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צדקת חחחח
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.
Abstract
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
PMID: 10722779 [PubMed - indexed for MEDLINE]
Optimal intakes of protein in the human diet
* Article author query
* millward dj [PubMed] [Google Scholar]
D. Joe Millwarda1 c1
a1 Centre for Nutrition and Food Safety, School of Biological Sciences, University of Surrey, Guildford GU2 5XH, UK
Abstract
For protein, progress is slow in defining quantifiable indicators of adequacy other than balance and growth. As far as current requirements are concerned, only in the case of infants and children is there any case for revision, and this change is to lower values. Such intakes would appear to be safe when consumed as milk formula. In pregnancy, notwithstanding the concern that deficiency may influence programming of disease in later life, there is little evidence of any increased need, and some evidence that increased intakes would pose a risk. For the elderly there is no evidence of an increased requirement or of benefit from increased intakes, except possibly for bone health. For adults, while we now know much more about metabolic adaptation to varying intakes, there would appear to be no case for a change in current recommendations. As far as risks and benefits of high intakes are concerned, there is now only a weak case for risk for renal function. For bone health the established views of risk of high protein intakes are not supported by newly emerging data, with benefit indicated in the elderly. There is also circumstantial evidence for benefit on blood pressure and stroke mortality. With athletes there is little evidence of benefit of increased intakes in terms of performance, with older literature suggesting an adverse influence. Thus, given that a safe upper limit is currently defined as twice the reference nutrient intake, and that for individuals with high energy requirements this value (1.5 g/kg per d) is easily exceeded, there is a case for revising the definition of a safe upper limit.
Dietary protein intake and renal function
William F Martin1* email, Lawrence E Armstrong2* email and Nancy R Rodriguez1* email
1 Department of Nutritional Sciences, University of Connecticut, Storrs, CT, USA
2 Department of Kinesiology, University of Connecticut, Storrs, CT, USA
author email corresponding author email* Contributed equally
Nutrition & Metabolism 2005, 2:25doi:10.1186/1743-7075-2-25
The electronic version of this article is the complete one and can be found online at: http://www.nutritionandmetabolism.com/content/2/1/25
Received: 8 March 2005
Accepted: 20 September 2005
Published: 20 September 2005
© 2005 Martin et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Recent trends in weight loss diets have led to a substantial increase in protein intake by individuals. As a result, the safety of habitually consuming dietary protein in excess of recommended intakes has been questioned. In particular, there is concern that high protein intake may promote renal damage by chronically increasing glomerular pressure and hyperfiltration. There is, however, a serious question as to whether there is significant evidence to support this relationship in healthy individuals. In fact, some studies suggest that hyperfiltration, the purported mechanism for renal damage, is a normal adaptative mechanism that occurs in response to several physiological conditions. This paper reviews the available evidence that increased dietary protein intake is a health concern in terms of the potential to initiate or promote renal disease. While protein restriction may be appropriate for treatment of existing kidney disease, we find no significant evidence for a detrimental effect of high protein intakes on kidney function in healthy persons after centuries of a high protein Western diet.
Int J Sport Nutr Exerc Metab. 2006 Apr;16(2):129-52.
A review of issues of dietary protein intake in humans.
Bilsborough S, Mann N.
B Personal Pty Ltd., Melbourne, Victoria 3001, Australia.
Abstract
Considerable debate has taken place over the safety and validity of increased protein intakes for both weight control and muscle synthesis. The advice to consume diets high in protein by some health professionals, media and popular diet books is given despite a lack of scientific data on the safety of increasing protein consumption. The key issues are the rate at which the gastrointestinal tract can absorb amino acids from dietary proteins (1.3 to 10 g/h) and the liver's capacity to deaminate proteins and produce urea for excretion of excess nitrogen. The accepted level of protein requirement of 0.8g x kg(-1) x d(-1) is based on structural requirements and ignores the use of protein for energy metabolism. High protein diets on the other hand advocate excessive levels of protein intake on the order of 200 to 400 g/d, which can equate to levels of approximately 5 g x kg(-1) x d(-1), which may exceed the liver's capacity to convert excess nitrogen to urea. Dangers of excessive protein, defined as when protein constitutes > 35% of total energy intake, include hyperaminoacidemia, hyperammonemia, hyperinsulinemia nausea, diarrhea, and even death (the "rabbit starvation syndrome"). The three different measures of defining protein intake, which should be viewed together are: absolute intake (g/d), intake related to body weight (g x kg(-1) x d(-1)) and intake as a fraction of total energy (percent energy). A suggested maximum protein intake based on bodily needs, weight control evidence, and avoiding protein toxicity would be approximately of 25% of energy requirements at approximately 2 to 2.5 g x kg(-1) x d(-1), corresponding to 176 g protein per day for an 80 kg individual on a 12,000kJ/d diet. This is well below the theoretical maximum safe intake range for an 80 kg person (285 to 365 g/d).
PMID: 16779921 [PubMed - indexed for MEDLINE]
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