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BMC Endocrine Disorders Aug 2021Several studies have investigated the association between dietary protein and the risk of diabetic nephropathy (DN); however, there is no agreement on the type of...
BACKGROUND
Several studies have investigated the association between dietary protein and the risk of diabetic nephropathy (DN); however, there is no agreement on the type of dietary protein sources that might increase the risk of DN. This study was conducted to investigate the associations between different protein sources and the odds of DN developing in Iranian women with existing type 2 diabetes.
METHODS
In this case-control study, 105 women with DN and 105 controls, matched for age and diabetes duration, were selected from the Kowsar Diabetes Clinic in Semnan, Iran. Dietary intake was assessed using a validated and reliable food frequency questionnaire. Dietary protein patterns were estimated using the factor analysis method. Multivariate logistic regression was performed to examine the association between protein patterns and the odds of developing DN.
RESULTS
Two patterns were identified: the Mediterranean-based Dietary Protein Sources (MDPS) pattern which is rich in low-fat dairy, fish, poultry, soy, and legumes, and the Western-based Dietary Protein Sources (WDPS) pattern, rich in red and processed meats, eggs, and high-fat dairy. After adjusting for several confounders, greater adherence (third vs. the first tertile) to the MDPS pattern was associated with lower odds of DN (OR = 0.03; 95 % CI: 0.00, 0.10). In contrast, a strong positive association was observed between adherence to the WDPS pattern and DN (OR = 2.81; 95 % CI: 1.09-7.21).
CONCLUSIONS
Our results show that there is a potential association between the type of protein sources consumed and the odds of DN development in women with type 2 diabetes. Further studies are needed to confirm these findings.
Topics: Adult; Aged; Biomarkers; Case-Control Studies; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Dietary Proteins; Female; Follow-Up Studies; Humans; Iran; Male; Middle Aged; Prognosis; Risk Factors
PubMed: 34452618
DOI: 10.1186/s12902-021-00841-3 -
Current Opinion in Lipidology Feb 2011Both dietary calcium and vitamin D are undoubtedly beneficial to skeletal health. In contrast, despite intense investigation, the impact of dietary protein on calcium... (Review)
Review
PURPOSE OF REVIEW
Both dietary calcium and vitamin D are undoubtedly beneficial to skeletal health. In contrast, despite intense investigation, the impact of dietary protein on calcium metabolism and bone balance remains controversial. A widely held view is that high intakes of animal protein result in increased bone resorption, reduced bone mineral density, and increased fractures because of its ability to generate a high fixed metabolic acid load. The purpose of this review is to present the recent or most important epidemiological and clinical trials in humans that evaluated dietary protein's impact on skeletal health.
RECENT FINDINGS
Many epidemiological studies have found a significant positive relationship between protein intake and bone mass or density. Similarly, isotopic studies in humans have also demonstrated greater calcium retention and absorption by individuals consuming high-protein diets, particularly when the calcium content of the diet was limiting. High-protein intake may positively impact bone health by several mechanisms, including calcium absorption, stimulation of the secretion of insulin-like growth factor-1, and enhancement of lean body mass. The concept that an increase in dietary protein induces a large enough shift in systemic pH to increase osteoclastic bone resorption seems untenable.
SUMMARY
Recent epidemiological, isotopic and meta-analysis studies suggest that dietary protein works synergistically with calcium to improve calcium retention and bone metabolism. The recommendation to intentionally restrict dietary protein to improve bone health is unwarranted, and potentially even dangerous to those individuals who consume inadequate protein.
Topics: Bone and Bones; Calcium; Dietary Proteins; Humans
PubMed: 21102327
DOI: 10.1097/MOL.0b013e3283419441 -
The American Journal of Clinical... Dec 2009There has been a resurgence of interest in the controversial relation between dietary protein and bone health. (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
There has been a resurgence of interest in the controversial relation between dietary protein and bone health.
OBJECTIVE
This article reports on the first systematic review and meta-analysis of the relation between protein and bone health in healthy human adults.
DESIGN
The MEDLINE (January 1966 to September 2007) and EMBASE (1974 to July 2008) databases were electronically searched for all relevant studies of healthy adults; studies of calcium excretion or calcium balance were excluded.
RESULTS
In cross-sectional surveys, all pooled r values for the relation between protein intake and bone mineral density (BMD) or bone mineral content at the main clinically relevant sites were significant and positive; protein intake explained 1-2% of BMD. A meta-analysis of randomized placebo-controlled trials indicated a significant positive influence of all protein supplementation on lumbar spine BMD but showed no association with relative risk of hip fractures. No significant effects were identified for soy protein or milk basic protein on lumbar spine BMD.
CONCLUSIONS
A small positive effect of protein supplementation on lumbar spine BMD in randomized placebo-controlled trials supports the positive association between protein intake and bone health found in cross-sectional surveys. However, these results were not supported by cohort study findings for hip fracture risk. Any effects found were small and had 95% CIs that were close to zero. Therefore, there is a small benefit of protein on bone health, but the benefit may not necessarily translate into reduced fracture risk in the long term.
Topics: Bone Density; Cross-Sectional Studies; Dietary Proteins; Fractures, Bone; Humans; Risk
PubMed: 19889822
DOI: 10.3945/ajcn.2009.27799 -
Experimental Biology and Medicine... Mar 2018Maternal nutrition during gestation, especially dietary protein intake, is a key determinant in embryonic survival, growth, and development. Low maternal dietary protein... (Review)
Review
Maternal nutrition during gestation, especially dietary protein intake, is a key determinant in embryonic survival, growth, and development. Low maternal dietary protein intake can cause embryonic losses, intra-uterine growth restriction, and reduced postnatal growth due to a deficiency in specific amino acids that are important for cell metabolism and function. Of note, high maternal dietary protein intake can also result in intra-uterine growth restriction and embryonic death, due to amino acid excesses, as well as the toxicity of ammonia, homocysteine, and HS that are generated from amino acid catabolism. Maternal protein nutrition has a pronounced impact on fetal programming and alters the expression of genes in the fetal genome. As a precursor to the synthesis of molecules (e.g. nitric oxide, polyamines, and creatine) with cell signaling and metabolic functions, L-arginine (Arg) is essential during pregnancy for growth and development of the conceptus. With inadequate maternal dietary protein intake, Arg and other important amino acids are deficient in mother and fetus. Dietary supplementation of Arg during gestation has been effective in improving embryonic survival and development of the conceptus in many species, including humans, pigs, sheep, mice, and rats. Both the balance among amino acids and their quantity are critical for healthy pregnancies and offspring. Impact statement This review aims at: highlighting adverse effects of elevated levels of ammonia in mother or fetus on embryonic/fetal survival, growth, and development; helping nutritionists and practitioners to understand the mechanisms whereby elevated levels of ammonia in mother or fetus results in embryonic/fetal death, growth restriction, and developmental abnormalities; and bringing, into the attention of nutritionists and practitioners, the problems of excess or inadequate dietary intake of protein or amino acids on pregnancy outcomes in animals and humans. The article provides new, effective means to improve embryonic/fetal survival and growth in mammals.
Topics: Animals; Dietary Proteins; Dietary Supplements; Fetal Development; Humans; Survival
PubMed: 29466875
DOI: 10.1177/1535370218758275 -
Nutrients Nov 2016Protein is important to the human body, and different sources of protein may have different effects on the risk of breast cancer. Thus, we conducted a meta-analysis to... (Meta-Analysis)
Meta-Analysis Review
Protein is important to the human body, and different sources of protein may have different effects on the risk of breast cancer. Thus, we conducted a meta-analysis to investigate the association between different dietary protein sources and breast cancer risk. PubMed and several databases were searched until December 2015. Relevant articles were retrieved according to specific searching criteria. Forty-six prospective studies were included. The summary relative risk (RR) for highest versus lowest intake was 1.07 (95% confidence interval (CI) 1.01-1.14, ² = 34.6%) for processed meat, 0.92 (95% CI 0.84-1.00, ² = 0%) for soy food, 0.93 (95% CI 0.85-1.00, ² = 40.1%) for skim milk, and 0.90 (95% CI 0.82-1.00, ² = 0%) for yogurt. Similar conclusions were obtained in dose-response association for each serving increase: total red meat (RR: 1.07; 95% CI 1.01-1.14, ² = 7.1%), fresh red meat (RR: 1.13; 95% CI 1.01-1.26, ² = 56.4%), processed meat (RR: 1.09; 95% CI 1.02-1.17, ² = 11.8%), soy food (RR: 0.91; 95% CI 0.84-1.00, ² = 0%), and skim milk (RR: 0.96; 95% CI 0.92-1.00, ² = 11.9%). There was a null association between poultry, fish, egg, nuts, total milk, and whole milk intake and breast cancer risk. Higher total red meat, fresh red meat, and processed meat intake may be risk factors for breast cancer, whereas higher soy food and skim milk intake may reduce the risk of breast cancer.
Topics: Animals; Breast Neoplasms; Diet, Healthy; Dietary Proteins; Egg Proteins, Dietary; Female; Humans; Incidence; Meat Products; Milk Proteins; Odds Ratio; Plant Proteins, Dietary; Poultry; Prospective Studies; Protective Factors; Recommended Dietary Allowances; Red Meat; Risk Assessment; Risk Factors; Risk Reduction Behavior; Soybean Proteins
PubMed: 27869663
DOI: 10.3390/nu8110730 -
PloS One Aug 2010Elevated blood pressure (BP), which is a major risk factor for cardiovascular disease, is highly prevalent worldwide. Recently, interest has grown in the role of dietary... (Review)
Review
BACKGROUND
Elevated blood pressure (BP), which is a major risk factor for cardiovascular disease, is highly prevalent worldwide. Recently, interest has grown in the role of dietary protein in human BP. We performed a systematic review of all published scientific literature on dietary protein, including protein from various sources, in relation to human BP.
METHODOLOGY/PRINCIPAL FINDINGS
We performed a MEDLINE search and a manual search to identify English language studies on the association between protein and blood pressure, published before June 2010. A total of 46 papers met the inclusion criteria. Most observational studies showed no association or an inverse association between total dietary protein and BP or incident hypertension. Results of biomarker studies and randomized controlled trials indicated a beneficial effect of protein on BP. This beneficial effect may be mainly driven by plant protein, according to results in observational studies. Data on protein from specific sources (e.g. from fish, dairy, grain, soy, and nut) were scarce. There was some evidence that BP in people with elevated BP and/or older age could be more sensitive to dietary protein.
CONCLUSIONS/SIGNIFICANCE
In conclusion, evidence suggests a small beneficial effect of protein on BP, especially for plant protein. A blood pressure lowering effect of protein may have important public health implications. However, this warrants further investigation in randomized controlled trials. Furthermore, more data are needed on protein from specific sources in relation to BP, and on the protein-BP relation in population subgroups.
Topics: Animals; Biomarkers; Blood Pressure; Clinical Trials as Topic; Dietary Proteins; Humans; Plant Proteins; Species Specificity
PubMed: 20711407
DOI: 10.1371/journal.pone.0012102 -
Hormone Molecular Biology and Clinical... Oct 2016Dietary protein represents an important nutrient for bone health and thereby for the prevention of osteoporosis. Besides its role as a brick provider for building the... (Review)
Review
Dietary protein represents an important nutrient for bone health and thereby for the prevention of osteoporosis. Besides its role as a brick provider for building the organic matrix of skeletal tissues, dietary protein stimulates the production of the anabolic bone trophic factor IGF-I (insulin-like growth factor I). The liver is the main source of circulating IGF-I. During growth, protein undernutrition results in reduced bone mass and strength. Genetic defect impairing the production of IGF-I markedly reduces bone development in both length and width. The serum level of IGF-I markedly increases and then decreases during pubertal maturation in parallel with the change in bone growth and standing height velocity. The impact of physical activity on bone structure and strength is enhanced by increased dietary protein consumption. This synergism between these two important environmental factors can be observed in prepubertal boys, thus modifying the genetically determined bone growth trajectory. In anorexia nervosa, IGF-I is low as well as bone mineral mass. In selective protein undernutrition, there is a resistance to the exogenous bone anabolic effect of IGF-I. A series of animal experiments and human clinical trials underscore the positive effect of increased dietary intake of protein on calcium-phosphate economy and bone balance. On the contrary, the dietary protein-induced acidosis hypothesis of osteoporosis is not supported by several experimental and clinical studies. There is a direct effect of amino acids on the local production of IGF-I by osteoblastic cells. IGF-I is likely the main mediator of the positive effect of parathyroid hormone (PTH) on bone formation, thus explaining the reduction in fragility fractures as observed in PTH-treated postmenopausal women. In elderly women and men, relatively high protein intake protects against spinal and femoral bone loss. In hip fracture patients, isocaloric correction of the relatively low protein intake results in: increased IGF-I serum level, significant attenuation of postsurgical bone loss, improved muscle strength, better recovery, and shortened hospital stay. Thus, dietary protein contributes to bone health from early childhood to old age. An adequate intake of protein should be recommended in the prevention and treatment of osteoporosis.
Topics: Animals; Bone Density; Dietary Proteins; Female; Humans; Insulin-Like Growth Factor I; Male; Osteogenesis; Osteoporosis
PubMed: 26985688
DOI: 10.1515/hmbci-2016-0003 -
Physiology & Behavior Oct 2022Low-protein diets can impact food intake and appetite, but it is not known if motivation for food is changed. In the present study, we used an operant behavioral task -...
Low-protein diets can impact food intake and appetite, but it is not known if motivation for food is changed. In the present study, we used an operant behavioral task - the progressive ratio test - to assess whether motivation for different foods was affected when rats were maintained on a protein-restricted diet (REST, 5% protein diet) compared to non-restricted control rats (CON, 18% protein). Rats were tested either with nutritionally-balanced pellets (18.7% protein, Experiment 1) or protein-rich pellets (35% protein, Experiment 2) as reinforcers. Protein restriction increased breakpoint for protein-rich pellets, relative to CON rats, whereas no difference in breakpoint for nutritionally-balanced pellets was observed between groups. When given free access to either nutritionally-balanced pellets or protein-rich pellets, REST and CON rats did not differ in their intake. We also tested whether a previous history of protein restriction might affect present motivation for different types of food by assessing breakpoint of previously REST animals that were subsequently put on standard maintenance chow (protein-repleted rats, REPL, Experiment 2). REPL rats did not show increased breakpoint, relative to their initial encounter with protein-rich pellets while they were protein-restricted. This study demonstrates that restriction of dietary protein induces a selective increased motivation for protein-rich food, a behavior that disappears once rats are not in need of protein.
Topics: Animals; Appetite; Conditioning, Operant; Diet, Protein-Restricted; Dietary Proteins; Food Preferences; Motivation; Rats
PubMed: 35700813
DOI: 10.1016/j.physbeh.2022.113877 -
Nutrients Sep 2017Recently, some studies have focused on the relationship between dietary protein intake and the risk of type 2 diabetes mellitus (T2DM), but the conclusions have been... (Meta-Analysis)
Meta-Analysis Review
Recently, some studies have focused on the relationship between dietary protein intake and the risk of type 2 diabetes mellitus (T2DM), but the conclusions have been inconsistent. Therefore, in this paper, a systematic review and meta-analysis of cohort studies regarding protein consumption and T2DM risk are conducted in order to present the association between them. We searched the PubMed and Embase databases for cohort studies on dietary protein, high-protein food consumption and risk of T2DM, up to July 2017. A summary of relative risks was compiled by the fixed-effect model or random-effect model. Eleven cohort studies regarded protein intake and T2DM (52,637 cases among 483,174 participants). The summary RR and 95% CI (Confidence Interval) of T2DM was 1.12 (1.08-1.17) in all subjects, 1.13 (1.04-1.24) in men, and 1.09 (1.04-1.15) in women for total protein;1.14 (1.09-1.19) in all subjects, 1.23 (1.09-1.38) in men, and 1.11 (1.03-1.19) in women for animal protein; 0.96 (0.88-1.06) in all subjects, 0.98 (0.72-1.34) in men, and 0.92 (0.86-0.98) in women for plant protein. We also compared the association between different food sources of protein and the risk of T2DM. The summary RR (Relative Risk) and 95% CI of T2DM was 1.22 (1.09-1.36) for red meat, 1.39 (1.29-1.49) for processed meat, 1.03 (0.89-1.17) for fish, 1.03 (0.64-1.67) for egg, 0.89 (0.84-0.94) for total dairy products, 0.87 (0.78-0.96) for whole milk, 0.83 (0.70-0.98) for yogurt, 0.74 (0.59-0.93) in women for soy. This meta-analysis shows that total protein and animal protein could increase the risk of T2DM in both males and females, and plant protein decreases the risk of T2DM in females. The association between high-protein food types and T2DM are also different. Red meat and processed meat are risk factors of T2DM, and soy, dairy and dairy products are the protective factors of T2DM. Egg and fish intake are not associated with a decreased risk of T2DM. This research indicates the type of dietary protein and food sources of protein that should be considered for the prevention of diabetes.
Topics: Diabetes Mellitus, Type 2; Dietary Proteins; Female; Humans; Linear Models; Male; Odds Ratio; Protective Factors; Risk Assessment; Risk Factors
PubMed: 28878172
DOI: 10.3390/nu9090982 -
Advances in Nutrition (Bethesda, Md.) Sep 2014Sarcopenia is characterized by decreases in both muscle mass and muscle function. The loss of muscle mass, which can precede decrements in muscle function, is ultimately... (Review)
Review
Sarcopenia is characterized by decreases in both muscle mass and muscle function. The loss of muscle mass, which can precede decrements in muscle function, is ultimately rooted in an imbalance between the rates of muscle protein synthesis and breakdown that favors a net negative balance (i.e., synthesis < breakdown). A preponderance of evidence highlights a blunted muscle protein synthetic response to dietary protein, commonly referred to as “anabolic resistance,” as a major underlying cause of the insipid loss of muscle with age. Dietary strategies to overcome this decreased dietary amino acid sensitivity include the ingestion of leucine-enriched, rapidly digested proteins and/or greater protein ingestion in each main meal to maximally stimulate muscle anabolism. Anabolic resistance is also a hallmark of a sedentary lifestyle at any age. Given that older adults may be more likely to experience periods of reduced activity (either voluntarily or through acute illness), it is proposed that inactivity is the precipitating factor in the development of anabolic resistance and the subsequent progression from healthy aging to frailty. However, even acute bouts of activity can restore the sensitivity of older muscle to dietary protein. Provided physical activity is incorporated into the daily routine, muscle in older adults should retain its capacity for a robust anabolic response to dietary protein comparable to that in their younger peers. Therefore, through its ability to “make nutrition better,” physical activity should be viewed as a vital component to maintaining muscle mass and function with age.
Topics: Aging; Amino Acids; Dietary Proteins; Energy Intake; Humans; Leucine; Micronutrients; Motor Activity; Muscle Proteins; Muscle, Skeletal; Nutritional Requirements; Nutritional Status; Sarcopenia; Sedentary Behavior
PubMed: 25469405
DOI: 10.3945/an.113.005405