Complete Protein Sources Ranked: Bioavailability, Cost, and Macro Density Compared

Protein quality is not determined by a single number. Two foods can each contain 25 grams of protein per serving, yet deliver wildly different results for muscle protein synthesis, satiety, and overall nutrition. The difference comes down to bioavailability — how much of the protein your body can actually absorb and use — along with amino acid completeness, caloric efficiency, and practical cost.

This guide ranks over 30 protein sources using four measurable criteria: protein content per 100 grams, bioavailability score (PDCAAS and DIAAS), calories per gram of protein, and approximate cost per gram of protein. Whether you are optimizing for muscle gain, fat loss, or budget, these tables give you the data to make informed choices instead of relying on marketing claims.

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Understanding Protein Quality Metrics

Before diving into the rankings, here is what each metric means and why it matters:

Metric	What It Measures	Scale	Why It Matters
Protein per 100g	Raw protein density by weight	Grams	Higher density means less food volume needed to hit targets
PDCAAS	Protein Digestibility Corrected Amino Acid Score	0.00–1.00	WHO standard for protein quality; 1.00 is the maximum
DIAAS	Digestible Indispensable Amino Acid Score	0–150+	Newer, more accurate than PDCAAS; scores above 100 indicate excellent quality
Cal/g protein	Calories consumed per gram of protein obtained	Ratio	Lower is better for fat loss; shows caloric "cost" of protein
Cost/g protein	Approximate USD cost per gram of usable protein	USD	Based on average US grocery prices, March 2026

PDCAAS vs. DIAAS

PDCAAS has been the global standard since 1989, but it caps scores at 1.00, which means it cannot differentiate between good and excellent protein sources. DIAAS, adopted by the FAO in 2013, evaluates individual amino acids at the ileal level and allows scores above 100, providing a more granular picture. Where DIAAS data is available, we include both scores.

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Animal Protein Sources Ranked

Animal proteins generally score highest for bioavailability and amino acid completeness. The table below ranks 18 common animal protein sources.

Rank	Protein Source	Protein/100g	PDCAAS	DIAAS	Cal/g Protein	Cost/g Protein (USD)	Complete AA Profile
1	Whey protein isolate	90g	1.00	125	1.1	$0.03	Yes
2	Egg whites (cooked)	11g	1.00	113	1.5	$0.05	Yes
3	Chicken breast (skinless, cooked)	31g	1.00	108	1.6	$0.04	Yes
4	Turkey breast (skinless, cooked)	30g	1.00	108	1.6	$0.05	Yes
5	Cod (cooked)	23g	1.00	107	1.6	$0.06	Yes
6	Tilapia (cooked)	26g	1.00	107	1.6	$0.05	Yes
7	Shrimp (cooked)	24g	1.00	106	1.4	$0.07	Yes
8	Tuna (canned in water)	26g	1.00	106	1.5	$0.04	Yes
9	Whole eggs (cooked)	13g	1.00	113	2.3	$0.03	Yes
10	Salmon (cooked)	25g	1.00	106	2.1	$0.07	Yes
11	Greek yogurt (nonfat)	10g	1.00	105	1.7	$0.04	Yes
12	Cottage cheese (low-fat)	12g	1.00	105	1.8	$0.03	Yes
13	Casein protein powder	80g	1.00	118	1.2	$0.04	Yes
14	Lean beef (sirloin, cooked)	29g	1.00	111	2.0	$0.06	Yes
15	Pork tenderloin (cooked)	26g	1.00	105	2.1	$0.05	Yes
16	Lamb (leg, lean, cooked)	26g	1.00	105	2.5	$0.08	Yes
17	Bison (cooked)	28g	1.00	107	1.8	$0.09	Yes
18	Whole milk	3.3g	1.00	114	5.5	$0.02	Yes

Top animal protein takeaways

• Best bioavailability: Whey protein isolate, whole eggs, and casein lead in DIAAS scores. These are the most efficiently absorbed protein sources available.
• Best caloric efficiency: Whey isolate (1.1 cal/g protein), shrimp (1.4), and egg whites (1.5) deliver the most protein per calorie, making them ideal for fat loss phases.
• Best budget option: Whole eggs, cottage cheese, and whey isolate all come in at $0.03 per gram of protein or less, making them the most cost-effective animal proteins.
• Highest caloric cost: Whole milk requires 5.5 calories per gram of protein due to its fat and lactose content, making it a poor choice for protein-focused goals but useful for bulking.

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Plant Protein Sources Ranked

Plant proteins vary significantly in bioavailability and amino acid completeness. Some are complete proteins; most require combining with complementary sources.

Rank	Protein Source	Protein/100g	PDCAAS	DIAAS	Cal/g Protein	Cost/g Protein (USD)	Complete AA Profile	Limiting Amino Acid
1	Soy protein isolate	81g	1.00	98	1.2	$0.03	Yes	Methionine (marginal)
2	Tofu (firm)	17g	0.93	92	2.0	$0.03	Yes	Methionine (marginal)
3	Edamame	11g	0.92	90	2.2	$0.04	Yes	Methionine (marginal)
4	Tempeh	19g	0.91	86	2.6	$0.04	Yes	Methionine (marginal)
5	Pea protein isolate	80g	0.89	82	1.3	$0.03	Nearly	Methionine
6	Mycoprotein (Quorn)	11g	0.87	80	2.5	$0.06	Nearly	Methionine
7	Quinoa (cooked)	4.4g	0.81	74	5.5	$0.06	Yes	Leucine (low)
8	Buckwheat (cooked)	3.4g	0.78	71	6.2	$0.04	Yes	Lysine (marginal)
9	Chickpeas (cooked)	8.9g	0.78	68	3.7	$0.02	No	Methionine
10	Black beans (cooked)	8.9g	0.75	65	3.6	$0.01	No	Methionine
11	Lentils (cooked)	9.0g	0.72	63	2.9	$0.01	No	Methionine
12	Hemp seeds	31g	0.66	60	3.6	$0.06	Nearly	Lysine
13	Seitan (wheat gluten)	25g	0.42	40	1.5	$0.04	No	Lysine
14	Peanut butter	25g	0.52	46	4.7	$0.02	No	Methionine, Lysine
15	Almonds	21g	0.52	44	5.5	$0.04	No	Lysine
16	Oats (dry)	13g	0.57	54	5.6	$0.01	No	Lysine
17	Brown rice (cooked)	2.6g	0.56	53	7.7	$0.01	No	Lysine
18	Spirulina (dried)	57g	0.67	62	1.4	$0.10	Nearly	Methionine

Top plant protein takeaways

• Best bioavailability: Soy protein isolate is the only plant protein that matches animal sources with a PDCAAS of 1.00. Tofu, edamame, and tempeh follow closely.
• Best caloric efficiency: Soy protein isolate (1.2 cal/g protein) and pea protein isolate (1.3) rival whey in caloric efficiency.
• Best budget option: Black beans and lentils at $0.01 per gram of protein are the cheapest protein sources on this entire list, though their lower bioavailability means you need more total protein to achieve the same muscle protein synthesis.
• Complementary pairing: Legumes (low in methionine) combined with grains (low in lysine) create a complete amino acid profile. Classic examples: rice and beans, lentil soup with bread, hummus with pita.

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Combined Rankings: Top 15 Overall

When all factors are weighted equally, these protein sources deliver the best overall package:

Rank	Protein Source	Type	Protein/100g	DIAAS	Cal/g Protein	Cost/g Protein	Overall Score
1	Whey protein isolate	Animal	90g	125	1.1	$0.03	97
2	Chicken breast	Animal	31g	108	1.6	$0.04	94
3	Whole eggs	Animal	13g	113	2.3	$0.03	92
4	Soy protein isolate	Plant	81g	98	1.2	$0.03	91
5	Cottage cheese	Animal	12g	105	1.8	$0.03	90
6	Tuna (canned)	Animal	26g	106	1.5	$0.04	90
7	Turkey breast	Animal	30g	108	1.6	$0.05	89
8	Greek yogurt (nonfat)	Animal	10g	105	1.7	$0.04	88
9	Pea protein isolate	Plant	80g	82	1.3	$0.03	85
10	Tofu (firm)	Plant	17g	92	2.0	$0.03	85
11	Egg whites	Animal	11g	113	1.5	$0.05	85
12	Cod	Animal	23g	107	1.6	$0.06	84
13	Lentils	Plant	9.0g	63	2.9	$0.01	82
14	Shrimp	Animal	24g	106	1.4	$0.07	82
15	Lean beef (sirloin)	Animal	29g	111	2.0	$0.06	81

The overall score weighs DIAAS (30%), caloric efficiency (25%), cost efficiency (25%), and protein density (20%). This weighting reflects the priorities of someone training for body composition while managing a realistic grocery budget.

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Protein Pairing Guide for Plant-Based Eaters

Since most plant proteins lack one or more essential amino acids, strategic pairing is essential. The table below shows effective combinations:

Combination	Foods	Missing AA Covered	Effective DIAAS (estimated)	Practical Example
Legume + Grain	Lentils + Rice	Lysine + Methionine	~85	Dal with basmati rice
Legume + Seed	Chickpeas + Tahini	Lysine + Methionine	~80	Hummus
Soy + Grain	Tofu + Quinoa	Methionine (boosted)	~92	Tofu stir-fry with quinoa
Legume + Nut	Black beans + Pumpkin seeds	Methionine	~78	Bean salad with seed topping
Pea protein + Rice protein	Powder blend	Lysine + Methionine	~95	Blended protein shake

Important note: Complementary proteins do not need to be consumed in the same meal. Research shows that eating complementary sources within the same day is sufficient for complete amino acid availability.

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How to Use This Data for Your Goals

Fat loss

Prioritize sources with the lowest calories per gram of protein. Whey isolate, egg whites, shrimp, chicken breast, and soy isolate let you hit protein targets without exceeding your calorie budget. Tracking these numbers is straightforward with an app like Nutrola, where verified database entries ensure the protein and calorie values you log match what you actually consume.

Muscle building

Focus on high-DIAAS sources, particularly those rich in leucine (whey, eggs, chicken, beef). Aim for 1.6–2.2g of protein per kilogram of body weight from a mix of high-bioavailability sources. Spreading intake across 4–5 meals optimizes muscle protein synthesis.

Budget optimization

Eggs, cottage cheese, lentils, black beans, and whey protein are all under $0.03 per gram of protein. A weekly meal plan built around these foods can deliver 150g of daily protein for under $5 per day.

Goal	Priority Metric	Top 3 Sources
Fat loss	Cal/g protein	Whey isolate, egg whites, shrimp
Muscle gain	DIAAS score	Whey isolate, whole eggs, chicken breast
Budget	Cost/g protein	Lentils, black beans, whole eggs
Plant-based muscle gain	DIAAS + completeness	Soy isolate, tofu, pea + rice blend
Convenience	Protein/100g	Whey isolate, soy isolate, pea isolate

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Tracking Protein Quality in Practice

Raw protein numbers on a nutrition label do not tell the full story. A food labeled "25g protein" may deliver anywhere from 10g to 25g of usable protein depending on its DIAAS score. This is why tracking with a verified database matters.

Nutrola's food database includes professionally reviewed protein values that account for standard cooking methods and serving sizes. When you log chicken breast in Nutrola, the entry reflects cooked weight with accurate macros rather than a user-submitted estimate that could be raw weight, skin-on, or a different cut entirely. This precision compounds over weeks and months into meaningfully different outcomes.

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FAQ

What is the single best protein source for muscle building?

Whey protein isolate ranks highest when combining bioavailability (DIAAS 125), caloric efficiency (1.1 cal/g protein), cost ($0.03/g), and convenience. For whole foods, chicken breast and whole eggs offer the best balance of quality, cost, and versatility.

Is plant protein as effective as animal protein for building muscle?

Gram for gram, most plant proteins are 15–30% less bioavailable than animal proteins. However, soy protein isolate approaches animal protein quality with a DIAAS of 98. Plant-based athletes can match animal protein outcomes by consuming 10–20% more total protein and combining complementary sources.

How much protein do I actually absorb from beans and lentils?

With DIAAS scores of 63–68, legumes deliver roughly 60–70% of their listed protein as usable amino acids. A serving listing 18g protein from lentils provides roughly 11–13g of effectively usable protein. Pairing with grains raises this significantly.

Do I need to eat complementary proteins in the same meal?

No. Research published in the Journal of Nutrition confirms that amino acid pools remain available for complementary use across a full day of eating. As long as you consume a variety of protein sources throughout the day, complete amino acid coverage is achieved.

What is the cheapest way to get 150g of protein per day?

A combination of whole eggs (6 eggs = 36g, ~$1.20), whey protein (2 scoops = 50g, ~$1.50), chicken thighs (200g = 40g, ~$1.60), and lentils (200g cooked = 18g, ~$0.20) totals 144g of protein for approximately $4.50. Adding a cup of Greek yogurt reaches 154g for around $5.30 total.

How does cooking method affect protein bioavailability?

Cooking generally improves protein digestibility by denaturing proteins and making them more accessible to digestive enzymes. Boiling, baking, and grilling all improve bioavailability compared to raw consumption. However, excessive charring or prolonged high-heat cooking can reduce lysine availability by 5–10%.

Why do PDCAAS and DIAAS scores sometimes disagree?

PDCAAS truncates scores at 1.00, so whey protein (DIAAS 125) and cod (DIAAS 107) both receive a PDCAAS of 1.00 despite meaningful quality differences. DIAAS also measures digestibility at the ileal level rather than fecal level, providing a more accurate picture of actual absorption. DIAAS is considered the superior metric by the FAO but older studies and food labels often still reference PDCAAS.