Sunday, February 24, 2013

Protein Intake: Past and Current Research

We have all seen the ads on TV and in magazines for protein powders, protein bars and other high protein drinks, advertised as essentials that everyone should add to their diet in order to have ripped abs and big muscles, but is that extra protein actually helping us out? Are our bodies utilizing all the protein we take in?

In a study performed in 2008 by Moore et al., it was found that muscle and albumin protein synthesis were maximally stimulated at a dose of 20 grams of protein following resistance exercise. Increasing doses of protein following resistance training were shown to have no further increase in mps or aps, and protein in excess of this amount was found to be lost to oxidation. In another study performed in 2009, focusing on young and elderly subjects, by Symons et al., a comparison of 30 grams of protein consumption and 90 grams was observed. In this study it was shown that the muscle protein synthesis was increased by 50% with a 30 gram does of protein and that no further increase in muscle protein synthesis was observed at higher doses. Based on the results from these two studies it has widely been accepted that no further benefit would be seen in a practical setting in which individuals were ingesting more than 20 to 30 grams of protein per meal. However, more recent studies have contradicted this widely held dogma.

While muscle protein synthesis does appear to reach its upper limits approaching 20-30 grams of protein, studies have shown that protein intake serves a larger role inside the body than just to build muscles. In a review written by Drs. Deutz and Wolfe, the two examine why this long held belief that individuals utilizing the 20-30 gram intake range per meal might be misguided. In their article, Wolfe and Deutz discuss the overall affect of protein ingestion as it relates to anabolism (the synthesis of complex molecules from simpler ones). In their article they explain that the anabolic response is measured as a function of both protein synthesis and breakdown and that projections of anabolism compared to protein intake have no maximal limit incontrast with the long held belief of ingesting at most 30 grams of protein per meal.

While these seperate indications for protein intake may be contradictory we can take away a few things from these observations. While earlier research performed by Moore et al. and Symons et al. show a maximal muscle protein synthesis at 20-30 grams of protein intake a meal, Wolfe and Deutsz suggest that this figure may not take into account a realistic view of metabolism of an individual in their daily life.

Remember that protein is not used just for muscle synthesis. It also plays vital roles in several other functions of your body. Consumption of protein has also been found to increase satiety. As with all diet changes, be sure to consult with a healthcare professional, especially if you have any pre-existing health conditions.

To Your Health,
Ryan Hasapes 

1.Deutz NE, Wolfe RR. Is there a maximal anabolic response to protein intake with a meal?. Clinical Nutrition. 2012 November 27

2.Symons TB, Sheffield-Moore M, Wolfe RR, Paddon-Jones D. A moderate serving of high-quality protein maximally stimulates skeletal muscle protein synthesis in young and elderly subjects. J Am Diet Assoc. 2009 Sep;109(9):1582-6.

3.Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, Prior T, Tarnopolsky MA, Phillips SM. Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr. 2009 Jan;89(1):161-8.

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