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.

Lactoferrin (LF)
Lactoferrin is an iron-binding whey protein and may increase iron absorption and transport. LF is added to infant formulas to make a protein composition similar to that of human milk. It is also an anti-microbial and anti-viral agent; LF may inhibit a diverse range of organisms, including bacteria, yeast, fungi, parasitic protozoa, E. coli, HIV, herpes viruses and hepatitis C. LF may also have some prebiotic activity, stimulating growth of beneficial bacteria in the intestinal tract. Animal studies suggest it may decrease bone breakdown, helping sustain bone density.

Glycomacropeptide (GMP)
Glycomacropeptide is a casein-derived peptide found in cheese whey with anti-microbial capabilities. GMP is missing the amino acid phenylalanine, which makes it a useful protein for individuals with the disease phenylketonuria (PKU).

Immunoglobulins
Whey protein contains some of the immunoglobulins, namely IgG1, IgG2, IgA and IgM. These are involved in the immune system and have anti-microbial activity and may neutralize toxins and viruses. Substantial research is currently under way to determine the potential application of milk antibodies in the prevention or treatment of microbial diseases and conditions in humans.

Alpha-lactalbumin (Alpha-lac)
Alpha-lac accounts for about 25% of total whey protein. Added to infant formulas, it creates a protein profile more similar to human milk. It is also added to some bodybuilding protein supplements and it is easily digestible.

Beta-lactoglobulin (Beta-lac)
Beta-lac represents about 50% of the total whey protein content in bovine milk. It is responsible for some of the functional properties of whey, such as water-binding.

Lactoperoxidase (LP)
This is a secretory enzyme, and it acts as a natural microbial agent with potential use in dental products to reduce caries. Adding LP to milk can inhibit bacterial growth and extend shelf life.

Bovine Serum Albumin Peptides
Found only in minute amounts, but they are rich in precursors for the major in vivo antioxidant glutathione (GSH).

The Production and Different Types of Whey Protein
Originally whey was a by-product in the manufacture of cheese, and was discarded. In its original form whey is a liquid, and it takes several stages of processing, before we get whey protein powder that's primarily protein. As a rule of thumb, the more processing, the higher the concentration of protein in whey.

There are a few manufacturing processes involved in the production of different types of whey:

Ultrafiltration
This process uses pressure and a porous membrane to separate fat and lactose from whey. Varying degrees of pressure are used to force the liquid protein through a porous membrane, which has only minute holes allowing only water, soluble components and smaller minerals and organic molecules through. Larger proteins can't pass through and are collected for further processing.

Cross-Flow Microfiltration (CFM)
A low temperature process using ceramic filters. These filters retain the majority of the beneficial whey protein fragments. CFM removes large fat globules, leaving total fat less than 1%.

Ion-Exchange (IE)
This is a method that uses ionically charged clay resins to bind with the protein and separate it from other whey constituents. Chemicals to adjust the pH are also used, such as sodium hydroxide and hydrochloric acid. This produces the purest form of whey protein isolate, washing free impurities such as lactose, minerals and fat. One drawback is that some of the beneficial whey protein fractions may be lost.

Industrial Chromatography
This is more expensive and in-depth than IE and produces almost pure forms of individual protein fractions.

Hydrolysis
Hydrolysis is separation of already pure protein into oligopeptides. The structure of the protein is broken and bonds between amino acids in the polypeptide chain are hydrolysed, allowing the protein to me more easily digested and absorbed. This effectively makes the protein already 'pre-digested'.

There are three main different classes of whey protein available:

Whey Protein Concentrate (WPC):
The first filtration process in the production of whey protein is ultrafiltration, where the protein is separated from the fat and lactose in milk through a porous membrane. Whey concentrate is generally classed as the most basic of the whey protein types, though in itself the protein concentration can vary considerably, from 35-85% - so there's a huge variance in the quality of different WPC powders. This depends on the extent of the filtering. Most WPC which are popular on the market are generally 68-80%. Although WPC isn't the purest protein because it's less processed, if the brand is good, it can still be a very high quality protein powder, just with the presence of some fat and carbohydrate and will be perfectly adequate for a recreational trainer.

One benefit of WPC is that the less processing, means that most of the beneficial whey protein fractions are still undamaged. Also it's generally less expensive than whey protein isolate or hydrolysate.

Whey Protein Isolate (WPI):
WPI has undergone even more processing; therefore it's purer than WPC. The additions may be longer filtering or ion-exchange chromatography. This gives formulas which are 85-95% protein, and WPI can be a good choice for a strict diet if you're wanting a low fat and/or carb intake. It would also be a better choice for diabetics and for those with more severe lactose intolerance. WPI also has a higher BV than WPC.

Whey Protein Hydrolysate (WPH):
If either WPC or WPI go through a hydrolysis process, the longer protein chains are broken down into even smaller peptides. Whey is already made up of fairly short polypeptides, but hydrolysis makes these even smaller and is like 'pre-digesting' the protein, making it semi-elemental. (Semi-elemental means that a macronutrient, i.e. protein, carbohydrate and fat, is part digested and consists of short chains of that nutrient, in this case oligopeptides which are more easily digested than long chain polypeptides). This is even easier on the digestive system and there is a higher absorption percentage. WPH can have as much as 50% of the amino acid bonds broken during hydrolysis. Taste can be a good indicator of whether the product you're using has a higher amount of hydrolysed bonds, as protein powders with smaller protein fragments tend to have a bitter flavour.

WPH is the best post-workout protein around, but it is expensive. Hydrolysed proteins generally taste foul, so here are some tips to consider when looking for a hydrolysed product:

1. The product should indicate the degree of hydrolysis applied to the protein. The higher the percentage the more hydrolysis that has taken place and the more bitter it will taste. If the product does not detail this, then ask the manufacturer.
2. Packaging should display a table listing the molecular weights of the peptides themselves. These will be measured in Daltons. Usually the percentage of peptides are listed, e.g. MW 20,000-40,000 Daltons 40%.
3. WPH contains virtually no biologically active protein fractions. All of the fractions are destroyed during the process.
4. If you see any claims for BV higher than 104, be careful as this is not possible!

In theory WPH is the ultimate protein to take immediately after a workout, as your body absorbs it very quickly simply because it is more digested than other whey. As there are still oligopeptide chains though, it will still utilise both methods of absorbing protein in the intestine. However, the fact that there are virtually no biologically active protein fractions could be viewed as a drawback of WPH. So, for this reason only use WPH pre- or post workout. Use other types of whey at other times of the day.

WPH is also used clinically in enteral tube feeds. It is used in this instance not because it is absorbed more easily, but because it is hypoallergenic. Some critically ill people and babies are allergic to certain fractions like beta-lac; a way round this is to hydrolyse the protein, thus breaking down the allergen part of the protein into peptides.

Absorption Rates of Protein Supplements
Below are the approximate absorption rates of the main protein supplements. Note that these are when the product is taken when mixed only with water and consumed on an empty stomach, if other constituents are also ingested this may affect the timings:

• WPH: 10 – 30 mins
• Microfiltered WPI: 30 mins – 1 hr
• Ion Exchanged WPI: 30 mins – 1 hr
• Ultrafiltered WPC: 1 - 1.5 hrs
• Egg Albumin: 1.5 - 2.5 hrs
• Micellar Casein: 2.5 hrs – 4 hrs

Whey Protein and Blood Insulin Regulation
In addition to providing protein, whey protein has also been linked to raising blood insulin levels. Whey has been show to increase the secretion of insulin from the beta cells of the pancreas; insulin is an anabolic hormone. Insulin is not only involved in carbohydrate metabolism, and pushes glucose into muscle cells, but it also helps shunt protein into muscle. Therefore by consuming a whey protein formula, not only are you are increasing the amount of protein which is available for muscle cells, but you are also aiding the mechanism in order to shunt it in.

The addition of WPH to a carbohydrate drink exerts an even greater insulin response than that of carbohydrate alone or from that of a WPI formula (Calbet & MacLean, 2002). WPH has been shown to augment the maximal insulin concentration by a mechanism that is unrelated to gastric emptying (Power et al, 2008). It is the essential amino acids which facilitate the secretion of insulin from the beta cells (Floyd et al, 1966; Van Loon et al, 2000). Whey protein is composed of between 40-50% EAAs and is considered a rich source of these insulin regulatory amino acids, so making them more bioavailable, as in the case of WPH, maybe be the reason why there is better secretion of insulin from the beta cells. This is independent from the rate that amino acids/protein leave the stomach. The key amino acid is believed to be phenylalanine, though the exact mechanism is not wholly understood.

Choosing your Protein Powder
With the huge range of different protein powders and brands available on supplement store shelves, it can be confusing. You have to consider the aspects which are important to you as an individual. Price may be the overwhelming factor, and if this is the case, WPC will be perfectly adequate and does the job very well. Convenience may be more of an issue for you, if so, look at the range of ready-to-drink formulas available (though be aware these may have additives to improve shelf life and some of the beneficial whey fractions may have been destroyed). If flavour is important to you, then simply find which of the reputable brands sits best with your palate. Mixability and texture may be factors influencing your choice – do you prefer a thick shake or a thinner consistency one?

If you're supplementing with whey protein as part of a dietary regimen to help control your weight, then including one or two shakes per day of a good quality concentrate or isolate may be useful. Remember protein is both more satiating (hunger inhibiting) and thermogenic (raising body temperature, i.e. fat burning) than the other macronutrients – both important factors when on a diet.

Whey is great and was undoubtedly a revolution in bodybuilding nutrition. However, other proteins like casein, soya, egg and meat all have their own benefits. Protein blends of two, three or more different proteins can be useful to structure correctly into your diet. Casein is a slowly digested and absorbed protein providing a steady influx of amino acids for up to a few hours, ideal to prevent muscle protein breakdown during periods of fasting, like overnight. Like whey, soya protein is available in concentrate and isolate forms, and is digested and absorbed as fast and as efficiently as whey; it is also rich in glutamine and BCAAs, aswell as antioxidants. Egg white protein is one of the highest quality proteins available and has trace amounts of fat and carbs.

There are a lot of factors which come into play in our quest to grow bigger muscles, so in this grand scheme of things, does having the protein being absorbed very slightly quicker or having a few milligrams more of one amino acid really make that much difference? Especially when you compare this to having a balanced, healthy diet and hard consistent training? We all know a good healthy diet with a good protein intake from 'real food' is far more important than any protein powder. Taking this very important point into consideration, for the most of us wanting to gain muscle and strength whether it be competitively or recreationally to shape up, then a good quality whey concentrate powder will be fine (look for one which is over 75% protein, though).

If you have a larger budget and feel that using WPH would be of benefit post-workout, then the evidence does indicate some mileage in this, but you only need a small amount and only at this time.

Think of WPI as a protein that has been filtered or cleaned a bit more. Some people do find that some WPC upset their stomachs, but they are fine with WPI; obviously this is an important consideration. I once heard this analogy: Using whey isolate is like filling a family car with Formula 1 type petrol - it won't improve the performance of it. Use the money saved to buy some good quality food. There's a lot of truth in this.