Leucine is revered for its powerful ability to boost muscle mass and enhance athletic performance. Additionally, it helps slow down muscle deterioration in older individuals and helps keep blood sugar under control.
Leucine is essential for protein synthesis, muscle growth, and repair. It particularly benefits athletes and individuals looking to enhance muscle growth and recovery.
Keep reading and find out why you should consider taking leucine supplements!
Leucine - Foods
Amino acids are the building blocks of proteins. There are 20 amino acids in total, 9 of which are essential because our bodies cannot produce them. As a result, these amino acids must be obtained through food and supplements, with leucine being one of the key amino acids.
Leucine is an essential amino acid your body cannot produce on its own, so you need to consume it through food or supplements. Fortunately, many healthy and delicious foods are rich in leucine, including:
- meat and poultry,
- fish,
- dairy products,
- soy products,
- eggs,
- legumes,
- nuts and seeds,
- whole grains,
- spirulina.
Leucine - Health benefits
Leucine provides several health benefits, particularly by enhancing muscle protein synthesis and regulating glucose homeostasis. It is especially important for individuals at risk of muscle loss, such as older adults, and has been studied for its effects on body composition, strength, and metabolic health.
Prevents and improves sarcopenia
Sarcopenia, the age-related progressive loss of muscle mass, strength, and function, is a major concern for older adults.
Research suggests that leucine improves sarcopenia in elderly individuals by improving lean muscle mass content which helps maintain muscle function and overall mobility (1). Furthermore, leucine-rich protein supplementation, when combined with resistance training, is more effective at preventing sarcopenia than resistance training alone (3).
Supports Healthy Body Composition
Leucine has positive effects on body weight and body mass index (BMI), particularly in older individuals already prone to sarcopenia (2). It also contributes to an increase in lean body mass (LBM) (3) — the total weight of the body excluding fat. Since LBM plays a crucial role in metabolic rate, individuals with more LBM burn a greater number of calories at rest, making leucine beneficial for weight management and overall energy balance.
Enhances Muscle Strength and Growth
Leucine contributes significantly to muscle strength and volume (4), making it a key nutrient for athletes and individuals looking to maintain muscle function. It also plays a role in preventing muscle loss, mainly for late middle-aged adults (5).
Manages Blood Sugar Levels
One study shows that leucine alone has little effect on blood sugar, but when taken together with glucose, it boosts insulin release, helping to stabilize blood sugar levels (6).
Reduces inflammation
One study suggests that leucine significantly decreases levels of C-reactive protein (CRP), a biomarker of inflammation (4).
Additional Benefits of Leucine Supplementation
Research suggests that leucine or leucine-enriched protein supplementation may improve cognitive function, reduce depression symptoms, and enhance quality of life. These benefits make leucine a valuable intervention, particularly for older adults (1).
Leucine – Side Effects
Consuming the leucine found in foods is safe with minimal risk of side effects. However, consuming a leucine supplement may have potential side effects.
Fortunately, no severe side effects have been reported with leucine supplements when taken at recommended doses. However, taking leucine in very high doses (more than 500 mg per kg of body weight per day) may lead to some side effects, including:
- gastrointestinal (GI) distress (1),
- imbalance of other amino acids (1),
- elevated ammonia levels in the blood (hyperammonemia) (1),
- contribution to pellagra development and symptom worsening (7).
You can read more about the proper dosage of leucine in one of our previous articles:
Conclusion
Leucine is an essential amino acid that is crucial for protein synthesis, muscle building and repair, and blood sugar regulation. Its numerous health benefits make it particularly important for athletes, older adults, and anyone looking to increase muscle mass.
Literature sources:
- Martínez-Arnau FM, Fonfría-Vivas R, Cauli O. Beneficial effects of leucine supplementation on criteria for sarcopenia: a systematic review. Nutrients. 2019;11(10):2504. doi: 10.3390/nu11102504.
- Komar B, Schwingshackl L, Hoffmann G. Effects of leucine-rich protein supplements on anthropometric parameters and muscle strength in the elderly: a systematic review and meta-analysis. J Nutr Health Aging. 2015;19(4):437-46. doi: 10.1007/s12603-014-0559-4.
- Oh GS, Lee JH, Byun K, Kim DI, Park KD. Effect of intake of leucine-rich protein supplement in parallel with resistance exercise on the body composition and function of healthy adults. Nutrients. 2022 Oct 26;14(21):4501. doi: 10.3390/nu14214501. PMID: 36364764; PMCID: PMC9655197.
- Theis N, Brown MA, Wood P, Waldron M. Leucine supplementation increases muscle strength and volume, reduces inflammation, and affects wellbeing in adults and adolescents with cerebral palsy. J Nutr. 2021 Jan 4;151(1):59-64. doi: 10.1093/jn/nxaa006.
- Kang Y, Kim N, Choi YJ, Lee Y, Yun J, Park SJ, Park HS, Chung YS, Park YK. Leucine-enriched protein supplementation increases lean body mass in healthy Korean adults aged 50 years and older: a randomized, double-blind, placebo-controlled trial. Nutrients. 2020 Jun 18;12(6):1816. doi: 10.3390/nu12061816. PMID: 32570811; PMCID: PMC7353448.
- Kalogeropoulou D, Lafave L, Schweim K, Gannon MC, Nuttall FQ. Leucine, when ingested with glucose, synergistically stimulates insulin secretion and lowers blood glucose. Metabolism. 2008 Dec;57(12):1747-52. doi: 10.1016/j.metabol.2008.09.001. PMID: 19013300.
- Badawy AA, Lake SL, Dougherty DM. Mechanisms of the pellagragenic effect of leucine: stimulation of hepatic tryptophan oxidation by administration of branched-chain amino acids to healthy human volunteers and the role of plasma free tryptophan and total kynurenines. Int J Tryptophan Res. 2014 Dec 4;7:23-32. doi: 10.4137/IJTR.S18231. PMID: 25520560; PMCID: PMC4259507.
