Going back around 10 years, Milk and egg was considered the best protein supplement to use. The old protein 90+ powders were also best sellers, made from caseins (milk proteins). Then along came Whey protein, a new super duper protein superior to all others!! With statements such as "our whey protein has a BV of 157!" - different companies marketing there whey products differently, but all stating that whey is the best protein! Well lets take a look at how these companies define and measure the quality of a protein, and how that relates to its muscle building properties. You may have seen different measures of the quality of a protein, such things as BV, NPU, PER, or PDCAA. I will briefly touch on each of these.
First off we have BV (Biological Value). This is quite an old measure, and using this different variations of whey protein powder (concentrates and isolates) can score well over 100, which at one time was the highest possible score for a protein! Basically what BV tells us is the percentage of protein that your body has absorbed from the amount of protein you ingested (% of absorbed Nitrogen retained in the body). This gives an indication of how much of the protein that is consumed actually remains within the body to promote protein synthesis.
Secondly we have NPU (Net Protein Utilisation). NPU, is the ratio of amino acids converted in to proteins, compared to the ratio of amino acids supplied throughout the day. NPU is a useful index for evaluating both digestive and metabolic protein utilization, 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 the food that you have ingested. What I mean by limiting amino acid is, any amino acid which is classed as an essential amino acid, i.e. one that cannot be manufactured in the body from scratch.
Thirdly we have PER (Protein Efficiency Ratio), this has now been replaced by a more effective measure called PDCAAS (Protein Digestibility Amino Acid Score). PDCAAS was developed by the Food and Agriculture Organization (FAO) to compare the quality of different proteins based on amino acid requirements necessary for humans. A protein receives the highest value (1.0) by containing all the essential amino acids required by our bodies. The idea is that all the protein needs of your body will be met, if your diet provides you with enough of the essential amino acids. It first scores a protein based on its amino acid content and then adjusts it to account for the food's digestibility. Corrections for digestibility of protein are applied to give a protein-quality rating such that's much closer to reality for human metabolism. The PDCAAS is based on the amino acid needs of children ages 2-5, since this is the group that needs the greatest amount of amino acid consumption. By using a 2-5 year old child's needs as a base, it is assured to exceed the amino acid needs of everyone since your needs decrease as you get older
Now you have a brief knowledge of the most popular protein quality measures, that is what they are and what they measure. So the next time you buy a tub of protein, are you going to get clever and start quoting PDCAAS values etc?? Well what I suggest is to forget all these fancy values, and simply look at the contents!! We already know that Whey protein is a complete protein, and will score well on all of these measures!! So do we just stick with good old whey protein? That all depends on how we aim to use it - post workout or as a meal replacement. First off there are several different types of whey protein. For example Isolate, concentrate, hydrosylate etc etc. The best whey protein by far is whey isolate, not only does it have the best amino acid profile, it has many other properties. Proteins are constructed of chains of amino acids all bonded together, depending on the number of chains (peptides) and structural shape, they have different classifications - Secondary, tertiary, quaternary etc. Without getting too complicated, in short not all protein structures and farctions are the same. Some can have immune system boosting properties amongst other properties. Whey protein isolate has many special protein fractions that cannot be found in other proteins. Therefore Whey isolate is a must post workout or in addition to a solid food protein meal.
However the best protein powders used for meal replacements will have a variety of protein sources. This ensures that you get a wider amino acid spectrum, and hence more complete proteins, it also helps supply your body with a steady supply of aminos, compared to most whey proteins that give you a massive influx of aminos (known as anabolic proteins) most of which will be oxidised and not used in protein synthesis unless used in the "magic" window of opportunity post workout. Hence combining whey protein (or any other proteins for that matter) with other proteins, such as egg white and micellular caseins, you are creating a designer protein far superior to any one single protein source.