Should I take leucine?

Our read is that leucine plays a critical role in muscle protein synthesis, especially after exhaustive exercise, and is essential for avoiding sarcopenia, according to Peter Attia and Paul Saladino.

However, experts like Peter Attia and Rhonda Patrick suggest that supplemental branched-chain amino acids (BCAAs), including leucine, may not offer additional benefits for muscle protein synthesis if total protein intake is already sufficient.

Paul Saladino also highlights potential downsides of high leucine intake, such as increased fatty acid accumulation and insulin secretion, while Peter Attia and Andrew Huberman caution against supplementing with leucine alone.

• 01Peter Attia states that muscle is in a catabolic state after exhaustive exercise until sufficient leucine is consumed to reverse it.
• 02Paul Saladino emphasizes that adequate threonine and leucine are critical for avoiding sarcopenia (2x).
• 03Rhonda Patrick notes that older adults who exercise can overcome age-related reduced sensitivity to leucine.
• 04Paul Saladino points out that red meat contains significantly more leucine (2.5g per 100g) than most plant-based foods, milk, and eggs.
• 05Rhonda Patrick mentions that BCAAs and glycine can aid recovery after training.
• 06David Sinclair suggests that mTOR activation, while building muscle, can also trigger autophagy, a longevity-promoting cellular recycling process.
• 07Rhonda Patrick indicates that leucine is readily absorbed in its free form, with taste masking being the main challenge.
• 08Peter Attia states that Sestrin is the receptor for leucine, detecting its presence and signaling to mTOR.
• 09Paul Saladino claims that insulin, not animal proteins, is the primary driver of mTOR activation, and mTOR should be cycled.

Peter Attia and Rhonda Patrick (3x) state that supplemental branched-chain amino acids do not benefit muscle protein synthesis if total protein intake is sufficient. Peter Attia and Andrew Huberman (3x) advise against supplementing with leucine alone, suggesting BCAAs should be supplemented together. Paul Saladino warns that consuming a diet higher in leucine stimulates the mTOR pathway, which can increase fatty acid accumulation in muscle and liver, chronic liver glucose production, increased insulin secretion, increased beta cell reproduction, and increased risk for beta cell suicide. Rhonda Patrick notes that depleting brain serotonin with large doses of branched-chain amino acids leads to impulsivity, reduced planning and memory, anxiety, depression, impaired facial expression interpretation, and reduced sensory gating. Peter Attia also states that adding five grams of leucine daily to protein intake does not provide a significant benefit. Paul Saladino also finds it difficult to obtain sufficient leucine from plant-based foods like navy beans, cottage cheese, sesame seeds, pumpkin seeds, and eggs.

The verdict could change if new evidence emerges demonstrating a clear, independent benefit of leucine supplementation beyond adequate total protein intake, or if further research clarifies the long-term effects of chronic mTOR activation from leucine. Additionally, more data on the optimal cycling of mTOR activation and the specific physiological contexts where leucine supplementation is most effective would be valuable.