Protein Quality Explained: PDCAAS & DIAAS Scores for Indian Foods
Protein quality — not just protein grams — is measured by PDCAAS and the newer, FAO-recommended DIAAS, both of which score a protein's indispensable amino acids against digestibility. Whey isolate and egg score highest (DIAAS often >1.0); pea and rice score lower alone because pea is short on methionine and rice is short on lysine. Blending the two is a genuine, published amino-acid-complementation strategy — it improves the combined profile versus either alone, though it still typically lands below isolated whey or egg on DIAAS. KABO uses this pea+brown-rice blend; its edge is convenience and 26 vitamins & minerals, not the single highest isolated score.
- Quality ≠ quantity: two foods can supply the same grams of protein yet differ hugely in how much the body can actually use, because of amino-acid balance and digestibility — that's exactly what PDCAAS and DIAAS measure.
- DIAAS is the newer standard: FAO recommended DIAAS over PDCAAS in 2013 because it measures true ileal (small-intestine) amino-acid digestibility rather than fecal digestibility, and it is not artificially capped at 1.0 the way PDCAAS is.
- Animal & dairy proteins typically top the table: whey isolate, egg and milk/casein consistently post the highest published DIAAS values (often at or above 1.0) in peer-reviewed comparisons.
- Pea + rice is a real complementation strategy, not marketing: pea protein is naturally low in methionine and rice protein is naturally low in lysine; combining them raises the blend's weakest amino acid versus either alone — this is documented in published protein-quality and postprandial-aminoacidemia research.
- Said plainly: KABO's blend is not the top isolated score. Whey isolate and egg protein typically outscore any published pea+rice blend on DIAAS in isolation. KABO's honest advantage is an all-in-one, dairy-free format with a complementary amino profile plus 26 vitamins & minerals — not a claim to the highest protein-quality number on the market.
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What PDCAAS and DIAAS actually measure
PDCAAS (Protein Digestibility-Corrected Amino Acid Score) compares a protein's indispensable (essential) amino-acid content against a reference amino-acid pattern for human needs, then corrects for how digestible the whole protein is — historically using fecal (whole-gut) digestibility. Crucially, PDCAAS is mathematically capped at 1.0 (100%), so a protein that is genuinely excellent, like egg or whey, cannot score higher than a merely very good one once both hit the ceiling.
DIAAS (Digestible Indispensable Amino Acid Score) is the method the UN Food and Agriculture Organization (FAO) recommended in its 2013 report Dietary Protein Quality Evaluation in Human Nutrition to replace PDCAAS. DIAAS uses true ileal digestibility — how much of each individual indispensable amino acid is actually absorbed by the end of the small intestine, measured directly rather than inferred from stool output — and it is not capped at 1.0. That is why some animal and dairy proteins report DIAAS values above 1.0 in the literature, while most single plant proteins fall meaningfully below it, limited by whichever amino acid is scarcest relative to the reference pattern (the "limiting amino acid").
Both scores are per-protein-source figures under standardised test conditions; they describe the quality of the protein itself, not a specific packaged product's exact clinical score, unless that product has been directly tested.
Methodology & sources
This page is an original synthesis of published nutrition science, not a new laboratory study. Figures below are drawn from the peer-reviewed and FAO literature on protein quality, specifically:
- FAO (2013), Dietary Protein Quality Evaluation in Human Nutrition, Report 92 — the report that established DIAAS methodology and reference amino-acid patterns.
- Mathai, Liu & Stein (2017), "Values for digestible indispensable amino acid scores (DIAAS) for some dairy and plant proteins may better describe protein quality than values calculated using the concept for protein digestibility-corrected amino acid scores (PDCAAS)," British Journal of Nutrition, 117:490–499 — measured DIAAS for whey isolate, whey concentrate, milk protein concentrate, skimmed milk powder, pea protein concentrate, soy protein isolate, soy flour and whole-grain wheat in a pig model.
- Herreman et al. (2020), "Comprehensive overview of the quality of plant- and animal-sourced proteins based on the digestible indispensable amino acid score," Food Science & Nutrition — a peer-reviewed review compiling DIAAS values across food categories.
- Monteyne et al. (2024), "Postprandial plasma aminoacidemia and indices of appetite regulation following pea-rice blend, pea isolate and whey protein ingestion in healthy young adults," British Journal of Nutrition — the direct human study behind the pea+rice complementation claim used below.
- Rutherfurd, Fanning, Miller & Moughan (2015), Journal of Nutrition — comparative PDCAAS/DIAAS values across common food proteins.
- Where published DIAAS or PDCAAS figures for a specific whole food (e.g. cooked dal, chickpeas) are inconsistent, incomplete, or not standardised across labs, we mark that cell "not officially scored / estimated from amino acid profile" rather than inventing a number. Where independent studies report a range (proteins vary by processing method — isolate vs. concentrate, spray-dried vs. extruded), we show that range instead of a single false-precision figure.
- Indian food-composition context (typical serving sizes and dietary role) is cross-checked against the Indian Food Composition Tables (IFCT) 2017.
This is a reference synthesis for education, not a substitute for the original papers — we encourage checking the primary sources linked above for exact experimental conditions.
The core comparison: published protein quality scores
Rows are ordered roughly highest to lowest published DIAAS. "Not officially scored" means no standardised, widely-replicated DIAAS/PDCAAS figure exists for that exact food form in the literature we reviewed — not that the food lacks protein value.
| Protein source | PDCAAS | DIAAS (if published) | Notes / limiting amino acid |
|---|---|---|---|
| Milk protein concentrate / casein | 1.00 (capped) | ~1.09–1.18 | Consistently among the highest-quality proteins in the literature; well balanced across indispensable amino acids (Mathai et al. 2017). |
| Whey protein isolate | 1.00 (capped) | ~1.00–1.09 (some isolates reported higher) | Fast-digesting, leucine-rich; a common DIAAS "gold standard" in supplement literature (Mathai et al. 2017). |
| Egg (whole egg / egg white) | 1.00 (capped) | ~1.12–1.16 | One of the highest published DIAAS values of any single food; historic reference protein for amino-acid scoring. |
| Soy protein isolate | ~0.90–0.98 | ~0.90–0.92 | The strongest single plant protein on both scores; still slightly limited in sulphur amino acids (methionine + cysteine). |
| Pea protein (isolate/concentrate) | ~0.82–0.89 | ~0.62–0.82 (varies by processing) | Limiting amino acid: methionine (sulphur amino acids). Rich in lysine, which is exactly what complements rice below. |
| Pea + brown rice protein blend (KABO's approach) | Not officially scored as a single standardised product | Not officially scored / estimated from amino acid profile | No single FAO/peer-reviewed DIAAS figure exists for a specific commercial pea+rice ratio. Published amino-acid-complementation science (Monteyne et al. 2024) shows the blend raises postprandial essential-amino-acid and lysine availability versus pea alone, because rice's methionine offsets pea's shortfall and pea's lysine offsets rice's shortfall. Said plainly: this typically still lands below isolated whey or egg on DIAAS. |
| Chickpeas (cooked/besan) | ~0.71–0.78 | Not officially scored / estimated from amino acid profile | Better balanced than most legumes; limiting amino acid still sulphur amino acids, but less severely than pea. |
| Lentils / masoor & other dals (cooked) | ~0.52–0.63 | Not officially scored / estimated from amino acid profile | Good lysine, low methionine — the classic reason Indian thalis pair dal with rice or roti. |
| Dal + rice/roti (traditional Indian combo) | Not a single standardised score (combination food) | Not officially scored / estimated from amino acid profile | The same complementation logic as pea+rice, applied at the plate level for centuries: cereal supplies methionine, pulse supplies lysine. |
| Peanuts | ~0.46–0.52 | ~0.47 | Limited by lysine and sulphur amino acids; useful protein source but not a complete one alone. |
| Brown rice protein (isolate) | ~0.42–0.53 | ~0.37–0.42 | Limiting amino acid: lysine (only around 31 mg digestible lysine/g protein vs. an FAO reference of ~48 mg/g). Rich in methionine, which is what pea protein lacks. |
| Wheat / whole-wheat atta | ~0.40–0.45 | ~0.39–0.45 (wheat gluten alone scores lower, ~0.25) | Lysine is the limiting amino acid, similar to rice; one reason Indian diets traditionally pair wheat/rice staples with dal. |
| Quinoa (cooked) | Not officially scored (limited standardised data) | Not officially scored / estimated from amino acid profile | Often described as "more complete" than most grains due to a comparatively balanced amino-acid profile, but a widely-replicated DIAAS figure is not established in the literature we reviewed. |
Interlinked reading: see our companion analyses on best plant protein in India, best protein powder in India, and the Indian protein cost index.
Why blending pea and rice protein is real amino-acid science, not just marketing
Amino-acid complementation is not a novel or KABO-specific idea — it is the same principle behind pairing dal with rice or roti on an Indian thali, and it has decades of nutrition-science backing. The logic is straightforward: pea protein's limiting (scarcest) amino acid is methionine, while rice protein's limiting amino acid is lysine. Neither is "incomplete" in the sense of missing an amino acid entirely — both contain all nine indispensable amino acids — but each is relatively low in one, which caps its DIAAS/PDCAAS score. Combine the two in the right ratio, and rice's methionine tops up pea's shortfall while pea's lysine tops up rice's shortfall, raising the blend's overall limiting-amino-acid score above either ingredient alone.
This is not a theoretical claim: a 2024 British Journal of Nutrition study (Monteyne et al.) directly measured postprandial plasma amino acids after a pea-rice protein blend versus pea isolate and whey protein in healthy adults, and found the blend improved essential-amino-acid and lysine availability compared with pea alone. Food-processing research (steam-injection studies on 2:1 pea:rice blends) has separately shown the blending process itself does not damage available lysine.
The honest limit: complementation narrows the gap versus a single plant protein, but it does not automatically surpass isolated animal proteins like whey or egg, which start from an already well-balanced amino-acid profile and score highest in nearly every published comparison above. A pea+rice blend is a genuinely good plant-based strategy for closing amino-acid gaps — it is not, and should not be marketed as, the single highest-scoring protein source available.
Where KABO fits — honestly
KABO Butter Coffee uses a pea + brown-rice protein blend, delivering 23.11g of protein per 54g serving (23–25g range), specifically because this combination is a real, published way to offset pea's lower methionine with rice's methionine, and rice's lower lysine with pea's lysine. Read plainly against the table above, this blend is not claimed to be the single highest isolated protein-quality score on the market — whey protein isolate and egg protein typically score higher on DIAAS in isolation, and we say so directly rather than obscure it.
KABO's actual case is different: it is a dairy-free, lactose-free, FSSAI-licensed all-in-one shake that pairs this complementary plant-protein blend with 60+ superfoods, 8 billion CFU probiotics, and 26 vitamins & minerals — including biotin at 40mcg (100% RDA) — with no artificial sweeteners, from Rs.2,499. If your priority is the single highest isolated protein-quality number, an isolated whey or egg-protein product is the honest recommendation. If your priority is a convenient, plant-based, complete-nutrition daily habit that also covers micronutrients most Indian diets fall short on, that is where KABO's blend is designed to help. For more on the underlying vitamin coverage, see our Indian vegetarian micronutrient gap analysis, our vegan protein sources in India guide, and the product itself at KABO Butter Coffee.
How to cite this: KABO, Protein Quality Explained: PDCAAS & DIAAS Scores for Indian Foods, kabo.co.in, July 2026.
Frequently asked questions
What is the difference between PDCAAS and DIAAS?
PDCAAS (Protein Digestibility-Corrected Amino Acid Score) scores a protein's indispensable amino acids against a reference pattern, corrected for fecal (whole-gut) digestibility, and is capped at 1.0. DIAAS (Digestible Indispensable Amino Acid Score) is the method FAO recommended in 2013 to replace it, using true ileal (small-intestine) digestibility of each individual amino acid, and it is not capped at 1.0. DIAAS is considered more precise, though PDCAAS remains widely used on labels in some markets.
Does pea + rice protein score higher than whey or egg protein?
No, and we say this plainly: published DIAAS data consistently shows whey protein isolate and egg protein scoring at or above 1.0, while even a well-blended pea+rice combination typically scores lower. Blending pea and rice is a genuine amino-acid-complementation strategy that improves on either ingredient alone, but it has not been shown to surpass isolated whey or egg in standardised comparisons.
Why do pea protein and rice protein complement each other?
Pea protein's limiting amino acid is methionine; rice protein's limiting amino acid is lysine. Combining the two means rice's methionine content offsets pea's shortfall, and pea's lysine content offsets rice's shortfall, raising the blend's overall amino-acid completeness above either source in isolation — a principle demonstrated in postprandial human studies (Monteyne et al. 2024, British Journal of Nutrition) and long practised in Indian diets through dal-with-rice or dal-with-roti combinations.
Why don't lentils, chickpeas and quinoa have a listed DIAAS score in this table?
Because a widely-replicated, standardised DIAAS figure for these specific whole foods was not found in the peer-reviewed literature we reviewed for this page. Rather than estimate a precise-looking number that isn't backed by a study, we mark those cells "not officially scored / estimated from amino acid profile," consistent with our data-integrity approach across this table.
Should I choose a protein purely by its PDCAAS/DIAAS score?
Score is one useful input, not the whole picture. Total daily protein intake, how the protein fits your diet (vegetarian, vegan, dairy-free), cost, convenience, and any accompanying nutrients (like KABO's 26 vitamins & minerals) all matter too. If maximising isolated protein-quality score is your only goal, whey isolate or egg protein are the well-documented top choices. If you want a plant-based, all-in-one daily nutrition habit, a complementary blend like pea+rice is a legitimate, honestly-positioned alternative.
Data disclaimer: PDCAAS and DIAAS values above are drawn from published FAO methodology and peer-reviewed nutrition-science literature (see Methodology & sources); values vary across studies depending on processing method, test population and reference pattern used, which is why several figures are shown as ranges. Where no standardised score was found, we say so rather than estimate a number. This article is general nutrition information, not medical advice, and does not diagnose, treat, cure or prevent any disease; consult a doctor or registered dietitian for individual guidance.