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Biological value

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Biological Value or BV is a common method for measuring protein quality and biological utilization rates of protein for human and animal consumption. The method relies on nitrogen retention as an indicator of protein quality. Unlike carbohydrates and fats all protein contains nitrogen. Scientists trace nitrogen as it enters the body through protein intake and measure the amount that is retained. Since protein is used in the construction of bodily cells the more protein that is retained indicates a higher level of biological utilization of the particular protein. The more nitrogen that is excreted as urine and fecal matter the less utilizable the particular kind of protein.

The number is expressed as a score with 100 being the threshold. The number progressively lowers as more is consumed,[1] while the protein's score is based on its consumption in a fasted state.

Humans

The now accepted method tested in humans for protein utilization is biological value of protein. Egg protein scored the highest number of 100 to serve as a measuring stick. Whey protein has subsequently been found to have the highest known biological value of any protein in humans.[2] Whey scored a 104 in its basic form relative to the original 100 egg scale.[3] Further testing validated, the biological value of protein for whole eggs is 100 and 104 for whey.

Animals

The Biological Value method is also used for analysis in animals such as cattle, poultry, and various laboratory animals such as rats. It was used by the poultry industry to determine which mixtures of feed were utilized most efficiently by developing chicken. Although the process remains the same, the biological values of particular proteins in humans differs from their biological values in animals due to physiological variations.[4]

Advantages

The BV is more accurate to both the PER and the PDCAAS for the measurement of protein utilization in humans.[5][6][7][8][9][verification needed]

The table below shows the Biological Value rating of various proteins.

  • Isolated Whey: 104
  • Whole Egg: 100
  • Cow’s Milk: 91
  • Egg Whites: 88
  • Fish: 83
  • Casein: 80
  • Beef: 80
  • Chicken: 79
  • Soy: 74
  • Wheat Gluten: 54
  • Kidney Beans: 49

Critics

Since the method measures only the amount that is retained in the body critics have pointed out what they perceive as a weakness of the biological value methodology.[10] Critics have pointed to research that indicates that because whey protein isolate is digested so quickly it may in fact enter the bloodstream and be converted into carbohydrates through a process called gluconeogenesis much more rapidly than was previously thought possible, so while amino acid concentrations increased with whey it was discovered that oxidation rates also increased and a steady-state metabolism where there is no change in overall protein balance is created.[11] They claim that when the human body consumes whey protein it is absorbed so rapidly that most of it is sent to the liver for oxidation. Hence they believe the reason so much is retained is that it is used for energy production not protein synthesis. This would bring into question whether the method defines which proteins are more biologically utilizable. A further critique published inthe Journal of Sports Science and Medicine, states that BV of a protein does not take into consideration several key factors that influence the digestion and interaction of protein with other foods before absorption, and that it only measures a proten's maximal potential quality and not its estimate at requirement levels.[12] Nevertheless, many athletes and Dr. Michael Colgan support BV as a reliable method for protein value.[13]

The analytical method that is universally recognized by the FAO/WHO as well as the FDA and USDA when judging the quality of protein in the human is not Biological Value but the Protein Digestibility Corrected Amino Acid Score (PDCAAS), as it was deemed superior when accurately measuring the correct relative nutritional value of animal and vegetable sources of protein in the diet. [14][15]

However, Biological Value (BV), as demonstrated by research scientists including K. Thomas as well as H. H.Mitchell, has long been considered the method of choice for estimating the nutritive value of proteins due to its relevance and accuracy.[5][6][7][8][9][verification needed]

References

  1. ^ Protein Fundamentals - Part 3 Quality Determinants by Donald G. Snyder, Ph.D. This article is sponsored by Proper Nutrition, a proprietary company
  2. ^ LE Magazine October 1998 Unlocking the Secrets to Health & Fitness.
  3. ^ Turning Up The Heat Newsletter: Evaluating the Quality of Common Protein Sources by Cheri A. Lynn.
  4. ^ Recent developments in protein quality evaluation by Dr E. Boutrif.
  5. ^ a b Methods of Estimating Protein Quality by D.M. Hegsted.
  6. ^ a b Thomas, K. Ueber die biologische Wertigkeit der stickstoff-substanzen in 1909 verschiedenen Nahrungsmitteln. Arch. Physiol., 219.
  7. ^ a b Mitchell, H.H. A method for determining the biological value of protein. 1924 J. Biol. Chem., 58, 873.
  8. ^ a b Mitchell, H.H. and G.G. Carman. The biological value of the nitrogen of mixtures 1926 of patent white flour and animal foods. J. Biol. Chem., 68, 183.
  9. ^ a b Optimum Sports Nutrition: Your Competitive Edge, A Complete Nutritional Guide For Optimizing Athletic Performance; Chapter 12. by Dr. Michael Colgan
  10. ^ Joint FAO/WHO/UNU Expert Consultation on Energy and Protein Requirements, The use of biological value of protein in evaluatiing its quality for human requirements, S.G. Srikantia, University of Mysore.
  11. ^ Testosterone Nation, The Protein Roundtable, August 24, 2000.
  12. ^ Journal of Sports Science and Medicine (2004) 3, 118-130
  13. ^ The Great Animal Versus Vegetable Protein Debate What Is The Best Protein For Muscle Growth?
  14. ^ FAO/WHO (1991) Protein Quality Evaluation Report of Joint FAO/WHO Expert Consultation, Food and Agriculture Organization of the United Nations, FAO Food and Nutrition Paper No. 51, Rome.
  15. ^ Schaafsma, G. (2000) 'The protein digestibility-corrected amino acid score. Journal of Nutrition 130, 1865S-1867S
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