How Much Protein? Going by the Numbers

General protein requirements:

The recommended amount of protein for adults is 0.8g/kg or 0.36g/pound.  This is the equivalent of 10-15% of your daily caloric intake.  It is important to note that these numbers are relevant if at least 2/3 of the protein comes from animal sources.

Protein requirements for athletes:

• Endurance Athletes - 0.8-1.4g/kg.  The amount could increase towards the higher number if protein is being used as a fuel source. 
• Resistance-trained Athletes - 1.5-2g/kg.  This is always dependent upon the athlete, the type of protein consumed, and the amount of calories ingested vs. the amount expended.

Concerns:

• Excessively high intakes (greater than 4g/kg) are not advisable, especially for those who have impaired renal function, low calcium intake, or low fluid intake.
• Staying in these protein ranges also keeps nitrogen in balance.

All data from this post is from the NSCA Essentials of Strength and Conditioning textbook, Chapter 10, pages 206-208)

Protein and Bone Health

Does protein help your bones stay strong, or does it hurt them?  There research in this article has visits both sides of that question.  The key that I took from reading this is that a high amount of protein intake leads to an increase the excretion of calcium through the urine.  So to maintain bone health while consuming high amounts of protein, you should also be getting enough calcium in the diet as well.

http://www.ajcn.org/content/early/2009/10/28/ajcn.2009.28812.full.pdf

Which type of protein is right for you?

There are a lot of different types of proteins to consume.  This article from the NSCA illustrates the differences between these proteins; I will highlight a few.

Whole Foods-  A great source of dietary protein, can be used post-exercise without taking on any extra calories of a protein shake, also making it a cost-effective decision.  They take longer to digest, which keeps a steady rate of AA's going to the muscle.  These foods usually take preparation and time to cook, but it's a better option than consuming processed foods like hot dogs, canned foods, and microwavable meals.  Fish, beef, chicken, and eggs are great sources of proteins that also contain many EAAs and other micronutrients.  Milk contains both whey and casein proteins.  It can facilitate post-workout glycogen restoration.  Milk is rich in EAAs and is much cheaper than protein powders.

Whey Protein- Isolated from milk, and has a quick assimilation rate; can be rapidly absorbed by the body.

• Whey Concentrate - Least processed and contains less available protein.
• Whey Isoloate - Processed more to increase the amount of protein and also to remove impurities.
• Hydrolyzed Whey - Predigested by enzymes, breaking the protein molecules into smaller peptides. This allows the protein to rapidly enter the bloodstream.

 Because of the rapid rate of assimilation, whey doesn't need to consumed in such high quantities.  If too much is ingested, it will be converted to fat or excreted through the urine; sounds like a waste of money to me.

Casein protein- The main protein found in milk; releases amino acids into the bloodstream much slower than whey, keeping a balanced flow of AA's. Some companies are now selling a casein/whey protein mixture to offer both slow and fast acting amino acids.


Soy Protein- A plant protein (not derived from milk).  It contains antioxidants called "isoflavones." These antioxidants are good for the body, however have been suggested to have the negative effect of increasing the estrogen content in men.  This effect is undesirable in most men (especially those who resistance train), when most who are resistance training want to utilize (and increase) the amount of testosterone in their bodies to maximize performance.  When it comes to muscle repair, whey and casein are better, but soy protein still has some promise in regards to antioxidants.

Amino Acid Supplements- There are 9 essential amino acids (cannot be synthesized by the body) and 11 non essential amino acids (can be synthesized by the body).  Proteins provide many of these, with whey protein providing many of the essentials.  AA supplementation (with or without another source of protein) may be as beneficial as using a different type of protein after exercise.  The supplements that offer the most EAA's will be the best for tissue repair.

http://journals.lww.com/nsca-scj/Fulltext/2009/02000/The_Post_Workout_Protein_Puzzle__Which_Protein.4.aspx

Protein for...Endurance Athletes??

It is a common practice for most resistance-trained athletes, and those who participate in quick, vigorous bouts of exercise to consume protein after their workout to promote tissue repair.  Recent research shows that there may similar benefits for endurance athletes as well.  During an endurance performance, or an event that takes about 90 minutes to complete, athletes should consume carbohydrates to replenish glycogen that is lost during exercise, to maintain pace.  Though the research is limited for now,  recent studies have shown that there is no benefit in taking protein with CHO during endurance performance.  However, since protein promotes the healing of tissues and the replenishing of muscle glycogen, ingesting 10-20 grams of protein after endurance training will have these results, which may also increase the athlete's ability to adapt to their training.  Some studies show that performance may be improved with added protein but the reason is thought to be from an increase in energy intake.  An excess of CHO (1.2g/kg) may actually negate the need for added protein, but the protein may also assist with glycogen synthesis if there is an insufficient amount of CHO ingested during recovery.

I find this article interesting because I ran cross country for years and never thought that I could help with my recovery by ingesting protein in recovery.  Most in-season cross country runners eat a diet that is largely made up of more carbs and fats than are usually recommended.

http://www.gssiweb.com/Article_Detail.aspx?articleID=719

Common Misconceptions

Here's a link to an article that discusses a topic that we have already known about: the misconceptions about protein supplementation among high school athletes. Companies cater to teens with promises of getting huge and obtaining an "8 pack" but they might be providing false information to promote and sell their product. This type of marketing can give people the wrong idea about the product, and they may be putting harmful substances in their bodies.

http://journals.lww.com/nsca-jscr/Fulltext/2008/07000/Protein_Supplement_Users_Among_High_School.14.aspx

Protein and Resistance Training do what to BMD?

http://journals.lww.com/nsca-jscr/Abstract/2007/11000/The_Combined_Effects_of_Protein_Intake_and.37.aspx

Protein Supplements and Exercise

Hello reader(s), I find this article interesting because it actually talks about what happens when we supplement protein and maintain a regular exercise program. More of my opinion on the matter is soon to come.http://www.ajcn.org/cgi/content/abstract/72/2/551S