Skeletal muscle plays essential roles in movement, heat production, and glucose and lipid metabolism, but muscle mass gradually declines with age. Branched-chain amino acids (BCAAs)—leucine, isoleucine, and valine—are essential amino acids that can be directly utilized by skeletal muscle. Research suggests that BCAAs may support muscle protein synthesis, reduce muscle breakdown, alleviate exercise-related fatigue, and help relieve delayed onset muscle soreness (DOMS). With growing research interest, BCAAs are also finding broader applications in sports nutrition, functional foods, and foods for special medical purposes.
Skeletal muscle is the largest metabolic organ in the human body. It is responsible not only for movement and heat production, but also plays an important role in glucose and lipid metabolism. After adulthood, skeletal muscle mass decreases by approximately 0.5%–1% each year. This decline accelerates after the age of 40. By the age of 70, cumulative muscle loss may reach approximately 30%, while by the age of 80, it may reach as much as 50%. When muscle loss reaches 30%, normal physical function may be affected; when muscle loss reaches 40%, it may even become life-threatening.
There is a substance that can be directly taken up and utilized by skeletal muscle, promote muscle protein synthesis, and help alleviate muscle fatigue. It is BCAA—branched-chain amino acids.
What Are BCAAs?
Branched-chain amino acids (BCAAs) refer collectively to three amino acids: leucine, isoleucine, and valine. They are essential amino acids that the human body cannot synthesize on its own and must therefore obtain from external sources through food or dietary supplements. BCAAs are naturally present in protein-rich foods such as meat, poultry, fish, eggs, dairy products, and soy products.
Unlike most amino acids that require metabolism in the liver, one notable characteristic of BCAAs is that they can bypass the liver and be directly taken up and utilized by skeletal muscle, supporting protein synthesis and energy supply.
How Do BCAAs Act on Muscle?
The three amino acids in BCAAs each play different but complementary roles in muscle metabolism. Leucine is responsible for activating the mTOR signaling pathway and promoting muscle protein synthesis; isoleucine participates in the regulation of glucose metabolism and provides energy for muscle activity; while valine is more closely associated with muscle tissue repair and energy metabolism.
1) Promoting Muscle Protein Synthesis and Preventing Muscle Loss
BCAAs can promote muscle protein synthesis while inhibiting protein breakdown. During exercise, BCAAs can bypass hepatic metabolism and be rapidly taken up by skeletal muscle, providing energy for muscles and reducing muscle breakdown. In addition, leucine can activate the central mTOR signaling system and promote muscle protein synthesis.
2) Fighting Fatigue and Accelerating Exercise Recovery
BCAAs have both anti-central-fatigue and anti-muscle-fatigue effects. Tryptophan is a precursor for the synthesis of the neurotransmitter serotonin (5-HT), and elevated 5-HT levels are considered to be one of the key factors associated with the development of central fatigue. BCAAs can reduce serum tryptophan concentrations, thereby lowering 5-HT levels, effectively alleviating central fatigue, reducing the sensation of muscle fatigue, and shortening physical recovery time.
3) Reducing Muscle Damage and Soreness
BCAAs can effectively alleviate delayed onset muscle soreness (DOMS) following exercise. DOMS generally occurs within 24 hours after strenuous exercise and usually reaches its peak within 72 hours. BCAAs may reduce muscle fiber damage by promoting skeletal muscle protein synthesis and reducing muscle protein breakdown. At the same time, they can regulate the release of inflammatory factors, reduce post-exercise inflammatory responses, alleviate DOMS, and help reduce feelings of muscle soreness and discomfort.
Market and Product Applications
According to data from QY Research, the global BCAA market was valued at USD 273 million in 2025 and is expected to reach USD 346 million by 2032, with a compound annual growth rate (CAGR) of 3.5% during the forecast period from 2026 to 2032.
QY Research
1) Dietary Supplements
Sports nutrition remains the core application area for BCAAs, while product formats continue to evolve. Traditional powders still account for a major share of the market, while capsules and tablets are also growing rapidly.
2) Functional Foods
BCAAs are increasingly being incorporated into functional beverages. For example, functional foods in beverage form may combine whey protein with BCAAs, providing new options for consumers seeking nutritional support after exercise.
3) Foods for Special Medical Purposes
Foods for special medical purposes (FSMPs) represent one of the most promising emerging application areas for BCAAs. These products are positioned neither as ordinary dietary supplements nor as pharmaceutical drugs, but rather as nutritional products designed to provide BCAA supplementation for individuals with specific medical nutritional needs.
References
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Wang D.H., Cai X.Q., Luo H.R., et al. Research Progress on the Physiological Functions of Branched-Chain Amino Acids [J]. Journal of China West Normal University (Natural Sciences), 2026, 47(2): 126–135.
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Zhang X.N. A Randomized, Double-Blind, Crossover Study on the Effects of Acute Branched-Chain Amino Acid Supplementation on Explosive Performance in College 3×3 Basketball Players [D]. Chengdu Sport University, 2025.
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Choi H.B., Hyun S., Koo H.S. The role of BCAA metabolism in metabolic health and disease [J]. Experimental & Molecular Medicine, 2024, 56(7): 1552–1559.
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Sonia R., Qiaochu L., Andrea A., et al. Reprograming of proteasomal degradation by branched chain amino acid metabolism [J]. Aging Cell, 2022, 21(12): e13725–e13725.