{{Short description|Percentage of ingested nitrogen that is retained in the body}} The '''net protein utilization''' ('''NPU''') is the percentage of ingested nitrogen that is retained in the body.
==Rating== It is used to determine the nutritional efficiency of protein in the diet,<ref name=EFSA2012>{{cite journal |title=Scientific Opinion on Dietary Reference Values for protein: Dietary Reference Values for protein |journal=EFSA Journal |date=February 2012 |volume=10 |issue=2 |pages=2557 |doi=10.2903/j.efsa.2012.2557|s2cid=139100064 |hdl=2434/257730 |hdl-access=free }}</ref>{{rp|p=11}} that is, it is used as a measure of "protein quality" for human nutritional purposes.<ref>[https://labdoor.com/article/protein-quality-the-4-most-important-metrics Protein Quality–The 4 Most Important Metrics]</ref>
As a value, NPU can range from 0 to 1 (or 100), with a value of 1 (or 100) indicating 100% utilization of dietary nitrogen as protein and a value of 0 an indication that none of the nitrogen supplied was converted to protein.
Certain foodstuffs, such as eggs or milk, rate as 1 on an NPU chart.
Experimentally, this value can be determined by determining dietary protein intake and then measuring nitrogen excretion. One formula for apparent NPU is:<ref>{{cite journal |last1=Blackburn |first1=GL |last2=Bistrian |first2=BR |last3=Maini |first3=BS |last4=Schlamm |first4=HT |last5=Smith |first5=MF |title=Nutritional and metabolic assessment of the hospitalized patient |journal=Journal of Parenteral and Enteral Nutrition |date=1977 |volume=1 |issue=1 |pages=11–22 |doi=10.1177/014860717700100101 |pmid=98649}}</ref>
:NPU = {0.16 × (24 hour protein intake in grams)} - {(24 hour urinary urea nitrogen) + 2} - {0.1 × (ideal body weight in kilograms)} / {0.16 × (24 hour protein intake in grams)}
NPU and biological value (BV) both measure nitrogen retention; the difference is that biological value is calculated from nitrogen absorbed, whereas net protein utilization is from nitrogen ingested.<ref>{{cite journal |last1=Hoffman |first1=JR |last2=Falvo |first2=MJ |title=Protein - Which is Best? |journal=Journal of Sports Science & Medicine |date=September 2004 |volume=3 |issue=3 |pages=118–30 |pmid=24482589|pmc=3905294 }}</ref> Another closely related quantity is the net postprandial protein utilization (NPPU), which is the maximum potential NPU of a dietary protein source under ideal conditions.<ref name=EFSA2012 />{{rp|p=12}}
The Protein Digestibility Corrected Amino Acid Score (PDCAAS) is a more modern rating for determining protein quality, and the current ranking standard used by the FDA.
The Digestible Indispensable Amino Acid Score (DIAAS) is a protein quality method, proposed in March 2013 by the Food and Agriculture Organization<ref>{{Cite web|date=2017-05-19|title=FAO proposes new protein quality measurement - IFT.org|url=http://www.ift.org/food-technology/daily-news/2013/march/07/fao-proposes-new-protein-quality-measurement.aspx|access-date=2020-11-03|archive-url=https://web.archive.org/web/20170519171831/http://www.ift.org/food-technology/daily-news/2013/march/07/fao-proposes-new-protein-quality-measurement.aspx|archive-date=2017-05-19}}</ref> to replace the current protein ranking standard, the Protein Digestibility Corrected Amino Acid Score (PDCAAS). The proposition is contested, however, due to lack of data.<ref>{{Cite web|title=Potential impact of the digestible indispensable amino acid score as a measure of protein quality on dietary regulations and health|url=https://www.researchgate.net/publication/323757610|access-date=2020-11-03|website=ResearchGate|language=en}}</ref>
==See also== * Protein efficiency ratio * Nitrogen balance
==References== {{reflist}}
Category:Amino acids Category:Proteins Category:Nutrition