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effectiveness of protein supplements in advancing muscle growth
By: Michael Springer
October 5, 2009
For many years, increased protein intake has been associated with increased muscle mass and strength. This is especially important for athletes as well as the frail elderly who experience muscle loss due to their old age. For the elderly, it is a matter of increasing the number of healthy years each individual has left; for athletes, it is a matter of increasing the effectiveness of each workout. The majority of individuals carryout a protein supplement program with minimal knowledge regarding the science and mechanism behind it.
Since muscle is composed of proteins, higher intake of protein during resistance exercise will contribute to the rebuilding of muscle, resulting in larger and stronger muscles. While this makes sense logically, this is not sufficient evidence to prove the effectiveness of protein supplements.
What claims are made about
The biggest claim made by the majority of commercial protein supplement providers is the dramatic increase in muscle mass immediately following the use of their product (http://www.gnc.com/category/index.jsp?categoryId=3593187). This increase in muscle mass is claimed to be associated with an increase in metabolism and therefore the burning of more calories. Along with this, protein is claimed to “help increase lean muscle mass”, “prevent cancer”, “support healthy immune system”, and “prevent muscle wastage” along with the claim that there are no adverse effects associated with excess protein (http://www.proteinsupplementguide.com/). Another site claims that “taking double doses won’t hurt, it just costs more” (http://www.vitalady.com/comparison.htm). Claiming something such as this can be extremely detrimental to the public as this would lead them to believe that there is no limit on how much protein a person can have. Some these claims contradict other products with testimonials claiming that “These protein shakes and puddings are designed to promote and enhance the fat burning process. 1 gram of protein will burn 30 calories, therefore by consuming just 1 serving, you can burn 450 calories. It's like throwing gasoline on a fire...” (http://www.bodyandhealthessentials.com/protein_shakes.htm).
Most protein supplement users are on a regular exercise program and use protein to compliment these programs. This can cause misleading evidence since the majority of results seen by athletes can now be correlated with protein use. It is important to be skeptical as correlation does not imply causation. Weight loss, increased metabolism, and a stronger immune system have all been associated with increased physical activity, so it would be impossible to distinguish between the two in such a given situation. Only a few of these commercial sites contribute the effectiveness of protein to a regular exercise program, most of them attribute all the benefits seen from protein ingestion directly to the protein itself regardless of physical activity levels. Most of the websites used for promoting the usage of protein supplements rely heavily on individual testimonials that don’t discuss other factors contributing to their results.
What does the research prove?
The dietary requirements for protein intake vary depending on the needs of each individual but typically range from 34-56g/day (http://www.health.gov/dietaryguidelines/dga2005/report/HTML/D1_Tables.htm). Lemon (2000) standardized these needs to say that an individual’s recommended daily allowance is .8 grams of protein/kg of body mass. Research compiled in this review suggests that .8 g/kg is for sedentary individuals, while those engaged in physical activity require over twice as much (1.6-1.8 g/kg) on a daily basis. Nitrogen balance in the blood has long since been associated with protein requirements of the body; Lemon compiled the results of five different studies measuring nitrogen balance, all showing this significant increase in protein requirements for physically active individuals. These results alone suggest that, for physically active people, standard dietary protein would not be enough to satisfy the needs of the body; protein supplements would be required. The mechanism responsible for this increased need is explained through a comprehensive review by Miyazaki (2009). Miyazaki proposes that mechanical stretch/tension on muscles leads to the activation of the mammalian target of rapamycin (mTOR) pathway which is known to be necessary for skeletal muscle growth. Along with the activation by mechanical stretch, mTOR activity is also regulated by the availability of amino acids; therefore, as mTOR is activated, it requires more protein for the growth of skeletal muscle, and excess amino acids in the blood stream would further increase the activity of mTOR, resulting in even more skeletal muscle growth. Increasing your protein intake to compensate for physical activity may be necessary, though, as the body breaks down proteins, the concentration of free amino acids in the blood increase so excess protein would elevate these amino acid levels. Along with this, most commercial protein supplements include a variety of free amino acids. Garlick (2004) compiled a list of the adverse effects associated with an excess of amino acids in the blood stream. These effects include damage to various brain regions, depression, nausea, and the depression of food intake. These results contradict the claim that no harm can come from excess protein intake, as there is sufficient evidence to caution against excessive use of protein.
The majority of the research has found that, with protein supplementation, there is a statistically significant increase in muscle mass and strength among individuals participating in resistance exercise (RE) regardless of age. This increase in muscle mass will, however, only occur under certain conditions. The conditions under which protein is ingested are crucial for its effectiveness, which contradict the assumption along with commercial claims that simple ingestion of protein will result in increases muscle mass and strength. The biggest component affecting the effectiveness of protein is the quality of RE. Without RE, protein supplementation will increase the free amino acid content of the blood, which can be toxic, without stimulating any significant muscle growth. One study found that increased protein intake will only have an effect if the protein is taken within one hour of resistance exercise (Cribb et. al., 2006). In this single-blind study, two randomized groups were created: one ingested protein an hour before and after resistance exercise while the other group ingested the same amount of protein both in the morning and evening (hours before and after RE). After 10 weeks of supervised RE training, 1 repetition maximum, muscle size and muscle composition were compared to the initial values. The study found that RE in conjunction with protein supplement taken within a hour of RE lead to a significant increase in muscle mass compared to ingestion hours before and after. It can be concluded that the effects of protein ingestion degrade with time from RE; however, this study did not consider a continual time frame so no conclusions can be drawn as to how the effectiveness of protein intake degrades with time.
While it is important to ingest protein within an hour of RE, it does not matter whether the protein is ingested before or after the exercise (Tipton et. al., 2007). In this study, one group ingested whey protein before RE and the other group ingested the same amount of whey protein after RE. The focus of this study was on systemic concentrations of various substances but muscle strength and composition were also measured. Between the two groups, there were no statistically significant differences in muscle mass, strength, or amino acid concentration in the blood. It has also been shown that, there is no significant difference in muscle mass increase regarding the type of protein ingested (Lemon, 2000). It is known that whey protein is more readily absorbed by the body; however, Lemon concludes that there is no difference in muscle mass increase when compared with other types of protein supplements (i.e. casein, soy, maltodextrin). These results, however, are based on the conclusions made by a previous study conducted by Lemon, with no other supporting evidence. While Lemon found that there is no difference in muscle mass increase, there are other issues that need to be considered regarding their effects on the body that weren’t considered in this review, such as elevated amino acid content and other physiological effects. The major motivation for protein supplementation is to increase the efficiency of every workout; based on the conclusion of three separate studies, Lemon (2000) reports that in order to maximize the effectiveness of a RE even further, protein must be taken in conjunction with creatine.
The most clinical benefit of protein supplementation is to reverse the effects of the aging process on muscle loss. Bonnefoy (2003) specifically studied how protein ingested contributed to the progression of muscle loss in the frail elderly during a light RE program. With the mean age of 83, this study randomized the subjects into four groups: supplement with RE, placebo with RE, supplement with alternative memory exercise, and placebo with alternative memory exercise. Within the RE groups, there was a 57% increase in muscular strength compared to the memory groups; however, there was no significant difference between the RE groups. These results suggest that, while protein supplementation has a profound effect on physically active individuals, it is not enough to counteract the degradation of muscle in old age. It is important, though, for elderly individuals to participate in some level of RE as this has the most dramatic effect in counteracting muscle loss. Bonnefoy also noted that ingestion of protein without RE led to an increase in Body Fat, suggesting that the increased caloric intake associate with the protein supplements could have the opposite desired effect in sedentary individuals. While these conclusions are substantial, Bonnefoy addresses the concern that the compliance rate of this study was relatively low, which limited the number of subjects that could be measured and therefore is cautious about over generalizing the results found.
the evidence, what conclusions can be made?
The major commercial claim of protein increasing lean body mass has been sufficiently supported by scientific research and is a valid claim. The introduction of tension on skeletal muscle activates muscle growth which consumes more protein, causing the body to require more. The other benefits of protein, such as cancer prevention and weight loss are not supported by the scientific literature. In this case, the claim did not consider the external factors, such as RE, in the effect of the protein. A sedentary individual consuming protein supplements would see an increase in body mass, though this would not be lean body mass which would be caused by the increased caloric intake and not the protein itself. The most harmful claim that has been made is the safety of protein and the inability of a person to take too much. Especially in today’s market, protein supplements are full of free amino acids along with the protein and especially high concentrations of these amino acids can be detrimental to a person’s health.
From a personal standpoint, the evidence from the scientific research is sufficient to convince me to take protein supplement in conjunction with a high level RE program to build lean body mass.
1. Bonnefoy, M., Cornu, C., Normand, S., Boutitie, F., Bugnard, F., Rahmani, A., et al. (2003). The effects of exercise and protein-energy supplements on body composition and muscle function in frail elderly individuals: a long-term controlled randomised study. British Journal of Nutrition , 731-738.
2. Cribb, P. J., & Hayes, A. (2006). Effects of Supplements Timing an resistance Exercise on Skeletal Muscle Hypertrophy. Medicine and Science in Sports & Exercise , 1918-1925.
3. Garlick, P. J. (2004). The Nature of Human Hazards Associated with Excessive Intake of Amino Acids. The Journal of Nutrition , 1633S-1639S.
4. Hulmi, J. J., Kovanen, V., Selanne, H. K., Hakkinen, K., & Mero, A. A. (2009). Acute and long-term effects of resistance exercise with or without protein ingestion on muscle hypertrophy and gene expression. Amino Acids , 297-308.
5. Lemon, P. W. (2000). Beyond the Zone: Protein Needs of Active Individuals. Journal of the American College of Nutrition , 513S-521S.
6. Lemon, P. W., Tarnopolsky, M. A., MacDougall, J. D., & Atkinson, S. A. (1992). Protein requirements and muscle mass/strength changes during intensitve training in navie bodybuilders. J Appl Physiol , 767-775.
7. Miyazaki, M., & Esser, K. A. (2009). Cellular mechanisms regulating protein synthesis and skeletal muscle hypertrophy in animals. J Appl Physiol , 1367-1373.
8. Tipton, K. D., Elliott, T. A., Cree, M. G., Aarsland, A. A., Sanfor, A. P., & Wolfe, R. R. (2007). Stimulation of net muscle protein synthesis by whey protein ingestion before and after exercise. Am J PHysiol Endocrinal Metab , E71-E76.
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