Key facts
- Higher-quality proteins contain all essential amino acids.
- Measured by scores like DIAAS and PDCAAS.
- Animal proteins generally rank higher than most plant proteins.
- Variety and total intake can offset lower-quality sources.
Not all protein is equal. A source's quality depends on two things: whether it contains all nine essential amino acids in good amounts (especially leucine), and how well your body digests and absorbs it. Scoring systems like DIAAS and PDCAAS rank sources on these measures.
Animal proteins — whey, eggs, meat, dairy — tend to score highest because they're complete and highly digestible. Many plant proteins are lower in one or two amino acids, but this matters less when total protein is high and sources are varied. For most people, hitting a solid daily protein target from mixed sources covers quality concerns.
Frequently asked questions
Is animal protein better than plant protein?
Per gram, animal proteins are usually higher quality and more complete. But plant-based eaters can match the benefit by eating more total protein and combining varied sources.
Does protein quality matter if I eat enough total protein?
Less so. At high total protein intakes from varied sources, any gaps in individual sources are easily filled, so quality becomes a smaller concern.
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