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 acids within the body, but is profoundly affected by the level of limiting amino acids within a foodstuff.
Experimentally, this value can be determined by determining dietary protein intake and then measuring nitrogen excretion. One formula for NPU is:
- 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 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.
The Protein Digestibility Corrected Amino Acid Score is a more modern rating for determining protein quality.
Famous quotes containing the words net and/or protein:
“The history of literature—take the net result of Tiraboshi, Warton, or Schlegel,—is a sum of a very few ideas, and of very few original tales,—all the rest being variation of these.”
—Ralph Waldo Emerson (1803–1882)
“Firm-style bean curd insoles cushion feet, absorb perspiration and provide more protein than meat or fish innersoles of twice the weight. Tofu compresses with use, becoming more pungent and flavorful. May be removed when not in use to dry or marinate. Innersoles are ready to eat after 1,200 miles of wear. Each pair provides adult protein requirement for 2 meals. Insoles are sized large to allow for snacks. Recipe booklet included.”
—Alfred Gingold, U.S. humorist. Items From Our Catalogue, “Tofu Innersoles,” Avon Books (1982)