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Rating Your Protein

Several different rating systems have been developed to measure protein quality. You may find the ratings, which are usually noted on product labels, useful in differentiating among powders.

Be aware, however, that many scientists question the value of these measurements in rating protein supplements.

• Biological Value (BV): BV measures how well a protein is absorbed, used and retained by the body. The higher the BV rating, the more nitrogen (essential for muscle growth) from the protein the body retains. A BV score of 100 means all the protein is absorbed.

• Protein Efficiency Ratio (PER): This measures protein quality by assessing how much weight gain the protein promotes in laboratory animals (namely, rats). A PER score of 2.5, for example, means that 2.5 grams of weight were gained for every gram of protein consumed. The usefulness of PER to rate protein for humans is unclear.
• Protein Digestibility Corrected Amino Acid Score (PDCAAS): This measures how close the protein comes to the ideal mix of essential amino acids in humans. It factors in how quickly the protein is digested and made available to the body. The highest PDCAAS value is 1; the lowest is 0. Some scientists believe the PDCAAS rating is superior to both the BV and the PER.