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Cornish_Celt · #1 (**permalink**) 05-23-2016, 06:47 AM

Whey protein supplements are the biggest selling nutritional supplements for bodybuilders and strength athletes; most meal plans you read suggest including a whey protein drink at least once a day. But what does a layman look for when buying a whey protein drink? There are hundreds of different types of whey protein formulas out there, so what makes one whey protein powder better than another? This article covers, with some depth, the main different types of whey protein to help you pick the perfect protein for you needs, whether you're trying to build muscle, increase strength, improve fitness or lose weight.

What's so special about whey protein anyway?
During the 1990s whey protein became very much in vogue and shoved egg protein nearly all the way out of the market place. This followed research indicating whey protein was superior when it came to protein synthesis. Reasons why whey is so good include:

Whey has a high biological value (BV – see below) which refers to how much actual protein from food is absorbed and retained by the body (Dutch Dairy Foundation, 1995).
Whey is made up of amino acids akin to that of human muscle tissue (Barth & Behnke, 1997).
Whey contains all of the nine essential amino acids (EAAs – indispensible amino acids).
Whey is high in the three branched chain amino acids (BCAAs) – leucine, isoleucine and valine, all of which are essential for muscle growth and repair, because not only are they like other amino acids in being part of the chains making up muscle protein, but they are also involved in the 'turning on' of the process of protein synthesis by upregulation.
Whey is naturally high in the amino acid glutamine, both as free form l-glutamine and as glutamine peptides. Glutamine is found in high quantities in human muscle tissue and is also the preferred source of fuel for intestinal cells.
Whey is naturally comprised of short chains peptides of amino acids which are quicker to digest than long complex proteins.
Studies have indicated that whey protein may help reduce the risk and improve disease outcome in certain cancers (Papenburg, 1990; Kennedy, 1995), improve immune function (Wong & Watson, 1995) and reduce blood pressure (Lee et al, 2007).
There are also studies looking at the effects of whey protein supplementation directly on improved athletic performance (Kerksick et al, 2006).

Digestion & Absorption of Protein
Before we look at whey protein specifically, we need to understand how the body deals with the protein that we eat. Digestion of food begins in the mouth and continues until all nutrients have been absorbed in the intestines. A number of digestive enzymes are involved in the digestion process which break down, or hydrolyse, the protein in food to short chain structures of the protein, known as oligopeptides, or the basic monomer unit of protein, i.e. amino acids. The simplest unit of proteins are amino acids of which there are 20-odd different types. Two amino acids linked together are called dipeptides, a few amino acids in a peptide chain are called oligopeptides and long chains of them are called polypeptides.

You may have been lead to believe up until now that protein (and this is the same for carbohydrates too) can only be absorbed from the intestinal lumen in their simplest monomer form, i.e. as amino acids. However, this is not the case. Amino acids are absorbed in their basic monomer form by an active sodium-dependant transport process, where they are pumped across the cell membranes and then into the blood. Also di- and oligopeptides can be taken up in their short chain form and then further broken down to free amino acids when inside the cells of the intestine rather than in the lumen. The process of this is not precisely known but is definitely unrelated to a sodium transport system and thought to be either cell enzyme-related or dependent on a chemical ion gradient.

Thus, there are two unrelated systems in operation to absorb protein (and carbohydrates); and, as these are independent, this allows a greater uptake of protein … so, you can see, if you take advantage of both methods, there will be maximum protein absorption. If you are eating a combination of food sources then both processes will be optimised naturally due to digestion processes. Also 'peptide' supplement formulas using proteins from different sources will have an advantage here as some of the peptides will be fully digested to amino acids before absorption and some will still be peptides.

Whey protein naturally contains shorter chain oligopeptides (especially in the case of whey protein hydrolysates - see later), so will be digested and absorbed very quickly, which can be advantageous when demand is high (post workout and first thing in the morning, for example).

Methods of Determining Protein Quality
Another thing we need to look at before we move onto looking at the different types of whey protein, are the different methods of analysis for assessing quality of proteins. Different methods look at how similar the amino acid profile is to human muscle tissue and how readily the protein is digested and absorbed, and from the results we can see which types of protein are the best for performance and gains.

Amino Acid Scoring (AAS) aka Chemical Scoring (CS)
This basic technique is fast, consistent, and inexpensive. It measures the EAAs present in a protein and compares the values with a reference protein. The rating of the protein being tested is based upon the most limiting EAAs.

Protein Efficiency Ratio (PER)
This measures the ability of a protein to support the growth of a weanling rat. It represents the ratio of weight gain to the amount of protein consumed. The problem with PER is that it cannot be reliably applied to growing children as the amino acid growth requirement for humans is less than those for rats. Also PER measures growth but not maintenance so it may be of limited use in determining the protein needs of adults.

Biological Value (BV)
BV measures the amount of nitrogen retained in comparison to the amount of nitrogen absorbed (Chick & Roscoe, 1930). It looks at how similar a protein source is, in respect of amino acid profile, to that of human requirements. Proteins are grouped into those of high BV (HBV), and low BV (LBV). LBV proteins includes cereal-based foods which we eat more for carbohydrate but do contain some protein.

Nitrogen Protein Utilization (NPU)
This is the ratio of the nitrogen used for tissue formation versus the amount of nitrogen digested.

The BV and the NPU methods reflect both availability and digestibility and they give a moderately accurate appraisal of maintenance needs.

Protein Digestibility-Corrected Amino Acid Scoring (PDCAAS)
This modern method for evaluating protein quality is more accurate, although the quality score of proteins measured this way does differ to that of the BV. PDCAAS takes into account the profile of EAAs of the protein in question, as well as its digestibility in humans; it is the Amino Acid Score with an added digestibility component. The PDCAAS is the current accepted measure of protein quality, and is the method adopted by the World Health Organisation / Food and Agriculture Organisation (WHO/FAO) and the US Food and Drug Administration (FDA). With PDCAAS, the proteins with a high BV score also rank quite high, but it also ranks isolated soya protein as one of the highest (WHO/FAO 1989), and casein scores higher than whey. Note that it is only isolated soya protein that has the high score; soya protein concentrate (which is used in many poor quality protein powders) does not.

Values greater than 1.0 for both the AAS and the PCDAAS are considered to indicate that the protein contains essential amino acids in excess of the human requirements. Proteins having values higher than 1.0 are rounded down to 1.0 (WHO/FAO 1989). This point is under debate as experts feel that the rounding down of high quality proteins fails to reflect the ability of the protein to complement the nutritional value of a lower quality protein.

Whey Protein Fractions
Whey is one of two principle proteins found in milk, the other being casein; there are other proteins in milk found in only tiny amounts. In cow's milk whey is about 20% of the total protein, casein nearly 80%. Casein molecules are globular, so do not dissolve easily in water, whey on the other hand is very soluble making it easy to mix.

Whey protein is actually not a single protein but a composite of a number of protein fractions. Whey can be separated into individual component proteins and each offers benefits of its own.