Why You Might Be Eating Less Protein Than You Think

Protein is essential for our health—it helps build and repair tissues, supports immune function, and keeps us feeling full. But not all proteins are created equal. One way nutrition science measures protein quality is through something called the Protein Digestibility-Corrected Amino Acid Score (PDCAAS).

🧬 What Is PDCAAS?

PDCAAS is a method used to evaluate the quality of a protein based on two things:

  1. Amino Acid Profile: Does the protein contain all the essential amino acids your body needs?

  2. Digestibility: How well can your body break it down and absorb it?

The score ranges from 0 to 1.0, with 1.0 being the highest possible score—meaning the protein contains all essential amino acids in ideal proportions and is highly digestible.

📊 PDCAAS Scores for Common Protein Sources

📊 PDCAAS Scores for Common Protein Sources

Protein Source PDCAAS Score (0–1.0)

Egg (whole) 1.00

Whey protein isolate 1.00

Casein (milk protein) 1.00

Soy protein isolate 1.00

Beef 0.92

Chickpeas 0.78

Oats 0.57

Peanuts 0.52

Almonds 0.40

Rice 0.50

Wheat (whole grain) 0.42

Lentils 0.52

💡 Note: Many plant proteins score lower because they lack one or more essential amino acids or are less digestible, but combining them can improve overall protein quality (e.g., rice + beans).

🧠 Why You Don’t Need to Obsess Over PDCAAS

While PDCAAS is helpful for scientific and labeling purposes, you don’t need to hit 1.0 every time you eat. Here’s why:

  • Variety matters more than perfection: Eating a mix of plant-based proteins throughout the day naturally balances out amino acid profiles.

  • Your body recycles amino acids: It doesn't need every essential amino acid at every meal.

  • Over-focusing on PDCAAS can lead to unnecessary food restriction, especially in plant-based diets.

🥦 How to Maximize Protein Digestibility

If you're concerned about getting the most from your protein, here are 4 simple strategies:

  1. Cook your legumes and grains properly – This improves digestibility and reduces anti-nutrients.

  2. Combine complementary plant proteins – Like pairing lentils with rice or hummus with whole wheat pita.

  3. Use fermented or sprouted options – These are easier to digest and often higher in available amino acids.

  4. Include some high-PDCAAS foods if possible – Eggs, dairy, or soy products can help round out your intake.

🏷️ How to Use Nutrition Labels to Understand Protein Quality

Nutrition labels in the U.S. use % Daily Value (DV) to show how much protein a serving contributes toward the average adult’s daily needs (50g/day). However, this doesn’t reflect protein quality unless the food makes a protein claim (like “high in protein”).

Here's how to decode it:

  • If a food claims to be “high in protein,” it must have a PDCAAS of 0.8 or higher and provide at least 10% of the DV.

  • Check the ingredient list for high-quality protein sources (e.g., whey, soy protein isolate).

  • Use the % DV as a rough guide, but remember: 10g of protein from lentils isn’t the same as 10g from whey.

✅ Bottom Line

PDCAAS is a valuable tool in the world of nutrition science, but you don’t need to track it unless you're managing a medical condition or working with a dietitian for a specific goal.

To support your health:

  • Eat a variety of protein-rich foods

  • Don’t fear plant-based proteins—they can be powerful with good planning

  • Focus on overall dietary balance, not just isolated numbers

Got questions about building a protein-rich, balanced plate? Let’s talk in the comments or book a session with a registered dietitian!

Lisa Moskovitz