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Protein Needs

Protein Needs


Proteins have many roles in the body, including structural, transport, and delivering messages throughout the body. Proteins are composed of amino acids, which serve as 'building blocks' in our bodies. The specific type of protein depends on the combination of amino acids. When we consume protein in our diet, it enters the digestive tract and is broken down into amino acids. Whole proteins cannot be absorbed and thus are broken down into smaller amino acids for absorption and transport in the body. Once in the body, these amino acids enter a 'pool' where they are stored until needed.

Our body has the ability to synthesize some amino acids, but others must be obtained from foods. There are nine 'essential' amino acids that the body is not able to synthesize and must obtained through the foods we eat. A protein source that contains all nine essential amino acids are referred to as a complete protein.

One common misconception is that animal proteins must be consumed to get adequate protein. True, animal sources contain complete proteins, but there are many other foods that also contain essential amino acids. Most American consume enough protein each day. The DRI for protein are 0.8g/kg per day.


Do athletes need more protein?

Endurance athletes do have slightly different protein needs than the average individual. Due to the catabolic nature of endurance exercise, the body goes through higher protein turnover. This means that the body is constantly breaking down and re-synthesizing protein during and after exercise.


Do I need protein during exercise?

Usually not.The body relies primarily on carbohydrate as a fuel during exercise simple carbohydrates are easily digested during endurance exercise  Digestion can be compromised during exercise, especially at higher intensities. Blood flow to the gut is shunted away to provide greater oxygenated blood flow to the working muscles. Proteins require many more steps to be broken down and absorbed across the gut. During exercise, slowed digestion means that proteins will remain in the gut often causing stomach distress. However, in prolonged endurance events lasting 10+ hours protein can be beneficial. In these types of events, the intensity of the activity is usually lower and digestion isn't compromised to the same extent. Also, during ultra endurance events the energy needs are much higher. Food sources containing protein are usually more energy dense than simple carbohydrates.


Can I have too much protein?

Trick question. It's easy to over consume protein. However, there are little to no health concerns for a healthy, active individual consuming whole food protein sources. There is some concern about the impact on the kidneys when very high levels of proteins are consumed. This amount of protein can only be obtained by consuming protein supplement, not whole food sources. For athletes consuming food sources of protein, the only major concern is the amount of protein relative to the amount of carbohydrate consumed. When protein intake is increased, usually some other nutrient intake is decreased. For most people, this nutrient is carbohydrate. Carbohydrates are very important for endurance athletes (see post on Carbohydrates & Athletes) and when carbohydrate intake is lowered as protein intake increases, fatigue and decreased performance can occur.


The bottom line is protein requirements for endurance athletes are slightly higher (1.2-1.7 g/kg per day) than average individuals (0.8 g/kg per day), however most individuals consume enough protein each day. Proteins can easily be obtained through a variety of foods, thus a supplement is not necessary. The main concern with too much protein is then carbohydrate intake is suppressed, leading to subpar performance. Also, any protein consumed in excess is stored or used for energy, which is not very cost effective.