Proteins: Are you Consuming Too Much?

Protein is a term thrown around pretty freely these days in the gym, out on a long run with your training partner, in fitness magazines, and on the internet. But, do most people even know what constituents a protein and what and how the body used protein?

Proteins are considered to be the most versatile macromolecules in living systems and proteins serve crucial functions in essentially all biological processes. Proteins function as catalysts, transport and store other molecules such as oxygen, provide mechanical support and immune protection, generate movement, transmit nerve impulses, and control growth and differentiation1. In other words, proteins have a lot of “jobs” within the human body.

Proteins are made up of long chains of amino acids. The chains of amino acids then spontaneously fold up into 3-D structures that are predetermined by the sequence of amino acids in the protein chain. It’s function is directly dependent on this unique 3-D structure. There are 20 different amino acids that vary in size, shape, and other chemical characteristics. Human can produce 10 of the 20 amino acids and the remaining 10 must be obtained through diet. These 10 amino acids that are supplied via food are called essential amino acids2. Failure to obtain enough of even one of the 10 essential amino acids results in degradation of the body’s proteins, muscles and so forth, to obtain the one amino acid that is needed2. Unlike fat and carbohydrates, the human body does not store excess amino acids for later use.

Why is protein important to the athlete? Traditionally, athletes seem to fall into two categories: those who eat too much (i.e. bodybuilders, weightlifters, and football players) and those who eat too little (i.e. runners, dancers, and triathletes)3. The current RDI for protein consumption is 0.8 kg/day (0.4 g/day) per pound of body weight. Nancy Clark, MS, RD, gives this examples in her book: a 150 lb recreational athlete who burns about 3,000 calories a day can easily consume 300-450 protein calories (75-112 g). This equates to about 1-1.5 kg of protein, which is more than the RDI of 0.8 kg. Joe Friel, MS, suggests the following protein intake4:

Training Volume (Hours/Week)

Protein (g)/day

>5

0.6-0.7

5-10

0.7-0.8

10-15

0.8-0.9

15-20

0.9-1

<20

1

To calculate your individual protein need, take the protein g/day number from above and multiple it by your weight in pounds. For example,

140 lbs X 0.9 g/lb = 126 g protein per day

Now there seems to be a “fad” going around the fitness world telling you your not consuming enough protein. Personally, I believe it’s in part due to the “feud” between the crossfit vs. endurance sport world and the emergence of the Paleo Diet. So, if people were not getting enough protein than you would think that a protein deficiency is a common problem. True protein deficiency, if you eat at least a somewhat healthy diet, is virtually non-existent, even in highly active athletes.

Many people have the perception that more protein is better. If I eat this slab of steak 3x a day then I will look like this guy!



Protein is important for cellular function and muscle repair. However, too much protein can make you sick. When too much protein is consumed, it must be broken down, primarily by the liver, by partly by the kidneys and muscles. Excess consumption overworks the liver and kidneys and can cause accumulation of toxic protein byproducts5. Amino acids, due to their chemical structure, are acidic by nature. Animal proteins are rich in sulfur-containing amino acids and when broken down release sulfuric acid5. In order for the body to buffer these harsh chemicals, bones dissolve to release buffering reagents and can lead to osteoporosis. Animal protein is also linked to heart disease, diabetes, and cancer.

Another myth about protein is that you must eat meat and dairy to obtain enough protein in your diet. That is completely untrue. Animals, including humans, can only produce half of the amino acids that compose proteins. The other half must be obtained through diet. Plants can make all 20 amino acids. Sure, not all plants have each of the amino acids, but that is why you should eat a balanced diet of a variety of fruits and vegetables. Plants are rich in proteins. Plants are so rich in protein that they meet the protein and nutritious needs of the world’s largest animals: elephants, hippopotamuses, giraffes, and cows. Humans are a faction of the size of these animals and we can deduce that plants will also easily meet our protein needs!

Eating a well balanced plant-based diet will not only meet your protein needs, but will also meet your daily fiber, vitamins, minerals, antioxidant, and phytochemical needs. See the chart here of protein contents of some common vegetables, grains, and animal products. Per percent of calories of protein, spinach has more protein than chicken, pork, salmon, and milk!


Another common misconception is the need for protein powders, shakes, and bars. I’m guilty of this. I use a protein powder in my recovery shakes after a hard workout. I use either soy or hemp protein vs. an animal based product. It is best to eat whole foods rich in protein vs. isolated protein products. Isolated products, such as protein powders, are generally highly processed by a laboratory. Be aware of what you buy and if you really need that extra protein. Can you read all the ingredients on the wrapper? Look at your protein bars, I bet you can’t read half the crap they jam pack into those “healthy” bars. I have eliminated bars from my diet because of that factor. You can easily make your own bars that meet all your nutrient needs at home in your kitchen using whole foods.

Proteins are an important aspect of your diet, but be careful that your not over-consuming protein. Protein is needed in aiding muscle recovery, but too much of it can be toxic to your body because your body cannot store it like fat and carbs. So next time you reach for you protein bar and shake after a heavy workout, make sure you ask yourself if you really need that extra protein in your diet. Chances are, if your eating a well-balanced diet then your body is already getting enough protein.

References

  1. Berg JM, Tymoczko JL, Stryer L. Biochemistry, 6th Ed. New York: WH Freeman and Co; 2007.
  2. University of Arizona. The Chemistry of Amino Acids. Available at: http://www.biology.arizona.edu/biochemistry/problem_sets/aa/aa.html. Accessed February 12, 2012.
  3. Clark N. Sport’s Nutrition Guidebook, 4th Ed. Champaign, IL: Human Kinetics; 2008.
  4. Cordain L, Friel J. The Paleo Diet For Athletes. USA: Rodale; 2005.
  5. McDougall J. Where Do You Get Your Protein? Available at: http://www.drmcdougall.com/misc/2007nl/apr/protein.htm. Accessed February 12, 2012.
Note: I am not a nutrient expert (although that is my goal in the future). I have a degree in Biochemistry and working on my Masters in Public Health. I am able to read and translate complex scientific concepts to a more reader friendly language. I researched this topic and have included a few of my own opinions. I encourage you all to do your own research and consult nutrition experts if you have any questions regarding protein and your diet. With that said, I can address any questions that you may have, but I am not an expert.
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