Friday, January 30, 2009

Dietary protein safety and resistance exercise: what do we really know?

Lonnie M. Lowery and Lorena Devia. Dietary protein safety and resistance exercise: what do we really know? J Int Soc Sports Nutr. 2009 Jan 12;6:3.

Abstract: Resistance trainers continue to receive mixed messages about the safety of purposely seeking ample dietary protein in their quest for stimulating protein synthesis, improving performance, or maintaining health. Despite protein's lay popularity and the routinely high intakes exhibited by strength athletes, liberal and purposeful protein consumption is often maligned by "experts". University textbooks, instructors, and various forms of literature from personal training groups and athletic organizations continue to use dissuasive language surrounding dietary protein. Due to the widely known health benefits of dietary protein and a growing body of evidence on its safety profile, this is unfortunate. In response, researchers have critiqued unfounded educational messages. As a recent summarizing example, the International Society of Sports Nutrition (ISSN) Position Stand: Protein and Exercise reviewed general literature on renal and bone health. The concluding remark that "Concerns that protein intake within this range [1.4 – 2.0 g/kg body weight per day] is unhealthy are unfounded in healthy, exercising individuals." was based largely upon data from non-athletes due to "a lack of scientific evidence". Future studies were deemed necessary. This assessment is not unique in the scientific literature. Investigators continue to cite controversy, debate, and the lack of direct evidence that allows it. This review discusses the few existing safety studies done specific to athletes and calls for protein research specific to resistance trainers. Population-specific, long term data will be necessary for effective education in dietetics textbooks and from sports governing bodies.

While reading along with this review article it occurred to me just how unsure scientists in Ex Sci are of just how important protein intake is to athletes (particularly strength athletes). These studies that have been conducted are mostly on sedentary individuals which has its place of course however it is very hard to generalize and assume that everyone's body (trained or untrained) will synthesise excess protein similarly. This review also mentions ISSN's position on protein consumption and how it is unfounded as to how much protein is necessary for athletes and just exactly how much is too much. Many claims are made you can see them in all types of media without scientific support. If excessive protein intake is so dangerous than why isn't the number of bodybuilders/powerlifters death's due to renal disease or suffering from osteoporosis (since excessive protein consumtion is believed to create bone catabolism) at a preamature age? Also, is it possible that maybe its not just excessive protein consumption but perhaps it also deals with the "type" of protein consumed that have the so called detrimental effects on the body? Even though there aren't many studies that show excess protein is good or bad for athletes. According to Wolff's Law: The body will conform and adapt to the directions and stresses it is habitually exposed to. Now this law may apply to bone specifically, however, it is my thought that your body is always in survival mode. Therefore, any stress you put your body through habitually it will try to adapt and find better ways accomodate this contiuous stress. Also, I heard this from someone somewhere, if you overload your system with protein won't you force yourself into gluconeogenisis in which your body will begin using the excess protein (amino acids) for energy? I'm not sure, anyone got a response?

1 comment:

Lorena said...

Your body processes protein through gluconeogenesis only if there is not enough glucose/glycogen available. It's a survival thing, like you said.

If calories and glucose levels are adequate; then excess protein can indeed (and prefers to) be stored as fat.