Evidence supporting the use of: L-leucine
For the health condition: Muscle Tone (lack of)

Links: Go back one page, Tool main page, Ingredients list, Health conditions list, Body systems list

Synopsis

Source of validity: Scientific
Rating (out of 5): 4

L-leucine is an essential branched-chain amino acid (BCAA) that plays a critical role in muscle protein synthesis. Scientific research has consistently demonstrated that leucine acts as a key regulator in the initiation of muscle protein synthesis via the mTOR signaling pathway. Supplementation with leucine, either alone or as part of BCAA mixtures, has been shown to enhance muscle protein synthesis rates, particularly in situations where muscle tone or mass is compromised, such as aging (sarcopenia), immobilization, or certain chronic illnesses.

Clinical studies in both young and elderly populations indicate that leucine supplementation can help maintain or improve muscle mass and function, especially when combined with resistance exercise or adequate protein intake. For example, a 2017 review in Frontiers in Nutrition highlighted that leucine-enriched diets improve muscle protein synthesis and muscle mass in older adults. Furthermore, meta-analyses have reported modest but significant improvements in muscle strength and function with leucine or BCAA supplementation in individuals experiencing muscle wasting or weakness.

However, while leucine is effective in stimulating muscle protein synthesis, its benefits may be maximized when used in conjunction with other essential amino acids and physical activity. Overall, the scientific evidence supporting the use of leucine for improving or maintaining muscle tone is robust, though not absolute, earning it a high evidence rating of 4 out of 5.

More about L-leucine
More about Muscle Tone (lack of)