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References for protein intakes and bodybuilding risks

Sports Med. 2004; 34(5): 317-27.
Macronutrient considerations for the sport of bodybuilding.
Lambert CP, Frank LL, Evans WJ.
Nutrition, Metabolism, and Exercise Laboratory, Donald W. Reynolds Center on Aging, Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
Participants in the sport of bodybuilding are judged by appearance rather than performance. In this respect, increased muscle size and definition are critical elements of success. The purpose of this review is to evaluate the literature and provide recommendations regarding macronutrient intake during both 'off-season' and 'pre-contest' phases. bodybuilders attempt to increase muscle mass during the off-season (no competitive events), which may be the great majority of the year. During the off-season, it is advantageous for the bodybuilder to be in positive energy balance so that extra energy is available for muscle anabolism. Additionally, during the off-season, adequate protein must be available to provide amino acids for protein synthesis. For 6-12 weeks prior to competition, bodybuilders attempt to retain muscle mass and reduce body fat to very low levels. During the pre-contest phase, the bodybuilder should be in negative energy balance so that body fat can be oxidised. Furthermore, during the pre-contest phase, protein intake must be adequate to maintain muscle mass. There is evidence that a relatively high protein intake (approximately 30% of energy intake) will reduce lean mass loss relative to a lower protein intake (approximately 15% of energy intake) during energy restriction. The higher protein intake will also provide a relatively large thermic effect that may aid in reducing body fat. In both the off-season and pre-contest phases, adequate dietary carbohydrate should be ingested (55-60% of total energy intake) so that training intensity can be maintained. Excess dietary saturated fat can exacerbate coronary artery disease; however, low-fat diets result in a reduction in circulating testosterone. Thus, we suggest dietary fats comprise 15-20% of the bodybuilders' off-season and pre-contest diets. Consumption of protein/amino acids and carbohydrate immediately before and after training sessions may augment protein synthesis, muscle glycogen resynthesis and reduce protein degradation. The optimal rate of carbohydrate ingested immediately after a training session should be 1.2 g/kg/hour at 30-minute intervals for 4 hours and the carbohydrate should be of high glycaemic index. In summary, the composition of diets for bodybuilders should be 55-60% carbohydrate, 25-30% protein and 15-20% of fat, for both the off-season and pre-contest phases. During the off-season the diet should be slightly hyperenergetic (approximately 15% increase in energy intake) and during the pre-contest phase the diet should be hypoenergetic (approximately 15% decrease in energy intake).

Int J Sport Nutr Exerc Metab. 2000 Mar;10(1):28-38.
Do regular high protein diets have potential health risks on kidney function in athletes?
Poortmans JR, Dellalieux O.
Department of Physiological Chemistry, Institute of Physical Education and Kinesiotherapy, Free University of Brussels, Belgium.
Excess protein and amino acid intake have been recognized as hazardous potential implications for kidney function, leading to progressive impairment of this organ. It has been suggested in the literature, without clear evidence, that high protein intake by athletes has no harmful consequences on renal function. This study investigated body-builders (BB) and other well-trained athletes (OA) with high and medium protein intake, respectively, in order to shed light on this issue. The athletes underwent a 7-day nutrition record analysis as well as blood sample and urine collection to determine the potential renal consequences of a high protein intake. The data revealed that despite higher plasma concentration of uric acid and calcium, Group BB had renal clearances of creatinine, urea, and albumin that were within the normal range. The nitrogen balance for both groups became positive when daily protein intake exceeded 1.26 g.kg but there were no correlations between protein intake and creatinine clearance, albumin excretion rate, and calcium excretion rate. To conclude, it appears that protein intake under 2. 8 g.kg does not impair renal function in well-trained athletes as indicated by the measures of renal function used in this study

Eur J Clin Nutr. 1996 Nov;50(11):734-40.
Effect of chronic dietary protein intake on the renal function in healthy subjects.
Brändle E, Sieberth HG, Hautmann RE.
Department of Urology, University of Ulm, Germany.
OBJECTIVE: Relatively little is known about the influence of chronic oral protein intake on the kidney function. In most studies only the effect of a short-term change in protein intake [6-28 days] or the effect of an acute protein load on the glomerular filtration rate was studied. The purpose of this study was to investigate the effect of chronic oral protein intake on endogenous creatinine clearance and on the albumin excretion rate.
DESIGN AND SUBJECTS: In a prospective study 88 healthy volunteers with normal renal function (32 vegetarians, 12 body-builders with no supplementary protein concentrates, 28 body-builders with supplementary protein concentrates and 16 subjects with no special diet) were examined. In order to investigate the effect of chronic oral protein intake, the participants were on their diet for at least 4 months.
RESULTS: Endogenous creatinine clearance as a measure for glomerular filtration rate varied between 32 ml/min and 197 ml/min or 34 and 186 ml/min x 1.73 m2, respectively. Nitrogen excretion rate was used as a measure for the daily protein intake, since it is known to correlate linearly with the daily protein intake. Nitrogen excretion rates ranged between 2.66 g/d and 33.93 g/d reflecting a daily protein consumption between 17 and 212 g/d or 0.29 g/kg bw/d and 2.6 g/kg bw/day, respectively. Between nitrogen excretion rate and endogenous creatinine clearance a non linear, highly significant correlation was found showing a saturation with a maximum endogenous creatinine clearance of 181.7 ml/min (dose response curve). A similar correlation was observed between urea excretion rate and endogenous creatinine clearance. Using a model for multiple regression analysis the dependence of the albumin excretion rate on nitrogen excretion rate and endogenous creatinine clearance was examined. Only a significant correlation was found between albumin excretion rate and endogenous creatinine clearance, while the correlation between albumin excretion rate and nitrogen excretion rate was not significant.
CONCLUSION: This investigation shows that chronic oral protein intake of widely varying amounts of protein is a crucial control variable for the glomerular filtration rate in subjects with healthy kidneys. It is suggested that these changes reflect in part structural changes of the glomerulus and tubules due to chronic protein intake.

S Afr Med J. 1987 Dec 19;72(12):831-4.
Nutrient intake and dietary supplementation in body-builders.
Faber M, Benadé AJ.
National Research Institute for Nutritional Diseases, South African Medical Research Council, Parowvallei, CP.
The micronutrient intake of a group of 76 body-builders was studied. Sixty-three per cent of the subjects supplemented their diets with vitamin and mineral pills. The highest pill consumption was 87 pills per day. Fifty-nine per cent of the subjects used high-protein powders. The benefits of these powders is open to question, since the diet already supplied a high 2.2 g protein per kilogram of body weight. Thirty-nine per cent of the subjects used vitamin/mineral pills as well as protein powders. Because of the use of dietary supplements, the food in the diet supplied only a small fraction of the total intake of most of the micronutrients. The food supplied adequate amounts of nutrients according to the US Recommended Dietary Allowances, and the use of dietary supplements can therefore not be justified.

Int J Sports Med. 1986 Dec;7(6):342-6.
Dietary intake, anthropometric measurements, and blood lipid values in weight training athletes (bodybuilders).
Faber M, Benadé AJ, van Eck M.
Abstract
Dietary intake, plasma lipid levels, and anthropometric measurements were studied in 76 weight trained athletes (bodybuilders) who had been following a consistent eating and training program for at least 2 years prior to the study. Dietary data were collected using the 7-day diet record. Nutrient analysis indicated that these athletes followed an atherogenic diet, characterized by a high-fat, high-cholesterol intake. The high-cholesterol intake was due to a high egg intake, which varied from 0 to 81 eggs per week. Although those athletes with a high egg intake consumed significantly more fat and cholesterol than those with a low egg intake, plasma total cholesterol levels (mean = 182.9 +/- 25.7) did not differ over the range of egg intakes. Plasma HDL-cholesterol levels were higher and plasma triacylglycerol levels were lower at a high egg intake compared with that at a low egg intake. Plasma uric acid was not affected by the high animal protein intake. Despite the unfavorable intake of macronutrients, food alone supplied adequate amounts of micronutrients as compared with the RDA. Using different measurements of obesity, it was difficult to classify this group of athletes as overweight or obese, due to increased muscle development.

Phys Sportsmed. 2009 Jun;37(2):13-21.
Protein for exercise and recovery.
Kreider RB, Campbell B.
Exercise and Sport Nutrition Lab, Department of Health and Kinesiology, 158H Read Building, 4243 TAMU, Texas A&M University, College Station, TX 78743-4243, USA.
Dietary protein is required to promote growth, repair damaged cells and tissue, synthesize hormones, and for a variety of metabolic activities. There are multiple sources of proteins available; however, animal sources of protein contain all essential amino acids and are considered complete sources of protein, whereas plant proteins lack some of the essential amino acids and are therefore classified as incomplete. There is a significant body of evidence to indicate that individuals who are engaged in intense training require more dietary protein than sedentary counterparts (ie, 1.4-2 g/kg/day). For most individuals, this level of protein intake can be obtained from a regular and varied diet. However, recent evidence indicates that ingesting protein and/or amino acids prior to, during, and/or following exercise can enhance recovery, immune function, and growth and maintenance of lean body mass. Consequently, protein and amino acid supplements can serve as a convenient way to ensure a timely and/or adequate intake for athletes. Finally, adequate intake and appropriate timing of protein ingestion has been shown to be beneficial in multiple exercise modes, including endurance, anaerobic, and strength exercise.

Crit Rev Food Sci Nutr. 1999 Jul;39(4):317-28.
Nutritional supplements to increase muscle mass.
Clarkson PM, Rawson ES.
Department Exercise Science, University of Massachusetts, Amherst 01003, USA.
Although nutritional supplements purported to increase muscle mass are widely available at health food stores, gyms, by mail order, and over the Internet, many of these supplements have little or no data to support their claims. This article reviews the theory and research behind popular nutritional supplements commonly marketed as muscle mass builders. Included are the minerals chromium, vanadyl sulfate, and boron, the steroid hormone dehydroepiandrosterone (DHEA), beta-methyl-hydroxy-beta-methylbutyrate (HMB), creatine, protein supplements, and amino acids. Research has shown that chromium vanadyl sulfate, and boron do not appear to be effective in increasing lean body mass. The few studies examining DHEA have not supported the claim of increased muscle gain. Preliminary work on HMB supports an anticatabolic effect, but only one human study is currently available. Many studies reported increased body mass and several have reported increased lean body mass following creatine ingestion. This weight gain is most likely water retention in muscle but could also be due to some new muscle protein. Although athletes have a greater protein requirement than sedentary individuals, this is easily obtained through the diet, negating the use of protein supplements. Studies on amino acids have not supported their claim to increase growth hormone or insulin secretion. Nutritional supplements can be marketed without FDA approval of safety or effectiveness. Athletes who choose to ingest these supplements should be concerned with unsubstantiated claims, questionable quality control, and safety of long-term use.

Int J Eat Disord. 1995 Jul;18(1):49-57.
Weight loss, psychological, and nutritional patterns in competitive male bodybuilders.
Andersen RE, Barlett SJ, Morgan GD, Brownell KD.
Department of Psychiatry, School of Medicine, University of Pennsylvania, USA.
There has been increasing interest in the effects of chronic dieting and of repeated cycles of weight loss and regain in athletes. The purpose of this investigation was to examine the eating and weight loss practices, nutrition, and psychological factors in 45 male bodybuilders competing in a drug-free competition. Subjects completed a questionnaire on the morning of a Bodybuilding competition to assess the weight loss and dietary history, psychological distress, reports of binge eating, and vitamin and mineral supplement usage. The subjects reported high levels of dieting, weight loss, and weight regain. The mean weight loss reported in the competitive season was 6.8 kg; the mean weight gain reported was 6.2 kg. Eighty-five percent reported gaining weight while 46% reported episodes of binge eating after competitions. Most (81.5%) reported being preoccupied with food sometimes, often, or always. Between 30 and 50% reported psychological distress when preparing for competition (anxiety, short temper, anger). A similar number (30-50%) reported using amino acid, protein, and vitamin supplements. It appears that severe dieting practices are common in the sport of competitive Bodybuilding. The potential physiological, psychological, and health implications of these practices, combined with the growing popularity of Bodybuilding, are of sufficient importance to warrant further attention by investigators and the Bodybuilding community.

Schweiz Med Wochenschr. 1991 Aug 17;121(33):1163-5.
[Bodybuilding: hypokalemia and hypophosphatemia].
[Article in German]
Britschgi F, Zünd G.
Medizinische Abteilung des Kantonsspitals Obwalden, Sarnen.
In preparing for competitive bodybuilding, bodybuilders--in addition to continuous and hard muscle training--engage in stringent dietetic manipulations: the first few months of hypercaloric nutrition, rich in proteins, are devoted to the build-up of muscle mass. A second phase of reduced caloric intake is designed reduce subcutaneous fat, while, during the last week of preparations, extreme carbohydrate intake aims at loading muscles with glycogen. Simultaneously, sodium and water restriction results in extracellular and therefore subcutaneous volume deficit and better "definition" of muscle contours and structure. In the course of these dietetic manipulations a young body builder develops hypokalemia, hypophosphatemia, rhabdomyolysis and flaccid tetraparesis. The disturbances are pathophysiologically predictable.

Sports Med. 1999 Feb;27(2):97-110.
Dietary supplements and the promotion of muscle growth with resistance exercise.
Kreider RB.
Department of Human Movement Sciences and Education, University of Memphis, Tennessee, USA
Abstract
Nutritional strategies of overfeeding, ingesting carbohydrate/protein before and after exercise, and dietary supplementation of various nutrients [e.g. protein, glutamine, branched-chain amino acid, creatine, leucine, beta-hydroxy beta-methyl-butyrate (beta-HMB), chromium, vanadyl sulfate, boron, prasterone (dehydroepiandrosterone [DHEA]) and androstenedione] have been purported to promote gains in fat-free mass during resistance training. Most studies indicate that chromium, vanadyl sulfate and boron supplementation do not affect muscle growth. However, there is evidence that ingesting carbohydrate/protein prior to exercise may reduce catabolism during exercise and that ingesting carbohydrate/protein following resistance-exercise may promote a more anabolic hormonal profile. Furthermore, glutamine, creatine, leucine, and calcium beta-HMB may affect protein synthesis. Creatine and calcium beta-HMB supplementation during resistance training have been reported to increase fat-free mass in athletic and nonathletic populations. Prasterone supplementation has been reported to increase testosterone and fat-free mass in nontrained populations. However, results are equivocal, studies have yet to be conducted on athletes, and prasterone is considered a banned substance by some athletic organisations. This paper discusses rationale and effectiveness of these nutritional strategies in promoting lean tissue accretion during resistance training.

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