As we age, maintaining muscle mass and strength becomes increasingly challenging. Sarcopenia—the progressive loss of skeletal muscle mass, strength, and function—affects millions of older adults and contributes to frailty, falls, reduced mobility, and lower quality of life. A key underlying issue is anabolic resistance: older muscles respond less robustly to the protein in our meals, requiring a stronger stimulus to trigger muscle protein synthesis (MPS), the process by which the body builds new muscle proteins.

Enter leucine, a branched-chain amino acid (BCAA) that acts as a powerful “on switch” for MPS via the mTOR signaling pathway. Research shows that leucine-enriched proteins (often from whey or specially formulated supplements) can help overcome anabolic resistance in older adults. Here’s what recent studies reveal—and what it means practically.

Why Older Adults Need More Leucine for Muscle Protein Synthesis

In younger people, consuming 20–25 g of high-quality protein (providing ~2–3 g of leucine) per meal maximally stimulates MPS. In older adults, the threshold is higher—often 35–40 g of protein or a leucine “boost” of 3–4 g per meal—because of blunted mTOR activation, slower amino acid absorption, and low-grade inflammation.

Leucine directly activates mTORC1, phosphorylating downstream targets like p70S6K1 and 4E-BP1 to ramp up protein translation. Studies dating back over a decade (and confirmed in free-living settings) show that adding leucine to meals can elevate integrated (multi-day) myofibrillar protein synthesis rates in older men, even when daily protein intake is at or slightly above the RDA (0.8 g/kg).

Spotlight on Recent Evidence: The 2023 Quasi-Experimental Study in Pre-Frail Older Adults

A 2023 study published in Frontiers in Medicine examined leucine-enriched protein supplementation in pre-frail older adults (age ~73 on average) who were consuming suboptimal protein (≤1 g/kg body weight/day).

Study design: 178 participants received either:

• Nutrition only: 16g extra protein + 3g leucine daily for 3 months (via specially formulated foods/beverages, often whey/soy-based), or
• Nutrition + exercise: the same supplement plus biweekly resistance, strength, and balance training sessions.

Key results at 3 months (compared to controls):

• Physical function improved significantly in the combined group: faster gait speed, better 5× sit-to-stand time, and higher Short Physical Performance Battery (SPPB) scores.
• Body composition gains: increases in fat-free mass index, appendicular skeletal muscle index (ASMI), and body cell mass—direct indicators of muscle preservation/growth.
• Inflammation dropped markedly: reductions in IL-6 and TNF-α (key drivers of muscle-wasting) in both supplemented groups.

Improvements were most pronounced when supplementation was paired with exercise, and benefits faded by 6 months once the intervention stopped—highlighting the need for ongoing habits.

Broader Picture from a 2025 Meta-Analysis

A July 2025 meta-analysis in Nutrients reviewed 17 randomized trials (including over 1,400 older adults with sarcopenia). It found:

• Trends toward better handgrip strength, appendicular muscle mass (normalized to height), and gait speed with leucine supplementation.
• Stronger effects with higher doses (>5.5g leucine/day) or when combined with vitamin D.
• Benefits were more consistent when leucine-enriched protein was paired with resistance training rather than used in isolation.

Some individual trials (e.g., leucine-rich whey + vitamin D) have shown clear gains in muscle mass and lower-extremity function, while others (including a 2026 Malaysian RCT in sarcopenic adults) found no significant changes in body composition or strength after 12 weeks of high-dose supplementation—though gene expression related to energy production and cell repair improved.

The takeaway? Leucine-enriched protein can meaningfully boost MPS and downstream outcomes in older adults, but results are strongest when:

• Combined with resistance exercise.
• Delivered in adequate doses (aim for 3+g leucine per main meal).
• Part of a higher overall protein intake (1.2–1.6g/kg/day recommended by many experts for older adults).

Why Consider a Leucine Supplement—and Why Xendurance's Strength-5 Stands Out

While food sources like whey, eggs, dairy, meat, and soy are excellent for leucine, many older adults find it challenging to hit the optimal 3–4g leucine threshold per meal through diet alone—especially if appetite is reduced, digestion is slower, or protein intake is inconsistent. A targeted leucine supplement offers convenience and precision: it delivers a potent, research-aligned dose without extra calories, carbs, or unwanted additives, making it easier to consistently overcome anabolic resistance and support MPS throughout the day.

One standout option is Xendurance's Strength-5, a leucine-infused amino acid blend designed specifically to combat age-related muscle decline while promoting growth, recovery, and overall vitality. Here's why it's a great enhancement to any diet:

• High leucine content in a complete EAA blend: It provides a solid dose of leucine (around 3g per serving based on reported amino profiles) alongside all nine essential amino acids, ensuring a full anabolic signal rather than leucine in isolation.
• Synergistic ingredients for extra muscle support: Includes 1g HMB per scoop (proven to reduce muscle breakdown and preserve lean mass, especially in older adults), 3g L-Glutamine (for repair, gut health, and immune function), and electrolytes for hydration and energy during activity.
• Advanced, plant-based innovation: Features Peptistrong®, an AI-powered peptide from fava beans that enhances the overall formula's effectiveness for muscle building and protection—ideal for those seeking clean, non-dairy alternatives.
• Targeted for healthy aging: Explicitly marketed to fight sarcopenia, minimize muscle loss, boost growth, and support vibrant aging—aligning perfectly with the needs of adults 60+ facing anabolic resistance.
• Easy integration: Mix one scoop into water or a shake (sip during workouts or add to meals), with clean, natural flavors and no unnecessary fillers.

Pairing Strength-5 with your regular meals can help ensure you consistently hit that critical leucine threshold, amplifying the benefits seen in studies on enriched supplementation.

Practical Takeaways for Older Adults

• Prioritize leucine-rich foods: Whey protein, dairy, eggs, beef, chicken, and soy are naturally high in leucine. A scoop of whey isolate often delivers 2.5–3g leucine.
• Consider targeted supplementation: Look for “leucine-enriched” or “leucine-fortified” whey/casein blends (many provide 3–6g leucine per serving). Some formulas also include vitamin D for synergy. Strength-5 is an excellent all-in-one choice for broader muscle support.
• Spread intake: Aim for 30–40g protein + ~3g leucine at each of 3–4 meals. Example breakfast: Greek yogurt + whey scoop or eggs + cheese.
• Pair with training: Even light resistance bands or bodyweight exercises 2–3 times weekly amplify the anabolic signal.
• Consult a professional: Especially if you have kidney issues or are on medications, though higher protein is generally safe and beneficial for healthy older adults.

From Anabolic Resistance to Real Results: How Leucine Can Help You Stay Strong

Leucine-enriched protein isn’t a miracle cure, but it’s one of the most evidence-based nutritional tools we have to fight anabolic resistance and support healthy aging. Recent studies confirm it can enhance muscle protein synthesis, preserve (or even build) muscle mass, improve function, and reduce inflammation—particularly when combined with exercise and consistent higher protein intake.

Adding a supplement like Xendurance's Strength-5 can make hitting those optimal leucine levels simpler and more effective, especially as part of a proactive strategy against sarcopenia. If you or a loved one is over 60 and noticing strength slipping, talk to a doctor or dietitian about incorporating leucine-rich strategies. Your muscles will thank you—and so will your independence and vitality in the years ahead.