Research
Micronutrients & recovery
Leucine supplementation can rescue muscle protein synthesis in older adults when protein doses are sub-optimal, but provides no additional benefit if the total protein dose is already sufficient (>35g).
If you can't eat a large meal (30g+ protein), adding a leucine-rich source (like whey or a leucine supplement) can help trigger muscle building. But if you are already eating a large, high-protein meal, you don't need extra leucine.
GoodQualifiesHIGH confidence
Importantly, additional leucine ingestion confers no significant benefit when the protein bolus provided is sufficient (>35 g) to maximally stimulate MPS [115]. However, supplementing a sub-optimal dose of protein with leucine can rescue the deficit in MPS, similar to ingesting a much greater dose of protein in older adults [58,112].
Why this rating
Supported by acute metabolic studies and mechanistic explanations.
Source
Nutritional Supplements to Support Resistance Exercise in Countering the Sarcopenia of Aging
James McKendry et al. · Nutrients · 2020
DOI 10.3390/nu12072057
narrative_reviewCited 118×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Older adults require a per-meal protein dose of approximately 0.4 g/kg (or ≥30g of high-quality protein) to maximally stimulate muscle protein synthesis, which is higher than the threshold for younger adults.Good
- Distributing protein intake evenly across meals (reaching the per-meal threshold) is more effective for muscle mass and function than skewing intake toward a single large meal, provided total daily protein is adequate.Good
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