The Protein Predicament
By Cameron Baker

The debate over protein requirements for both athletes and the generally active public is well documented and continues to be a highly combustible topic in the realm of health, fitness, athletics, and nutrition. Muscle magazines and weightlifters describe extreme diets that contain 45% protein. Popular, high-protein diets claim that 30% of calories should come from protein. Exercise nutrition texts state that athletes should have at the most a diet of 20% protein. Meanwhile, the American Dietetic Association, U.S. Surgeon General, and the American Medical Association all recommend that the healthiest diet is the Food Pyramid, which recommends that only 15% of daily caloric intake consist of protein. Both sides of the argument claim that the other is extreme in their recommendations and both allege to have “science” backing up their claims. However, it seems that the public just cannot seem to decipher whose “science” is more accurate, and so they continue to sit in a thick fog of conflicting information and dueling ideals, confused about appropriate and efficient protein intake to facilitate increased performance and lean muscle gains and maintenance. Let us seek to clear up some of the confusion by exploring this matter using an un-biased, scientific explanation of accurate protein ratios based on modern research and individualized application. Dr. Peter Lemon is the world’s foremost sports nutritionist specialist in this area and has researched nutrition and exercise for more than 20 years, concentrating on the role of protein and muscle growth. Utilizing his research and years of experience, as well as research conducted on the topic around the world, let us attempt to uncover the truth.

First of all, I think it is important to address protein as a substance. Proteins are large molecules called polypeptides, which are made up of repeating units of amino acids. Amino acids link together using peptide bonds to form a variety of proteins. There are about 22 amino acids that are considered biologically important. However, many more exist in the body and as supplements. Proteins are essential to the diet and important for muscle growth – they are the main component of muscle tissue. They are also needed for the growth, maintenance, and repair of cells (including muscle cells) and for the production of enzymes, hormones, and DNA. Proteins can combine with non-protein sources (conjugated proteins) to form molecules such as nucleoproteins (found in chromosomes) and lipoproteins (found in the bloodstream). Proteins make up about 74% of the dry weight of most body cells, which makes their proper ingestion critical to the athlete and exerciser alike.

For decades, athletes have viewed high-protein diets as common sense. Muscle contains protein; therefore, to build muscles, one needs to have enough of the raw material present. Once ingested, protein is broken down into amino acids, and these in turn enter the body's amino-acid “pool.” This pool is located in the body fluids and tissues, and if these sites are full, they are filtered to the liver and some cells. The body uses these amino acids as required and replaces them as they are depleted. If the amino-acid pool becomes empty and no new protein is eaten, muscle size and strength will deteriorate as the body breaks protein down to refill the pool. Protein is also 15% nitrogen. When the amino-acid pool is full and protein is eaten, the protein is broken down and stored mainly as fat. The liver converts the nitrogen into urea, and this is sent to the kidneys where it is excreted as urine. So, based on this information, we can deduce that if insufficient amino acids are present in the proverbial “pool,” then we are at risk of sacrificing muscle volume and strength; but if that same pool is full and proteins are ingested, the excess can potentially be converted to fat or urea, both of which are undesirable outcomes. So how much is too much? Or not enough?

Dr. Lemon summarizes the data collected from the combination of results from several studies (Gontzea, 1974; Tarnopolsky et al., 1988; Brouns et al., 1989; Friedman and Lemon, 1989; Meredith et al., 1989) by declaring that the research indicates that the RDA (which was determined using subjects who were essentially sedentary) is insufficient for individuals who are involved in heavy resistance or endurance training programs. Dr. Lemon goes on to show linear regression analysis to arrive at an ideal protein intake of 1.6 – 1.8 grams of protein per kilogram (roughly .73-.82 g/lb) of bodyweight per day to maintain nitrogen balance while engaging in resistance training. A recommendation of 1.2 – 1.4 grams of protein per kilogram (roughly .55-.64 g/lb) of bodyweight per day for endurance athletes was found to be ample as well. Dr. Lemon and colleagues also concluded that while athletes and exercises certainly require more protein than the RDA recommends, no marked increases in performance or muscle volume were recorded when increasing the protein above 1.8 g/kg of bodyweight, therefore, it seems that following an abnormally high protein diet poses no particularly intriguing physiological benefits.

In conclusion, although science has a long way to go before we can say that this heated topic is officially and meticulously understood, based on the years of research by Dr. Lemon and his colleagues, it seems that they’ve shed some light on the truth behind the protein debate. It looks as though the final prognosis states that you require more protein if you exercise or train regularly, but if you go overboard, you could be causing yourself grief, without any additional physical benefit. So, don’t stop drinking those protein shakes, and by all means, continue to chow down on the eggs and chicken breasts. Just know that, according to the good Dr. Lemon, after a certain level of protein and amino acids are met in your body based on your particular physical needs, that protein could wind up getting stored away as fat with the rest of the junk that we eat. In addition, when choosing protein sources, select those with a low saturated fat content such as select protein powders, chicken breast, fish, egg whites, and lean cuts of red meat (top sirloin, eye of round, bottom round, and London broil) and make sure to hydrate yourself adequately, so that any protein induced urea will be swiftly replaced with additional fluids.

References:

1. Lemon, P.W.R. "Effects of exercise on dietary protein requirements." International Journal of Sport Nutrition 8 (1998): 426-447.
2. Tarnopolsky, MA, JD MacDougall, and SA Atkinson. "Influence of protein intake and training on nitrogen balance and lean body mass." J Appl Physiol 64 (1988): 187-193.
3. Friedman, JE, and PWR Lemon. "Effects of chronic endurance exercise on the retention of dietary protein." Int J Spt Med 10 (1989): 118-123.
4. Gontzea, I, P Sutzecu, and S Dumitrache. "The influence of muscular activity on the nitrogen balance and on the need of man for protein." Nutr Rep Int 10 (1974): 35-43.
5. Brouns, F, WHM Saris, E Beckers, et al. "Metabolic changes induced by sustained exhaustive cycling and diet manipulation." Int J Sports Med 10 (1989): S49-S62.
6. Meredith, CN, MJ Zackin, WR Frontera, and WJ Evans. "Dietary protein requirements and protein metabolism in endurance-trained men." J Appl Physiol 66 (1989): 2850-2856.