Leucine acts as a metabolic “on-switch” for muscle by activating the mTOR pathway, which drives muscle protein synthesis. As we age, muscles become resistant to this signal, requiring higher leucine intake to trigger repair and growth. Clinical evidence shows that meeting a per-meal leucine threshold can significantly improve muscle strength and function, making it a key nutritional strategy against Sarcopenia.

Who benefits most from leucine optimization?

• Adults over 50 with declining strength

• Individuals with low protein intake

• Patients with sarcopenia or frailty

• Those undergoing weight loss

• Plant-based individuals at risk of low leucine intake

What is the best leucine intake for sarcopenia?

• Older adults need 2.5–3 g leucine per meal to stimulate muscle protein synthesis

• Total daily intake: 6–9 g leucine

• Best strategy: 25–30 g high-quality protein per meal

• Most effective when combined with resistance training

• In frail adults: 6 g/day leucine improves walking speed and respiratory strength

Clinician’s Perspective: Translating Leucine Science into Practice

From a clinical standpoint, leucine represents one of the most targeted nutritional interventions available for the prevention and management of Sarcopenia. Its unique ability to activate the mTOR pathway—the central regulator of muscle protein synthesis (MPS)—places it at the intersection of molecular biology and functional medicine. However, the key clinical challenge is not leucine deficiency per se, but anabolic resistance, a well-documented phenomenon in aging muscle that blunts responsiveness to dietary protein (Katsanos et al., 2006).

This has direct implications for dietary prescription. Traditional protein recommendations based solely on total daily intake are insufficient in older adults. Instead, clinicians should emphasize per-meal leucine thresholds (2.5–3 g) to reliably stimulate MPS, typically achieved through 25–30 g of high-quality protein (Ijaz et al., 2025). This “threshold concept” is arguably more important than total protein intake alone and should guide meal structuring in both ambulatory and institutionalized patients.

Evidence from randomized trials further supports leucine’s role beyond theoretical physiology. In frail, non-exercising populations, 6 g/day leucine supplementation improved gait speed and respiratory muscle strength, highlighting its utility even in patients unable to perform resistance training (Martínez-Arnau et al., 2020). However, outcomes are consistently superior when leucine is combined with resistance exercise and adequate vitamin D status, underscoring the importance of a multimodal intervention strategy (Guo et al., 2022).

Emerging data also suggest inter-individual variability in response, potentially mediated by gut-derived metabolites such as trimethylamine, opening the door to precision nutrition approaches in sarcopenia care (Tang et al., 2026).

In practice, leucine should not be viewed as a standalone supplement, but as a strategic nutritional signal—one that must be delivered in the right dose, distribution, and physiological context to preserve muscle mass, maintain functional independence, and mitigate the trajectory of age-related decline.

Understanding Sarcopenia: The Silent Muscle Thief

Sarcopenia is the progressive, age-related loss of skeletal muscle mass, strength, and function. Beginning around age 30, humans lose approximately 3–8% of their muscle mass per decade. After the age of 60, that rate accelerates considerably.

The consequences reach far beyond physical appearance. Sarcopenia is directly linked to increased fall risk and fractures, loss of independence in daily activities, slower metabolism and greater fat accumulation, reduced bone density, higher risk of chronic disease, and in older adults, even respiratory complications.

What makes sarcopenia particularly insidious is that it develops quietly over years and decades before most people notice. By the time weakness or difficulty climbing stairs becomes apparent, significant muscle loss has typically already occurred.

The biological mechanism underlying much of this decline is a phenomenon called anabolic resistance—a blunting of the muscle's ability to respond to the signals that normally trigger growth and repair. As you age, your muscles effectively become "hard of hearing" when leucine knocks on the door.

This is exactly where targeted leucine supplementation becomes clinically meaningful.

The Leucine Threshold: Why Older Adults Need More

A landmark study by Katsanos et al. (2006) established something crucial: older adults require a significantly higher proportion of leucine within their protein intake to stimulate the same level of muscle protein synthesis that younger individuals achieve with less. In practical terms, older adults need approximately 50% more leucine per meal than their younger counterparts to overcome anabolic resistance and trigger meaningful MPS.

This finding has since shaped the entire framework of nutritional recommendations for sarcopenia. It explains why many older adults eat what appears to be "enough protein" yet continue to lose muscle—their meals simply do not deliver a sufficient leucine dose to clear the activation threshold.

Current evidence points to a leucine threshold of 2.5–3 grams per meal for adults over 60, achievable through approximately 25–30 grams of high-quality protein per eating occasion.

What the Latest Research Actually Shows

Ijaz et al. (2025) — Leucine-Enriched Whey Protein and Resistance Training

A comprehensive systematic review published in the Journal of Cachexia, Sarcopenia and Muscle analysed multiple randomised controlled trials examining leucine-enriched whey protein supplementation in older sarcopenic adults (Ijaz et al., 2025). The findings were striking in their consistency.

When leucine-enriched whey protein was combined with resistance training, participants achieved superior improvements in lean muscle mass, muscle strength, and overall physical performance compared to either intervention alone. The review identified whey protein sources delivering approximately 2.3 g of leucine per serving as particularly effective, owing to whey's rapid absorption kinetics and its complete essential amino acid profile.

The review supports a daily protein target of 1.0–1.2 g per kilogram of body weight, with each meal delivering 25–30 g of leucine-rich protein. For someone weighing 70 kg, that translates to approximately 70–84 g of protein daily, distributed across meals rather than front-loaded into one sitting.

Practical takeaway: If you can engage in resistance exercise, pairing leucine-enriched whey protein with strength training offers the most robust nutritional strategy for sarcopenia currently supported by evidence.

Martínez-Arnau et al. (2020) — Leucine Alone, Without Exercise

One of the most clinically important studies for the many older adults who cannot perform vigorous exercise is the randomised, double-blind, placebo-controlled trial by Martínez-Arnau et al. (2020), published in Nutrients.

Fifty institutionalised adults aged 65 and over—many of them frail and with limited exercise capacity—received either 6 grams of pure leucine daily or a lactose placebo for 13 weeks. The results challenged the assumption that leucine only "works" in combination with exercise.

The leucine group demonstrated significantly improved walking speed (p = 0.011), meaningful changes in lean mass index, and—perhaps most surprisingly—significant improvements in respiratory muscle strength, specifically maximum static expiratory force (p = 0.026). This is clinically significant: respiratory muscle weakness in older adults is associated with pneumonia, reduced ventilatory capacity, and hospitalisation.

Leucine was well-tolerated throughout, with no significant adverse effects reported.

Practical takeaway: For frail, mobility-limited, or institutionalised older adults, 6 g of daily leucine supplementation offers a safe, accessible path to improved functional mobility and respiratory health—even without structured exercise.

Huang & Hsieh (2025) — Meta-Analysis Confirms Functional Benefits

A 2025 meta-analysis published in Nutrients by Huang and Hsieh synthesised data from multiple randomised controlled trials examining leucine supplementation specifically in older adults diagnosed with sarcopenia. The analysis confirmed meaningful improvements in functional performance outcomes including gait speed and physical performance scores, reinforcing the cumulative evidence that leucine-targeted nutrition produces real-world functional gains—not just lab-measured changes in protein synthesis.

Guo et al. (2022) — Leucine Alone vs. Leucine in Combination

Across 17 randomised trials, Guo et al. (2022) found that leucine supplementation administered in isolation showed more modest effects on muscle mass and strength than leucine delivered as part of enriched protein formulas. However, when leucine was combined with vitamin D, improvements in handgrip strength and gait speed were more pronounced.

This finding has important practical implications: leucine works best as part of a complete nutritional strategy, not as a standalone fix. Vitamin D adequacy, total protein sufficiency, and caloric balance all modulate how effectively leucine translates into muscle gains.

Tang et al. (2026) — A Critical New Finding on Non-Responders

A fascinating 2026 study published in npj Aging by Tang and colleagues identified why some older adults fail to respond to leucine-enriched protein supplementation as expected. Elevated levels of trimethylamine (TMA)—a gut microbiome metabolite—were found to characterise individuals whose muscle mass did not improve despite adequate leucine intake (Tang et al., 2026).

This research opens an entirely new avenue for personalised nutrition in sarcopenia management, suggesting that gut microbiome health may need to be addressed alongside leucine supplementation for optimal outcomes in certain individuals.

Lin et al. (2026) — Leucine, Citrulline, and Vascular-Muscle Crosstalk

A 2026 review in Frontiers in Nutrition by Lin and colleagues highlighted the integrative roles of leucine, L-citrulline, and exercise in targeting the muscle-vasculature interface during aging (Lin et al., 2026). The review found that leucine's anabolic effects on muscle are enhanced when vascular function is simultaneously supported, as healthy blood flow amplifies nutrient delivery to muscle tissue. This adds further rationale for combining leucine supplementation with aerobic activity and adequate hydration.

How Much Leucine Do You Need? Evidence-Based Dosing

Based on the cumulative weight of clinical evidence, here are the practical recommendations:

For Adults Over 60:

• Minimum per meal: 2.5–3 g of leucine

• Optimal daily total: 6–9 g, distributed across three meals

• Post-exercise window: 3–4 g within 30–60 minutes of resistance training

• Without exercise: 6 g daily has demonstrated functional benefits

For Adults Aged 40–60:

• Minimum per meal: 2 g of leucine

• Daily total: 6–8 g

Distribution matters enormously. Consuming all your leucine in one meal is far less effective than spreading it across three separate eating occasions, each independently hitting the mTOR activation threshold. Think of it as lighting three fires throughout the day rather than one large bonfire.

Best Food Sources of Leucine

You do not necessarily need supplements to meet leucine targets. Many whole foods deliver meaningful amounts:

Animal-Based Sources (per 100 g):

• Whey protein concentrate: 10–12 g per scoop

• Chicken breast: 2.5 g

• Soybeans: 2.6 g

• Pumpkin seeds: 2.4 g

• Lamb: 1.7 g

• Salmon: 1.6 g

• Greek yogurt: 1.3 g

• Eggs: 1.0 g

Plant-Based Sources (per 100 g):

• Lentils: 1.8 g

• Peanuts: 1.7 g

• Chickpeas: 1.4 g

Plant-based proteins can absolutely contribute to leucine targets, though they typically require larger serving sizes to match the leucine density of animal sources. A strategic combination of legumes, seeds, and whole grains throughout the day helps meet needs effectively. Where meeting targets through food alone proves difficult—due to appetite loss, dietary restrictions, or elevated age-related requirements—supplementation is a sensible and evidence-supported strategy.

Also Read: Leucine Foods Chart: Exactly How Much You Need Per Meal for Muscle Growth | DR T S DIDWAL

When Supplementation Makes Sense

Consider leucine supplements if you:

• Are over 60 and struggling to consistently meet leucine targets through food

• Follow a plant-based diet and are concerned about leucine adequacy

• Are undergoing intentional caloric restriction for weight loss

• Engage in regular resistance training and want to optimise recovery

• Have reduced appetite or difficulty consuming large meals

• Are frail, institutionalised, or have limited mobility

Supplement options include:

• Pure leucine powder (6 g daily, as used in the Martínez-Arnau trial)

• Leucine-enriched whey protein (~2.3 g leucine per serving, as highlighted in Ijaz et al.)

• Branched-chain amino acids (BCAAs): leucine combined with isoleucine and valine

• Essential amino acids (EAAs): all nine essential amino acids including leucine

Safety note: Leucine supplementation is well-tolerated at 6–9 g daily in healthy adults. Those with maple syrup urine disease or significant kidney disease should discuss protein and amino acid intake with their healthcare provider before supplementing.

The Anabolic Blueprint: A High-Leucine Daily Menu

Optimized for Muscle Protein Synthesis (MPS) in Older Adults (75 kg Target)

For the aging metabolism, it isn't just about total protein—it's about the leucine threshold. This menu is designed to hit the ~3 g leucine "trigger" at every meal to overcome anabolic resistance and preserve lean mass.

Meal 1: The Metabolic Starter

~3 g Leucine | ~30 g Protein

• The Plate: 3 large scrambled eggs paired with 1 cup of plain Greek yogurt.

• The Sides: One slice of sprouted whole-grain toast topped with 1 tablespoon of almond or peanut butter.

• Clinical Pearl: Eggs and Greek yogurt are "fast-acting" proteins that provide a potent bolus of essential amino acids to break the overnight fast.

Meal 2: The Functional Fuel Bowl

~3 g Leucine | ~35 g Protein

• The Protein: 120 g Grilled Chicken Breast (sliced).

• The Base: 1 cup cooked quinoa and a medley of roasted Mediterranean vegetables.

• The Healthy Fats: Dressed with extra-virgin olive oil and a squeeze of lemon.

• Why Quinoa? Unlike rice, quinoa is a complete protein, contributing an extra 2–3 g of protein to help reach the leucine target.

Meal 3: The Recovery Window (Post-Exercise)

~3 g Leucine | ~25 g Protein

• The Shake: One scoop of leucine-enriched whey protein isolate mixed with water or unsweetened almond milk.

• The Carb: One medium banana.

• Mechanism: Whey protein has the highest leucine content per gram of any protein source. Pairing it with a banana provides a small insulin spike, which aids in driving those amino acids directly into the muscle tissue.

Meal 4: The Longevity Dinner

~3 g Leucine | ~30 g Protein

• The Protein: 150 g Baked Salmon Fillet.

• The Complex Carb: One medium roasted sweet potato (skin on).

• The Micros: Steamed broccoli and a large mixed green salad.

• Nutritional Synergy: Salmon provides Omega-3 fatty acids, which have been shown to sensitize the muscle cells to the anabolic effects of amino acids.

Beyond Muscle: Additional Benefits of Leucine

The clinical picture of leucine extends meaningfully beyond skeletal muscle:

Respiratory function: Martínez-Arnau et al. (2020) documented significant improvements in expiratory muscle strength—a benefit with direct implications for pneumonia prevention and breathing capacity in older adults.

Weight management: By preserving lean mass during caloric restriction, leucine helps maintain basal metabolic rate, enabling safer, more effective fat loss.

Blood glucose regulation: Emerging evidence suggests leucine may enhance insulin sensitivity and support healthier glucose metabolism.

Bone health: Leucine appears to support bone mineral density in synergy with calcium and vitamin D, though this area warrants further dedicated study.

Mitochondrial function: Leucine supports the energy-generating capacity of muscle cells, contributing to improved endurance, reduced fatigue, and better physical recovery.

Common Myths About Leucine

Myth 1: "More is always better" Truth: Beyond 3-4 grams per meal, additional leucine doesn't further stimulate MPS. Your body has a ceiling for how much it can use at once. Studies show optimal benefits at 6-9g daily.

Myth 2: "Only bodybuilders need to worry about leucine" Truth: Leucine is especially critical for older adults fighting sarcopenia—arguably more important than for young athletes. The Martínez-Arnau study proved benefits specifically in elderly populations.

Myth 3: "Plant proteins are worthless for muscle building" Truth: While plant proteins contain less leucine, strategic combining and adequate portions can meet your needs. The Ijaz et al. review acknowledges both animal and plant sources can be effective.

Myth 4: "Leucine supplementation will bulk you up" Truth: Leucine supports muscle maintenance and modest growth, especially in older adults. It won't cause unwanted "bulking" without intensive training and caloric surplus.

Myth 5: "You need to exercise for leucine to work" Truth: While combining leucine with resistance training produces the best results, the Martínez-Arnau study demonstrated that leucine alone can improve sarcopenia criteria in institutionalized adults who cannot exercise vigorously.

Frequently Asked Questions

Q1. I eat plenty of protein. Do I still need to think about leucine specifically? Possibly, yes. Total protein intake is important, but leucine distribution per meal is what actually triggers muscle protein synthesis. If your protein intake is spread unevenly—say, a small breakfast and a large dinner—you may be triggering MPS only once daily. Redistributing protein to ensure 25–30 g (with ~2.5 g leucine) at each meal is more effective for muscle preservation.

Q2. Can leucine supplementation help if I cannot exercise vigorously? Yes. The Martínez-Arnau et al. (2020) randomised controlled trial specifically demonstrated that 6 g daily of pure leucine improved walking speed and respiratory muscle strength in institutionalised older adults with limited exercise capacity. Leucine and exercise are synergistic, but leucine is not dependent on exercise to provide benefit.

Q3. Is leucine-enriched whey protein better than pure leucine powder? The Ijaz et al. (2025) systematic review suggests whey protein is advantageous because it delivers complete essential amino acids alongside the leucine stimulus. Leucine alone activates the mTOR pathway, but all nine essential amino acids need to be present for maximal muscle protein synthesis. Pure leucine powder may be preferred in those who already consume adequate total protein but need to top up their per-meal leucine dose.

Q4. Why do some people not respond to leucine supplementation? Research by Tang et al. (2026) identified elevated trimethylamine (TMA)—a gut microbiome metabolite—as a marker of impaired muscle mass response to leucine-enriched protein supplementation. This suggests that gut microbiome health may be a meaningful variable. If you are not responding as expected, consulting a clinician about gut health, vitamin D status, and overall caloric adequacy is advisable.

Q5. How long does it take to see results? Clinical trials have generally used intervention periods of 8–13 weeks before measuring outcomes. The Martínez-Arnau study ran for 13 weeks. Measurable improvements in strength, function, and lean mass typically emerge within this window when leucine intake is consistent and paired with adequate overall nutrition. Individual variation is real—factors such as baseline muscle mass, vitamin D status, activity level, and gut microbiome composition all influence outcomes.

Q6. Is leucine safe for people with kidney disease? Healthy adults tolerate leucine well at recommended doses. However, individuals with diagnosed chronic kidney disease (CKD) are often advised to moderate total protein intake to reduce renal filtration load. Any increase in protein or amino acid supplementation in the context of CKD should be discussed with a nephrologist or renal dietitian before proceeding.

Q7. Does cooking reduce the leucine content of food? No. Leucine is thermostable and survives normal cooking processes—boiling, roasting, grilling, and steaming—without meaningful degradation. You do not need to eat protein sources raw to preserve their leucine content.

Clinical pearls :

1. Leucine is the “On Switch” for Muscle Growth

Leucine doesn’t just provide raw material for muscle—it activates the machinery that builds it. By stimulating the mTOR pathway, leucine sends a powerful “grow now” signal to muscle cells, helping older adults overcome the natural slowdown in muscle-building known as anabolic resistance.

2. Older Adults Need More Leucine to Get the Same Benefit

As we age, our muscles become less responsive to protein intake. Studies show older adults need about 50% more leucine than younger individuals to trigger the same level of muscle protein synthesis. Aim for 2.5–3 grams of leucine per meal, found in roughly 25–30 grams of high-quality protein.

3. Leucine Works Best with Resistance Training—but Still Helps on Its Own

Leucine and strength training act like partners in muscle preservation. When combined, they boost muscle strength and mass far more than either alone. Yet even if exercise isn’t possible—such as in frail or institutionalized adults—6 grams of leucine daily has been shown to improve mobility and respiratory muscle strength.

4. During Weight Loss, Leucine Protects Your Muscles

When older adults reduce calories to lose fat, they often lose muscle too. Leucine helps preserve lean muscle mass while allowing fat loss to continue. This means you can slim down safely without sacrificing the strength and function you need for independence.

5. Leucine Builds Stronger, More Energetic Muscles

Leucine doesn’t just make muscles bigger—it helps them work better. By supporting mitochondrial function (the energy factories inside cells) and reducing inflammation, leucine improves endurance, energy levels, and recovery. You get stronger muscles that stay active for longer.

Your Step-by-Step Action Plan

Weeks 1–2: Audit your current intake Track protein across three representative days. Calculate approximate leucine per meal. Identify whether you are consistently hitting 2.5 g at breakfast, lunch, and dinner. Note whether you are meeting overall protein targets (1.0–1.6 g/kg body weight daily).

Weeks 3–4: Optimise your plate Restructure meals to include 25–30 g of high-quality protein at each sitting. Consider leucine-enriched whey protein as a practical supplement if food alone is insufficient. If exercise is not currently possible, begin 6 g daily leucine supplementation.

Weeks 5–8: Add resistance training if able Even two sessions weekly—focusing on legs, back, and upper body—dramatically amplifies leucine's anabolic effects. Time a leucine-rich meal or shake within an hour of each session.

Week 13 onwards: Assess and maintain Evaluate functional changes: walking speed, stair climbing ease, grip strength, energy levels. Adjust as needed. This is not a short-term fix—it is a lifestyle recalibration. The evidence base supports long-term, consistent leucine-targeted nutrition as a foundational strategy for healthy muscular aging.

Key Takeaways

✓ Leucine, a branched-chain amino acid, activates the mTOR pathway—the central driver of muscle protein synthesis—functioning as both a structural substrate and a metabolic signal

✓ Current evidence supports leucine-enriched protein, particularly whey, combined with resistance training as one of the most effective strategies for preventing and managing Sarcopenia

✓ Aging muscle exhibits anabolic resistance, requiring approximately 40–50% higher leucine intake to achieve the same muscle-building response seen in younger individuals

✓ Randomized clinical trials show that ~6 g/day leucine can improve functional outcomes (e.g., gait speed, respiratory strength) even in non-exercising or frail older adults

✓ The per-meal leucine threshold (2.5–3 g) is critical—distribution across meals is more effective than consuming protein in a single large dose

✓ Combining leucine intake with resistance exercise produces synergistic improvements in muscle strength, mass, and physical performance

✓ During caloric restriction, leucine helps preserve lean mass and metabolic rate, supporting healthier fat loss in older adults

✓ Both whey protein (complete amino acid profile) and pure leucine supplementation are evidence-based options; selection should depend on total protein intake and clinical context

✓ Emerging data suggest benefits beyond skeletal muscle, including respiratory muscle function, mitochondrial efficiency, and metabolic health

✓ Leucine is well tolerated at 6–9 g/day in healthy adults; clinical guidance is recommended in patients with renal disease or metabolic disorders

✓ Even in institutionalized or mobility-limited populations, leucine provides measurable functional benefits without the need for intensive exercise

✓ Long-term consistency (≥12 weeks) is essential—regular daily intake aligned with meals produces the most reliable improvements in muscle health and function

Author’s Note

This article was written with a dual purpose: to bridge the gap between molecular science and real-world clinical practice, and to provide both clinicians and patients with a clear, actionable framework for preserving muscle health across the lifespan. The topic of leucine and age-related muscle loss sits at the intersection of nutrition, metabolism, and functional aging—fields that are rapidly evolving with new evidence.

While the role of Sarcopenia is increasingly recognized as a major determinant of morbidity, frailty, and loss of independence, it remains underdiagnosed and often undertreated in routine clinical care. The emerging science around leucine and the mTOR pathway provides a powerful, evidence-based opportunity to intervene early and effectively.

However, it is important to emphasize that no single nutrient operates in isolation. Leucine functions within a broader physiological context that includes total protein intake, physical activity—particularly resistance training—micronutrient sufficiency (such as vitamin D), and increasingly, gut microbiome health. The goal of this article is not to present leucine as a “magic bullet,” but as a strategically important component of an integrated approach to healthy aging.

Clinical recommendations should always be individualized. Factors such as age, comorbidities, renal function, dietary patterns, and functional status must guide implementation. Readers are encouraged to interpret the information presented here in consultation with a qualified healthcare professional.

Ultimately, preserving muscle is not merely about strength or appearance—it is about maintaining autonomy, metabolic health, and quality of life. The science is clear: with the right interventions, age-related muscle loss is not inevitable, but modifiable.

Ready to start? Check out our Practical Sample Protocol for hitting your leucine threshold every day.

Leucine Threshold Explained: How Much Protein Per Meal to Build Muscle (Science-Based Guide) | DR T S DIDWAL

Disclaimer: This article is intended for general health education and does not constitute personalised medical advice. Consult a qualified healthcare professional before beginning any new supplementation regimen, particularly if you have an existing health condition or are taking prescription medications.

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Who Gets Sarcopenia? Key Risk Factors & High-Risk Groups Explained | DR T S DIDWAL

Sarcopenia: The Complete Guide to Age-Related Muscle Loss and How to Fight It | DR T S DIDWAL

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References

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Huang, C., & Hsieh, M. H. (2025). Effects of leucine supplementation in older adults with sarcopenia: A meta-analysis. Nutrients, 17(15), 2413. https://doi.org/10.3390/nu17152413

Ijaz, A., Ain, H. B. U., Tufail, T., Mariam, R., Noreen, S., Amjad, A., Ikram, A., Arshad, M. T., & Abdullahi, M. A. (2025). Enhancing muscle quality: Exploring leucine and whey protein in sarcopenic individuals. Journal of Cachexia, Sarcopenia and Muscle, 16(5), e70060. https://doi.org/10.1002/jcsm.70060

Katsanos, C. S., Kobayashi, H., Sheffield-Moore, M., Aarsland, A., & Wolfe, R. R. (2006). A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly. American Journal of Physiology: Endocrinology and Metabolism, 291(2), E381–E387. https://doi.org/10.1152/ajpendo.00488.2005

Lin, X., Zhang, Y., Pu, J., & Peng, Y. (2026). Targeting muscle–vasculature crosstalk in aging through the integrative roles of L-citrulline, leucine, and exercise: Focus on muscle metabolism, vascular function, and sarcopenia prevention. Frontiers in Nutrition, 12, 1739173. https://doi.org/10.3389/fnut.2025.1739173

Martínez-Arnau, F. M., Fonfría-Vivas, R., Buigues, C., Castillo, Y., Molina, P., Hoogland, A. J., van Doesburg, F., Pruimboom, L., Fernández-Garrido, J., & Cauli, O. (2020). Effects of leucine administration in sarcopenia: A randomized and placebo-controlled clinical trial. Nutrients, 12(4), 932. https://doi.org/10.3390/nu12040932

Tang, H. Y., Lo, C. J., Ho, H. Y., et al. (2026). Elevated trimethylamine levels characterize impaired muscle mass response to leucine-enriched protein supplementation in older adults at risk of sarcopenia. npj Aging. https://doi.org/10.1038/s41514-026-00375-9

Verreijen, A. M., Verlaan, S., Engberink, M. F., Swinkels, S., de Vogel-van den Bosch, J., & Weijs, P. J. (2015). A high whey protein-, leucine-, and vitamin D-enriched supplement preserves muscle mass during intentional weight loss in obese older adults: A double-blind randomized controlled trial. The American Journal of Clinical Nutrition, 101(2), 279–286. https://doi.org/10.3945/ajcn.114.090290

Last Updated: 30 April 2026