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What science says about the various protein sources

One of the most well-known nutritional needs of athletes of all sports and disciplines is additional protein. Protein is the building block of all muscle tissue and ensuring the proper amount of protein will make the difference between meeting your goals and falling short. Keep your body fed with ample amounts of protein and your muscles will recover more completely and faster. A diet with insufficient protein and you will find yourself in a frustrating standstill in your training program.

Being that protein is so important, it’s no surprise that protein supplements are the #1 supplement category bar-none. More protein supplements have been sold over the past 30 years than all other sports supplements combined. Whey protein concentrate, whey protein isolate, soy protein concentrate, soy protein isolate, pea protein, casein protein, egg protein, beef protein, hydrolyzed whey protein, milk protein, rice protein and hemp protein...just to name a few. This is not to mention the food sources of protein such as fish, chicken, eggs, beef, tofu and soybeans.

So with all these different types of proteins, what is the difference? Is there a difference? If so, what should you look for in your protein supplements and high-protein foods?

For the average person and the casual exerciser, as long as you take in ample amounts of any of these proteins, which ones won't make or break anything for you. They all provide benefits and the chances you will find yourself in a depleted state if you are eating properly are remote. However, for those who strive to achieve top physical condition and get the most out of their body, choosing the right proteins at the right times can have a profound effect on the end result.

To start off, all proteins are constructed of a unique make-up of amino acids. What separates the different types of proteins is which and how much of each amino acid comprises each type of protein. When you eat any protein, your body will first disassemble the protein down into amino acids, and then reassemble the amino acids into a separate protein that is the precise make-up of what the body needs. The two aspects to take into consideration when determining protein quality are what amino acids make up the protein and how long will it take to deconstruct the protein and begin the rebuilding process. The two properties that determine this about a protein are biological value and digestibility.

The amino acids that make up a gram of pea protein are not the same as the amino acids that make up a gram of whey protein. Further, some proteins have more useful amounts of amino acids than others. The measure of the quality of each protein as it relates to how useful the protein source is to the body is called its biological value. Biological value is the proportion of absorbed protein from a food which becomes incorporated into the proteins of the organism's body. Basically, it states what percent of the protein is generally useable by the body. Animal proteins are usually higher than plant proteins. Whey, milk, and egg proteins all have extremely high biological values. Whereas wheat and some other plant proteins have very poor biological values. The list below outlines many popular proteins and their approximate biological values:

  • Whey protein concentrate: 100

  • Whole egg: 96

  • Cow milk: 87

  • Fish: 78

  • Beef: 76

  • Chicken: 75

  • Casein: 73

  • Soy: 70

  • Wheat gluten: 60

The second aspect determining the quality of a protein is the speed of digestion. However, it is important to note that quicker is not always better. For instance, immediately post workout, the faster you can get protein into your system and begin rebuilding the muscle, the better off you would be. For this, you would want a protein source that is very easily digestible such as whey protein isolate or hydrolyzed whey protein. These proteins are very fast acting and have virtually no fat or carbohydrates to slow digestion of the protein. However, if you will not be able to eat for several hours, such as before bed, during travel, meetings, etc, it is best to get a much longer acting protein, such as casein protein, as it is a very slow digesting protein that can take multiple hours to digest. A few different aspects determine how quickly your body will break down a protein. First, it comes down to basic digestion. If you eat a great deal of other foods with your protein, this will slow the digestion process and each food will compete for digestion. For instance, eating a chicken breast by itself will digest much quicker than if you eat a chicken breast with a stick of butter and a head of lettuce. Eating large amounts of fat and/or fibrous foods with your protein will prolong the digestion process significantly as they must all be digested. Similarly, beef is a chewy, often tough meat that is much more difficult for your body to digest than is a low-fat fish such as tilapia. The preparation of the protein can also impact digestion speed. For instance, beef that has gone through a blender will digest much quicker than if you were to swallow chunks of steak without chewing. All things equal however, proteins still digest at different rates simply by their make-up and how they respond to the digestion process. Below are some popular protein sources and their speed of digestion, if taken without other foods:

  • Whey protein: 40 minutes to 1 hour

  • Soy protein: 1 to 3 hours

  • Egg protein: 1.5 to 3 hours

  • Casein protein: 4 to 7 hours

As a guideline, whey protein is the fastest and casein is the slowest digesting, with all other sources falling somewhere in between. Since protein is usually taken with meals and as whole foods, determining consistent timeframes for these isn't quite possible.

Overall, whey protein is the fastest digesting and has the highest biological value, so it is no surprise that it has achieved such unmatched popularity as a protein supplement. However, whey is by no means the ideal protein for all instances as the digestion process is over so quickly, leaving the body with no external protein to use. This is why many bodybuilders have a whey supplement directly after a workout, then follow this up with a meal an hour later or so to keep the protein supply constant. Egg whites are a very high quality protein with a medium digestion time and are an excellent source of protein. Beef, chicken and fish all have a good biological value and have a medium acting digestion desirable for eating every 2.5-3 hours. Soy protein, while a little lower on the biological value scale, is a very cheap protein and still has a quality make-up that can be used for vegetarians and those looking to save money and avoid cholesterol and other properties of animal proteins. Many other plant-based proteins such as wheat, pea, etc. should generally not be used as primary sources of protein due to their poor biological values, however still provide clear benefits. So while ample protein intake is extremely important, which protein can be equally as important.

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