Digestible Indispensable Amino Acid Score (DIAAS) is a protein quality method proposed in March 2013 by the Food and Agriculture Organization to replace the current protein ranking standard, the Protein Digestibility Corrected Amino Acid Score (PDCAAS).
The DIAAS accounts for amino acid digestibility at the end of the small intestine, providing a more accurate measure of the amounts of amino acids absorbed by the body and the protein's contribution to human amino acid and nitrogen requirements. This is in contrast to the PDCAAS, which is based on an estimate of digestibility over the total digestive tract. Values stated using this method generally overestimate the amount of amino acids absorbed. [1]
Amino acid requirements were determined in two parts. The amino acid distribution of breast milk was used for the 0 to 6 month age range, and existing amino acid data was used for older ages after adjustment for digestibility. The reference amino acid requirements are presented below. [2] : 29
Requirements by age (mg/g protein) | |||
---|---|---|---|
Amino acid | 0 to 6 months | 6 months to 3 years | Over 3 years |
Histidine | 21 | 20 | 16 |
Isoleucine | 55 | 32 | 30 |
Leucine | 96 | 66 | 61 |
Lysine | 69 | 57 | 48 |
Methionine + Cysteine (SAA) | 33 | 27 | 23 |
Phenylalanine + Tyrosine (AAA) | 94 | 52 | 41 |
Threonine | 44 | 31 | 25 |
Tryptophan | 17 | 8.5 | 6.6 |
Valine | 55 | 43 | 40 |
The table shows the ratings of selected foods comparing PDCAAS to DIAAS. [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] The quality of various sources of protein depends on how it is processed, refined, stored, or cooked. [12] [15] [16] (preparation is unspecified for some values in the table, but does not necessarily differ in preparation from the foods where preparation is specified). A major difference between DIAAS and PDCAAS, is that PDCAAS is truncated at 100%, while DIAAS is not. Multiple protein sources can also be combined to increase DIAAS, which can be effective at raising the max DIAAS of plant-based diets. [13]
Food | PDCAAS | DIAAS for 0.5-3 yo [13] | Limiting AA |
---|---|---|---|
Milk Protein Concentrate [3] [4] | 1.00 | 1.18 | Met + Cys |
Whey Protein Isolate [3] [4] | 1.00 | 1.09 | Val |
Soy Protein Isolate [3] [4] | 0.98 | 0.898 | Met + Cys |
Pea Protein Concentrate [3] [4] | 0.893 | 0.822 | Met + Cys |
Rice Protein Concentrate [3] [4] | 0.419 | 0.371 | Lys |
Whole milk powder [5] | 1.000 | 1.159 | |
Tilapia [17] | 1.00 | ||
Tuna (canned in oil) [16] | 1.00 | ||
Chicken breast [3] | 1.00 | 1.08 | Trp |
Pork [13] | 1.17 | ||
Beef [5] | 1.000 | 1.116 | |
Whole milk [3] | 1.00 | 1.14 | Met + Cys |
Egg (hard boiled) [3] | 1.00 | 1.13 | His |
Egg [13] | 1.01 | ||
Chickpeas [3] | 0.74 | 0.83 | Met + Cys |
Tofu [3] | 0.70 | 0.97 | Met + Cys |
Peas [5] | 0.782 | 0.647 | |
Cooked peas [3] [4] | 0.597 | 0.579 | Met + Cys |
Soybean [5] | 1.000 | 0.996 | |
Soy [13] | 0.91 | Met + Cys | |
Soya Flour [14] | 1.00 | 1.05 | |
Fava Bean [13] | 0.55 | Met + Cys | |
Cooked kidney beans [4] | 0.648 | 0.588 | |
Roasted peanuts [4] | 0.509 | 0.434 | |
Almonds [3] | 0.39 | 0.40 | Lys |
Wheat [5] [13] | 0.463 | 0.40-0.48 | |
Wheat flour [16] | 0.40 | ||
Wheat bran [5] [4] | 0.53-0.60 | 0.41-0.49 | |
Barley [5] | 0.591 | 0.472 | |
Rye [5] | 0.553 | 0.476 | |
Triticale [5] | 0.553 | 0.498 | |
Corn [13] [16] | 0.37 | 0.36 | Met + Cys |
Corn Grain [5] | 0.473 | 0.424 | |
Corn-based cereal [3] [4] | 0.078 | 0.012 | Lys |
Rice [13] | 0.47 | Lys | |
Cooked rice [3] [4] | 0.616 | 0.595 | Lys |
Oats [13] | 0.57 | Lys | |
Cooked rolled oats [4] | 0.670 | 0.542 | |
Potato [13] | 0.99 | 1.00 | |
Quinoa [11] | 0.677 | ||
Quinoa flour [16] | 0.79 | ||
Gelatin [13] | 0.02 | Trp | |
Wheat/potato (30/70) [13] | 1.00 | ||
Vegetables [18] | 0.73-0.89 | ||
Tubercles [18] | 0.74-0.89 | ||
Fresh Fruits [18] | 0.64-0.76 | ||
Dried Fruits [18] | 0.48-0.66 | ||
Legumes [18] | 0.70-0.89 |
A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excreted by cells to create non-cellular structures such as hair, scales, feathers, or exoskeletons. Some nutrients can be metabolically converted into smaller molecules in the process of releasing energy such as for carbohydrates, lipids, proteins and fermentation products leading to end-products of water and carbon dioxide. All organisms require water. Essential nutrients for animals are the energy sources, some of the amino acids that are combined to create proteins, a subset of fatty acids, vitamins and certain minerals. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves. Fungi live on dead or living organic matter and meet nutrient needs from their host.
An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life forms, the nine amino acids humans cannot synthesize are valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, threonine, histidine, and lysine.
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