Understanding Protein: Quality vs. Quantity
Protein is a macronutrient vital for countless bodily functions, from building and repairing tissues to producing enzymes and hormones. It is composed of building blocks called amino acids. There are 20 amino acids, nine of which are considered 'essential' (EAAs) because the body cannot produce them and must obtain them from food.
Proteins are broadly classified into two categories based on their EAA profile:
- Complete proteins: Contain all nine essential amino acids in sufficient quantities. Animal products like meat, fish, poultry, and eggs are classic examples. Some plant-based sources like soy, quinoa, and buckwheat are also complete.
- Incomplete proteins: Lack or are very low in one or more essential amino acids. Most plant proteins from grains, legumes, nuts, and vegetables fall into this category.
Beyond the EAA profile, protein quality is also measured by its digestibility and bioavailability—how well the body can actually absorb and use the amino acids. The Digestible Indispensable Amino Acid Score (DIAAS) is a modern, superior metric that assesses protein quality based on the absorption of each individual amino acid at the end of the small intestine. DIAAS often reveals higher scores for animal proteins and some high-quality plant proteins compared to many common plant sources.
The Case for Counting All Protein
The simple answer is yes, you should count all dietary protein. While some protein sources are more efficient than others, every gram contributes to your total daily intake. The body maintains a pool of amino acids from the various proteins consumed throughout the day.
An older, now largely outdated, idea was the need to meticulously combine complementary plant proteins in the same meal to form a 'complete' protein. Modern nutritional science has debunked this, emphasizing that consuming a varied and balanced diet over the course of a day is sufficient to provide all the necessary essential amino acids, even on a fully plant-based diet. For those with high protein demands, like athletes or older adults, focusing on a variety of high-quality sources is especially important to ensure optimal muscle protein synthesis, but the total cumulative intake still matters.
The Impact of Protein Digestibility and Fiber
When considering protein from non-traditional sources, especially plants, the role of fiber and digestibility becomes relevant. Plant-based proteins are often packaged with dietary fiber and other compounds that can slightly reduce their overall digestibility. This can lead to a slightly lower bioavailability of the amino acids compared to animal proteins.
However, for most healthy individuals, this difference is minor and is generally not a cause for concern as long as overall protein intake is adequate. Studies on fiber's effect on protein absorption show that while increased fiber can slightly increase fecal nitrogen excretion, the net effect is usually small and manageable. For those with very high protein requirements, prioritizing more digestible sources is a good strategy, but the incidental protein from fibrous foods should still be included in macro calculations.
Comparison of Common Protein Sources
| Source Category | Example Foods | Protein Quality (DIAAS/EAA Profile) | Typical Digestibility | Counting Method | Example (per 100g) | Incidental Protein? |
|---|---|---|---|---|---|---|
| Animal Protein | Chicken, beef, milk, eggs | Complete (high quality) | Very high | Count fully towards macro goals. | 25-30g+ | No, primary source. |
| Plant Protein (Complete) | Soy, Quinoa, Buckwheat | Complete | High (Soy) to moderate | Count fully towards macro goals. | 10-20g | No, primary source. |
| Grains | Rice, Oats, Bread | Incomplete (often low in lysine) | Can be slightly reduced by fiber | Count for cumulative effect, contribute to total intake. | 3-10g | Yes, incidental. |
| Legumes | Lentils, Beans, Peas | Incomplete (often low in methionine) | High to moderate | Count, essential for balancing plant-based diets. | 7-10g | Yes, both primary and incidental. |
| Vegetables | Broccoli, Spinach, Corn | Incomplete, low protein density | Variable, often high | Count for cumulative effect, minimal contribution. | 2-5g | Yes, incidental. |
| Nuts & Seeds | Peanuts, Almonds | Incomplete | Moderate | Count, valuable for complementing other sources. | 15-25g | Yes, both primary and incidental. |
Practical Guide to Counting Protein from Non-Protein Sources
For accurate macro tracking, especially if you have specific fitness or health goals, accounting for all protein is the best practice. Here is a step-by-step approach:
- Use a reliable tracking app: Utilize nutrition apps like MyFitnessPal or Cronometer to log your food intake. These databases typically include the protein content of all ingredients, including those from grains and vegetables.
- Use a food scale for accuracy: While volume measurements are fine for general health, a digital food scale provides the most accurate data for macro tracking, especially for ingredients like grains.
- Prioritize high-quality protein: For those with higher protein needs (e.g., athletes, bodybuilders, older adults), prioritize protein from high-quality, complete sources at each meal to maximize muscle protein synthesis.
- Balance your plate: For non-plant-based eaters, this means pairing animal protein with sides that also offer some protein. For vegans and vegetarians, this means combining different plant-based foods throughout the day to ensure a complete amino acid profile. An easy example is pairing rice with beans, which complement each other's limiting amino acids.
How to optimize your intake
Optimizing your protein intake depends on your specific goals and dietary preferences. A variety of sources is key to a healthy diet regardless of whether you're an omnivore or following a plant-based pattern.
- For muscle building: Evenly distributing protein intake throughout the day is often recommended, with 30-40g per meal being an effective dose for maximizing muscle protein synthesis. Relying solely on large, infrequent protein meals may be less effective for this goal.
- For weight management: Higher protein intake can increase satiety and support lean body mass retention during caloric deficits. Counting all protein sources is beneficial for staying within overall calorie targets while meeting this increased protein requirement.
- For vegans and vegetarians: Focus on incorporating a wide variety of plant foods. Combining sources like whole grains (e.g., brown rice, oats) with legumes (e.g., beans, lentils) or nuts and seeds ensures all essential amino acids are consumed over the day. Include complete plant proteins like soy, quinoa, or buckwheat when possible.
Conclusion
Ultimately, the question of whether you should I count protein from non-protein sources has a clear answer: yes. While not all protein sources are created equal in terms of quality and digestibility, every gram contributes to your daily total and the body's overall amino acid pool. For general health, counting all protein provides the most accurate picture of your nutritional intake. For specific goals like muscle gain or for those following a plant-based diet, prioritizing a variety of high-quality protein sources throughout the day is a sound strategy. Focus on the big picture of your entire diet, ensuring it is varied enough to provide all the essential nutrients your body needs to thrive.
Harvard Health Publishing provides further information on a variety of healthy protein sources.
