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 [[protein]]s 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==

Experimentally, this value can be determined by determining [[diet (nutrition)|diet]]ary protein intake and then measuring [[nitrogen]] [[excretion]]. One formula for NPU is:

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.

:NPU = ((0.16 &times; (24 hour protein intake in grams)) - ((24 hour urinary [[urea]] nitrogen) + 2) - (0.1 &times; ([[ideal body weight]] in kilograms))) / (0.16 &times; (24 hour protein intake in grams))

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

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 an indication that none of the nitrogen supplied was converted to protein.

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>

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

:NPU = (({0.16 &times;× (24 hour protein intake in grams))} - ({(24 hour urinary [[urea]] nitrogen) + 2)} - ({0.1 &times;× ([[ideal body weight]] in kilograms)))} / ({0.16 &times;× (24 hour protein intake in grams))}

The [[PDCAAS|Protein Digestibility Corrected Amino Acid Score]] is a more modern rating for determining protein quality.

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 [[PDCAAS|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==

* [[Biological value]]

* [[Protein efficiency ratio]]

* [[Nitrogen balance]]

* [[Protein Digestibility Corrected Amino Acid Score]]

==References==

{{reflist}}

*Suzanne Nelson et al. Ad Libitum. H20 NaC{{full}}

[[Category:Amino acids]]

[[Category:Proteins]]

[[Category:Nutrition]]