Proteins are the building blocks of life. They are used by your body to build muscle and other tissues. Whey protein is a fast digesting form of this important macronutrient. It is usually a mixture of beta-lactoglobulin, alpha-lactalbumin and serum albumin. It is made by separating the whey from the casein portion of complete milk protein. The casein or "curd" is generally used to make cheese, while the liquid whey that remains is separated again from lactose and other ingredients, then purified by ion exchange. Since whey is digested very quickly, it is ideal for replenishing your body after a workout. However, it may not leave you feeling full for long due to rapid gastric emptying.
Milk Proteins
Milk contains both whey and casein protein. Casein makes up approximately 80 percent of the protein found in cow's milk and supplies you with essential amino acids, carbohydrates, calcium and phosphorous. Whey protein makes up the other 20 percent of protein in milk and provides you with an abundance of branched chain amino acids, as well as bioactive ingredients like lactoferrin and immunoglobulins, both of which help to support your immune system.
Major Forms of Whey Protein
You will generally find whey protein in one of three different forms: concentrate, isolate and hydrolysate. Concentrate contains low levels of fat and cholesterol but will supply you with higher levels of bioactive compounds and carbohydrates in the form of lactose, which is simply milk sugar. Isolates have the fat and lactose removed by processing but are usually lower in the aforementioned bioactive compounds -- you will notice a slight milky taste with whey isolate. The final form is hydrolysate. This is a predigested form of whey that is partially hydrolized, which means that the molecule is split by the addition of water, so you can quickly and easily metabolize it. Hydrolysate is a more expensive form of whey protein, and you will find that it has an extremely bitter taste.
Whey vs. Casein Protein
When it comes to feeling full, casein protein is generally more optimum for satiety since it forms a gel in your stomach. This makes it very efficient in supplying nutrients. This gel slowly releases a steady stream of amino acids into your bloodstream, and it can last for several hours. This provides better nitrogen retention and use by your body. Conversely, whey protein is rapidly digested, emptying from your stomach quickly and providing a fast and large increase in plasma amino acid levels. You will find a quick but short-lived increase in protein synthesis because of this effect. Whey has a greater proportion of leucine, a powerful amino acid that promotes protein synthesis. Whey protein is far better at augmenting protein synthesis very quickly, but this positive effect is short-lived.
Optimum Use of Milk Proteins
For the best of both worlds, use both whey and casein proteins to receive the full benefits that each can provide. Whey protein helps your body rapidly increase protein synthesis, while casein helps block protein breakdown. Whey provides a fast burst of protein synthesis, while casein can help you sustain long periods of an anabolic environment for muscle growth. Because of these divergent qualities, whey and casein can be used alone and in combination to exploit their individual effects on your physiology. Because whey and casein have different but complementary effects, you may want to keep both types on hand and use them differently throughout the day. For example, you could use whey in the morning and after workouts and casein before you go to sleep at night. You can also mix whey protein into a large glass of milk. Remember, milk is approximately 80 percent casein, so combining it with whey will give you the the benefits of both. These proteins support larger increases in your lean body mass and decreases in body fat when you use them as part of a resistance training program and overall solid nutrition plan.
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