Net protein utilization: Difference between revisions

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{{Short description|Percentage of ingested nitrogen that is retained in the body}}

The '''net protein utilization''', or NPU, is the ratio of amino acid converted to proteins to the ratio of amino acids supplied. This figure is somewhat affected by the salvage of [[essential amino acid]]s within the body, but is profoundly affected by the level of [[essential amino acid|limiting amino acids]] within a foodstuff.

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 10 to 01 (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.

Experimentally, this value can be determined by determining dietary protein intake and then measuring nitrogen excretion. One formula for NPU is:

Certain foodstuffs, such as [[egg (food)|egg]]s or [[milk]], rate as 1 on aan NPU chart.

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))

Experimentally, this value can be determined by determining [[diet (nutrition)|diet]]ary 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))}

As a value, NPU can range from 1 to 0, with a value of 1 indicating 100% utilization of dietary nitrogen as protein and a value of 0% indication that none of the nitrogen supplied was converted to protein.

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}}

Certain foodstuffs, such as [[egg]]s or [[milk]], rate as 1 on a NPU chart.

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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.

:''Further information''

: http://www.medal.org/docs_ch12/doc_ch12.05.html

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]]