High-quality animal proteins are essential, and adults should derive 45 to 60% of their total protein intake from them to ensure a sufficient level of other nutrients.

noli's read

This advice highlights the high nutritional density and amino acid profile (such as leucine) of animal proteins, which are often easier to obtain than via plant-based sources. While animal proteins are indeed rich in bioavailable micronutrients (B12, iron, zinc), asserting that there is a specific required percentage (45-60%) is not supported by a universal scientific consensus. Research shows that amino acid requirements can be met through varied diets, including plant-based ones, although this requires more rigorous planning due to the digestibility and composition of plant proteins. Studies (randomized controlled trials) indicate that muscle protein synthesis can be just as effective with plant-based sources if total intake and quality are adjusted. The figure put forward seems to be more of a strategy for optimizing nutritional density than an absolute biological necessity. In summary, the importance of protein quality for maintaining muscle mass, especially as one ages, is well established, but the exclusive share of animal origin is debated and depends on the overall dietary context.

the sources

No named source held this one up — that absence is part of the verdict.