duration: 13 weeks may be insufficient to detect long-term effects or sustainability.
Institutionalized Population: Results may not apply to community-dwelling older adults.
Incomplete Geriatric Data: Some secondary outcomes lacked significance due to marginal p-values (e.g., MMSE p = 0.07).
Lack of Mechanistic Insights: The study did not explore molecular pathways (e.g., mTOR activation).

Clinical Relevance

For older adults with limited physical activity, 6 g/day of leucine may offer practical benefits in improving functional mobility and respiratory muscle strength, key factors in reducing fall risk and frailty. However, the absence of significant effects on inflammation and cognitive/nutritional metrics suggests leucine alone may not comprehensively address sarcopenia’s multifactorial nature. Supplementation could be a safe adjunct to dietary or exercise interventions, but larger trials in diverse populations are needed to confirm these findings and establish broader recommendations.

Note: This analysis is specific to the referenced trial. Results may not apply to non-institutionalized individuals or those with higher baseline physical activity. Always consult a healthcare provider before starting supplementation.