Originariamente Scritto da Luscio
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visto che vuoi cose scientifiche, per supportare quel che ho detto:
-questo è stato fatto su soggetti obesi, ma il risultato è cmq applicabile a soggetti normali (credo, visto che si parla di cambiamento della funzione renale...)
Changes in renal function during weight loss induced by high vs low-protein low-fat diets in overweight subjects
A Rosenvinge Skov1, S Toubro1, J Bülow2, K Krabbe3, H-H Parving4 and A Astrup1
1Research Department of Human Nutrition, The Royal Veterinary and Agricultural University, Copenhagen, Denmark
2Department of Clinical Physiology, Bispebjerg Hospital, Copenhagen, Denmark
3Danish Research Centre of Magnetic Resonance, Hvidovre University Hospital, Denmark
4Steno Diabetes Center, Gentofte, Denmark
Correspondence to: Arne Astrup, Research Department of Human Nutrition, The Royal Veterinary and Agricultural University, Rolighedsvej 30, 1958 Frederiksberg C, Copenhagen, Denmark.ast@kvl.dk
Abstract
BACKGROUND: Due to the high satiating effect of protein, a high-protein diet may be desirable in the treatment of obesity. However the long-term effect of different levels of protein intake on renal function is unclear.
OBJECTIVE: To assess the renal effects of high vs low protein contents in fat-reduced diets.
DESIGN: Randomized 6 months dietary intervention study comparing two controlled ad libitum diets with 30 energy (E%) fat content: high-protein (HP; 25 E%) or low-protein, (LP, 12 E% protein). All food was provided by self-selection in a shop at the department, and high compliance to the diet composition was confirmed by measurements of urinary nitrogen excretion.
SUBJECTS: 65 healthy, overweight and obese (25<body mass index (BMI)<34 kgm2).
RESULTS: Dietary protein intake changed from 91.1 gd to a 6 months intervention average of 70.4 gd (P<0.05) in the LP group and from 91.4 gd to 107.8 gd (P<0.05) in the HP group, producing changes in glomular filtration rate (GFR) of -7.1 mlmin in the LP group and +5.2 mlmin in the HP group (group effect: P<0.05). Kidney volume decreased by -6.2 cm3 in the LP group and increased by +9.1 cm3 in the HP group (P<0.05), whereas albuminuria remained unchanged in all groups.
CONCLUSION: Moderate changes in dietary protein intake cause adaptive alterations in renal size and function without indications of adverse effects.
-questo forse è + convincente...
Dietary protein intake and renal function.Martin WF, Armstrong LE, Rodriguez NR.
Department of Nutritional Sciences, University of Connecticut, Storrs, CT, USA. William.martin@uconn.edu
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.
Originariamente Scritto da andreas munzer
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Originariamente Scritto da Infausto_ManMade
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Fai lavorare inutilmente i reni... E non è poco 
Originariamente Scritto da Luscio
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Effect of a high-protein, energy-restricted diet on body composition, glycemic control, and lipid concentrations in overweight and obese hyperinsulinemic men and women1,2,3
Emma Farnsworth, Natalie D Luscombe, Manny Noakes, Gary Wittert, Eleni Argyiou and Peter M Clifton
1 From the Departments of Physiology (EF and NDL) and Medicine (GW), University of Adelaide, Australia; the CSIRO Health Sciences and Nutrition, Adelaide, Australia (MN and PMC); and the Centre for Human Nutrition, University of Sheffield, United Kingdom (EA).
Background: It is not clear whether varying the protein-to-carbohydrate ratio of weight-loss diets benefits body composition or metabolism.
Objective: The objective was to compare the effects of 2 weight-loss diets differing in protein-to-carbohydrate ratio on body composition, glucose and lipid metabolism, and markers of bone turnover.
Design: A parallel design included either a high-protein diet of meat, poultry, and dairy foods (HP diet: 27% of energy as protein, 44% as carbohydrate, and 29% as fat) or a standard-protein diet low in those foods (SP diet: 16% of energy as protein, 57% as carbohydrate, and 27% as fat) during 12 wk of energy restriction (6–6.3 MJ/d) and 4 wk of energy balance (8.2 MJ/d). Fifty-seven overweight volunteers with fasting insulin concentrations > 12 mU/L completed the study.
Results: Weight loss (7.9 ± 0.5 kg) and total fat loss (6.9 ± 0.4 kg) did not differ between diet groups. In women, total lean mass was significantly (P = 0.02) better preserved with the HP diet (-0.1 ± 0.3 kg) than with the SP diet (-1.5 ± 0.3 kg). Those fed the HP diet had significantly (P < 0.03) less glycemic response at weeks 0 and 16 than did those fed the SP diet. After weight loss, the glycemic response decreased significantly (P < 0.05) more in the HP diet group. The reduction in serum triacylglycerol concentrations was significantly (P < 0.05) greater in the HP diet group (23%) than in the SP diet group (10%). Markers of bone turnover, calcium excretion, and systolic blood pressure were unchanged.
Conclusion: Replacing carbohydrate with protein from meat, poultry, and dairy foods has beneficial metabolic effects and no adverse effects on markers of bone turnover or calcium excretion.
Effect of high protein vs high carbohydrate intake on insulin sensitivity, body weight, hemoglobin A1c, and blood pressure in patients with type 2 diabetes mellitus.
Sargrad KR, Homko C, Mozzoli M, Boden G.
Nutrition Center, Department of Bioscience and Biotechnology, Drexel University, Philadelphia, PA 19104, USA. ksargrad@drexel.edu
BACKGROUND: Extremely low carbohydrate/high protein diets are popular methods of weight loss. Compliance with these diets is poor and long-term effectiveness and the safety of these diets for patients with type 2 diabetes is not known. OBJECTIVE: The objective of the current study was to evaluate effects of less extreme changes in carbohydrate or protein diets on weight, insulin sensitivity, glycemic control, cardiovascular risk factors (blood pressure, lipid levels), and renal function in obese inner-city patients with type 2 diabetes. DESIGN: Study patients were admitted to the General Clinical Research Center for 24 hours for initial tests including a hyperinsulinemic-euglycemic clamp (for measurement of insulin sensitivity), bioelectrical impedance analysis (BIA) and anthropometric measurements (for assessment of body composition), indirect calorimetry (for measurement of REE), electronic blood pressure monitoring, and blood chemistries to measure blood lipids levels along with renal and hepatic functions. Six patients with type 2 diabetes (five women and one man) were randomly assigned to the high-protein diet (40% carbohydrate, 30% protein, 30% fat) and six patients (four women and two men) to the high-carbohydrate diet (55% carbohydrate, 15% protein, 30% fat). All patients returned to the General Clinical Research Center weekly for monitoring of food records; dietary compliance; and measurements of body weight, blood pressure, and blood glucose. After 8 weeks on these diets, all patients were readmitted to the General Clinical Research Center for the same series of tests. INTERVENTION: Twelve study patients were taught to select either the high-protein or high-carbohydrate diet and were followed for 8 weeks. MAIN OUTCOME MEASURES: Insulin sensitivity, hemoglobin A1c, weight, and blood pressure were measured. STATISTICAL ANALYSES: Statistical significance was assessed using two-tailed Student's t tests and two-way repeated measures analysis of variance. RESULTS: Both the high-carbohydrate and high-protein groups lost weight (-2.2+/-0.9 kg, -2.5+/-1.6 kg, respectively, P <.05) and the difference between the groups was not significant (P =.9). In the high-carbohydrate group, hemoglobin A1c decreased (from 8.2% to 6.9%, P <.03), fasting plasma glucose decreased (from 8.8 to 7.2 mmol/L, P <.02), and insulin sensitivity increased (from 12.8 to 17.2 micromol/kg/min, P <.03). No significant changes in these parameters occurred in the high-protein group, instead systolic and diastolic blood pressures decreased (-10.5+/-2.3 mm Hg, P =.003 and -18+/-9.0 mm Hg, P <.05, respectively). After 2 months on these hypocaloric diets, each diet had either no or minimal effects on lipid levels (total cholesterol, low-density lipoprotein, high-density lipoprotein), renal (blood urea nitrogen, serum creatinine), or hepatic function (aspartate aminotransferase, alanine aminotransferase, bilirubin).
Health Problems of High Protein, High Fat, Low Carb Diets
From Cathy Wong,
Your Guide to Alternative Medicine.
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Side Effects of the Atkins Diet
Do the Atkins diet and other high protein, high fat and low carb diets have side effects? The Physicians Committee for Responsible Medicine (PCRM) wants to find out.
In the fall of 2002, the PCRM began an online registry for people who may have suffered health complications related to high protein, low carb diets. Their website is www.atkinsdietalert.org. The registry specifically inquired about the following problems: heart attack, other heart problems, high cholesterol, diabetes, gout, gallbladder, colorectal cancer, other cancers, osteoporosis, reduced kidney function, kidney stones, constipation, difficulty concentrating, bad breath, and loss of energy.
After approximately one year until November 2003, approximately 188 individuals reported experiencing problems.
· 44% reported constipation
· 42% reported loss of energy
· 40% reported bad breath
· 31% reported difficulty concentrating
· 22% reported kidney problems: kidney stones (11%), severe kidney infections (2%), or reduced kidney function (9%)
· 5% reported gout
· 5% reported diabetes
· 5% reported osteoporosis
· 4% reported colorectal (1%) and other cancers (3%)
In addition, other problems that were reported by at least three people:
· 11 reported irritable bowel syndrome, severe abdominal pain, or cramps (6%)
· 9 reported pain, cramps, tingling or numbness in the limbs(5%)
· 9 reported feeling shaky and weak (5%)
· 9 reported vertigo, dizziness or lightheadedness(5%)
· 7 reported severe diarrhea (4%)
· 7 reported severe or repeated headaches (4%)
· 5 reported severe mood swings, apathy or depression (3%)
· 5 reported general malaise (3%)
· 4 reported nausea (2%)
· 4 reported severe menstrual problems (2%)
3 reported heart palpitations (2%)
The National Institutes of Health is funding a five year study of low- and high-carbohydrate diets to more fully assess the benefits and risks of these diets on bone mass, kidney function, blood vessel health and exercise tolerance.
The study will be conducted by a multicenter research team at Washington University, the University of Pennsylvania School of Medicine and the University of Colorado Health Sciences Center. It will also look at whether behavior intervention and modification might help people stick to these diets.
The research team conducted a trial that was published in the New England Journal of Medicine. They found that at three and six months, the Atkins dieters lost twice as much weight during the first six months than a low-fat, high-carbohydrate diet. However, dieters on both diets regained the weight and at one year, there was no statistical difference between the groups.
One result of the study that was somewhat surprising was that people on the Atkins diet had greater improvements in blood lipids than those on the low-fat, high carbohydrate diet.
In the Atkins group, there was a greater increase in high-density lipoprotein (HDL), or "good" cholesterol, and their serum triglycerides decreased more than the other group. Low HDL and high triglyceride levels increase risk of cardiovascular disease.
Dietary protein: an essential nutrient for bone health.Bonjour JP.
Service of Bone Diseases, University Hospital, Rue Micheli-Du-Crest, 1211 Geneva, Switzerland. Jean-Philippe.Bonjour@medecine.unige.ch.
Nutrition plays a major role in the development and maintenance of bone structures resistant to usual mechanical loadings. In addition to calcium in the presence of an adequate vitamin D supply, proteins represent a key nutrient for bone health, and thereby in the prevention of osteoporosis. In sharp opposition to experimental and clinical evidence, it has been alleged that proteins, particularly those from animal sources, might be deleterious for bone health by inducing chronic metabolic acidosis which in turn would be responsible for increased calciuria and accelerated mineral dissolution. This claim is based on an hypothesis that artificially assembles various notions, including in vitro observations on the physical-chemical property of apatite crystal, short term human studies on the calciuric response to increased protein intakes, as well as retrospective inter-ethnic comparisons on the prevalence of hip fractures. The main purpose of this review is to analyze the evidence that refutes a relation of causality between the elements of this putative patho-physiological "cascade" that purports that animal proteins are causally associated with an increased incidence of osteoporotic fractures. In contrast, many experimental and clinical published data concur to indicate that low protein intake negatively affects bone health. Thus, selective deficiency in dietary proteins causes marked deterioration in bone mass, micro architecture and strength, the hallmark of osteoporosis. In the elderly, low protein intakes are often observed in patients with hip fracture. In these patients intervention study after orthopedic management demonstrates that protein supplementation as given in the form of casein, attenuates post-fracture bone loss, increases muscles strength, reduces medical complications and hospital stay. In agreement with both experimental and clinical intervention studies, large prospective epidemiologic observations indicate that relatively high protein intakes, including those from animal sources are associated with increased bone mineral mass and reduced incidence of osteoporotic fractures. As to the increased calciuria that can be observed in response to an augmentation in either animal or vegetal proteins it can be explained by a stimulation of the intestinal calcium absorption. Dietary proteins also enhance IGF-1, a factor that exerts positive activity on skeletal development and bone formation. Consequently, dietary proteins are as essential as calcium and vitamin D for bone health and osteoporosis prevention. Furthermore, there is no consistent evidence for superiority of vegetal over animal proteins on calcium metabolism, bone loss prevention and risk reduction of fragility fractures.
Dietary protein and bone health.Ginty F.
MRC Human Nutrition Research, The Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK. Fiona.Ginty@mrc-hnr.cam.ac.uk
The effects of dietary protein on bone health are paradoxical and need to be considered in context of the age, health status and usual diet of the population. Over the last 80 years numerous studies have demonstrated that a high protein intake increases urinary Ca excretion and that on average 1 mg Ca is lost in urine for every 1 g rise in dietary protein. This relationship is primarily attributable to metabolism of S amino acids present in animal and some vegetable proteins, resulting in a greater acid load and buffering response by the skeleton. However, many of these early studies that demonstrated the calciuric effects of protein were limited by low subject numbers, methodological errors and the use of high doses of purified forms of protein. Furthermore, the cross-cultural and population studies that showed a positive association between animal-protein intake and hip fracture risk did not consider other lifestyle or dietary factors that may protect or increase the risk of fracture. The effects of protein on bone appear to be biphasic and may also depend on intake of Ca- and alkali-rich foods, such as fruit and vegetables. At low protein intakes insulin-like growth factor production is reduced, which in turn has a negative effect on Ca and phosphate metabolism, bone formation and muscle cell synthesis. Although growth and skeletal development is impaired at very low protein intakes, it is not known whether variations in protein quality affect the achievement of optimal peak bone mass in adolescents and young adults. Prospective studies in the elderly in the USA have shown that the greatest bone losses occur in elderly men and women with an average protein intake of 16-50 g/d. Although a low protein intake may be indicative of a generally poorer diet and state of health, there is a need to evaluate whether there is a lower threshold for protein intake in the elderly in Europe that may result in increased bone loss and risk of osteoporotic fracture.
? beh io ci credo.....peccato che i carbo siano cosi' buoni
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