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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 -
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 -
Effects of dietary protein on gut development, microbial compositions and mucin expressions in mice.Journal of Applied Microbiology Mar 2022Dietary protein, as an important macronutrient, widely participates in host growth and metabolism. In this study, effects of different protein levels (14, 20 and 26%) on...
AIMS
Dietary protein, as an important macronutrient, widely participates in host growth and metabolism. In this study, effects of different protein levels (14, 20 and 26%) on the gut development, microbial compositions and mucin expressions were studied in C57BL/6 mice.
METHODS AND RESULTS
The results showed that body weight and the relative weight of stomach and gut were decreased in low-protein diet-fed mice, whereas high-protein diet significantly reduced the villus length and area of jejunum. Goblet cells number in the jejunum was reduced in the low-protein group, which was reversed by dietary a high-protein diet. In addition, high-protein diet notably reduced microbial diversity and changed the microbial compositions at the phylum level, such as Bacteroides, Proteobacteria, Actinomycetes and Deferribacteres. Furthermore, high-protein diet significantly increased mucin2, mucin3 and mucin4 expressions in the jejunum, but downregulated mucin1, mucin2, mucin4 and TFF3 in the ileum, indicating a tissue-dependent manner.
CONCLUSIONS
Together, high-protein diet may impair gut development, microbial balance and mucin system, and a low-protein diet is suggested to promote a healthy lifestyle.
SIGNIFICANCE AND IMPACT OF STUDY
Mucin influenced gut development (villus index and goblet cell number) through remodelling gut microbes, as low and high protein levels resulted in contrary expression levels of mucin in jejunum and ileum.
Topics: Animals; Diet; Dietary Proteins; Ileum; Mice; Mice, Inbred C57BL; Mucins
PubMed: 34411380
DOI: 10.1111/jam.15260 -
Advances in Experimental Medicine and... 2020Dietary protein digestion is an efficient process resulting in the absorption of amino acids by epithelial cells, mainly in the jejunum. Some amino acids are extensively... (Review)
Review
Dietary protein digestion is an efficient process resulting in the absorption of amino acids by epithelial cells, mainly in the jejunum. Some amino acids are extensively metabolized in enterocytes supporting their high energy demand and/or production of bioactive metabolites such as glutathione or nitric oxide. In contrast, other amino acids are mainly used as building blocks for the intense protein synthesis associated with the rapid epithelium renewal and mucin production. Several amino acids have been shown to support the intestinal barrier function and the intestinal endocrine function. In addition, amino acids are metabolized by the gut microbiota that use them for their own protein synthesis and in catabolic pathways releasing in the intestinal lumen numerous metabolites such as ammonia, hydrogen sulfide, branched-chain amino acids, polyamines, phenolic and indolic compounds. Some of them (e.g. hydrogen sulfide) disrupts epithelial energy metabolism and may participate in mucosal inflammation when present in excess, while others (e.g. indole derivatives) prevent gut barrier dysfunction or regulate enteroendocrine functions. Lastly, some recent data suggest that dietary amino acids might regulate the composition of the gut microbiota, but the relevance for the intestinal health remains to be determined. In summary, amino acid utilization by epithelial cells or by intestinal bacteria appears to play a pivotal regulator role for intestinal homeostasis. Thus, adequate dietary supply of amino acids represents a key determinant of gut health and functions.
Topics: Amino Acids; Dietary Proteins; Gastrointestinal Microbiome; Health; Humans; Intestines
PubMed: 32761567
DOI: 10.1007/978-3-030-45328-2_1 -
Clinical Science (London, England :... Feb 2020Obesity and increased body adiposity have been alarmingly increasing over the past decades and have been linked to a rise in food intake. Many dietary restrictive... (Review)
Review
Obesity and increased body adiposity have been alarmingly increasing over the past decades and have been linked to a rise in food intake. Many dietary restrictive approaches aiming at reducing weight have resulted in contradictory results. Additionally, some policies to reduce sugar or fat intake were not able to decrease the surge of obesity. This suggests that food intake is controlled by a physiological mechanism and that any behavioural change only leads to a short-term success. Several hypotheses have been postulated, and many of them have been rejected due to some limitations and exceptions. The present review aims at presenting a new theory behind the regulation of energy intake, therefore providing an eye-opening field for energy balance and a potential strategy for obesity management.
Topics: Adiposity; Dietary Proteins; Energy Metabolism; Humans; Models, Biological; Nutrients; Obesity
PubMed: 32064496
DOI: 10.1042/CS20190583 -
The American Journal of Medicine Feb 2020Animal and vegetable-based proteins differ on their effect on many health outcomes, but their relationship with unhealthy aging is uncertain. Thus, we examined the...
BACKGROUND
Animal and vegetable-based proteins differ on their effect on many health outcomes, but their relationship with unhealthy aging is uncertain. Thus, we examined the association between changes in animal and vegetable protein intake and unhealthy aging in older adults.
METHODS
Data came from 1951 individuals aged ≥60 years recruited in the Seniors-ENRICA cohort in 2008-2010 (wave 0) and followed-up in 2012 (wave 1), 2015 (wave 2), and 2017 (wave 3). Dietary protein intake was measured with a validated diet history at waves 0 and 1, and unhealthy aging was measured with a 52-item health deficit accumulation index at each wave.
RESULTS
Compared with participants with a >2% decrease in energy intake from vegetable protein from wave 0 to wave 1, those with a >2% increase showed less deficit accumulation over 3.2 years (multivariable β [95% confidence interval (CI)]: -1.05 [-2.03, -0.06]), 6 years (-1.28 [-2.51, -0.03]), and 8.2 years of follow-up (-1.68 [-3.27, -0.09]). No associations were found for animal protein. Less deficit accumulation over 8.2 years was observed when substituting 1% of energy from vegetable protein for an equal amount of carbohydrate or fat (-0.50 [-0.93, -0.07]), animal protein (-0.44 [-0.81, -0.07]), dairy protein (-0.51 [-0.91, -0.12]), or meat protein (-0.44 [-0.84, -0.04]).
CONCLUSIONS
Increasing dietary intake of vegetable protein may delay unhealthy aging when replacing carbohydrates, fats, or animal protein, especially from meat and dairy.
Topics: Animals; Dairy Products; Dietary Proteins; Energy Intake; Female; Healthy Aging; Humans; Male; Meat; Middle Aged; Plant Proteins
PubMed: 31369726
DOI: 10.1016/j.amjmed.2019.06.051 -
Nutrition Research Reviews Dec 2023The rates of dietary protein digestion and absorption can be significantly increased or decreased by food processing treatments such as heating, gelling and enzymatic... (Review)
Review
The rates of dietary protein digestion and absorption can be significantly increased or decreased by food processing treatments such as heating, gelling and enzymatic hydrolysis, with subsequent metabolic impacts, e.g. on muscle synthesis and glucose homeostasis.This review examines evidence that industrial and domestic food processing modify the kinetics of amino acid release and absorption following a protein-rich meal. It focuses on studies that used compositionally-matched test meals processed in different ways.Food processing at extremely high temperature at alkaline pH and/or in the presence of reducing sugars can modify amino acid sidechains, leading to loss of bioavailability. Some protein-rich food ingredients are deliberately aggregated, gelled or hydrolysed during manufacture. Hydrolysis accelerates protein digestion/absorption and increases splanchnic utilisation. Aggregation and gelation may slow or accelerate proteolysis in the gut, depending on the aggregate/gel microstructure.Milk, beef and eggs are heat processed prior to consumption to eliminate pathogens and improve palatability. The temperature and time of heating affect protein digestion and absorption rates, and effects are sometimes non-linear. In light of a dietary transition away from animal proteins, more research is needed on how food processing affects digestion and absorption of non-animal proteins.Food processing modifies the microstructure of protein-rich foods, and thereby alters protein digestion and absorption kinetics in the stomach and small intestine. Exploiting this principle to optimise metabolic outcomes requires more human clinical trials in which amino acid absorption rates are measured and food microstructure is explicitly considered, measured and manipulated.
Topics: Animals; Cattle; Humans; Proteolysis; Digestion; Amino Acids; Dietary Proteins; Food Handling
PubMed: 36522674
DOI: 10.1017/S0954422422000245 -
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 -
Current Opinion in Clinical Nutrition... Jan 2021
Topics: Amines; Amino Acids; Dietary Proteins; Humans
PubMed: 33323716
DOI: 10.1097/MCO.0000000000000702 -
Current Opinion in Clinical Nutrition... Jan 2018The speed of dietary protein digestion influences postprandial amino acid availability which is crucial for improving altered anabolic response of skeletal muscle one... (Review)
Review
PURPOSE OF REVIEW
The speed of dietary protein digestion influences postprandial amino acid availability which is crucial for improving altered anabolic response of skeletal muscle one feature of sarcopenia during aging.
RECENT FINDINGS
By analogy with carbohydrate and in reference to their absorption rate, dietary proteins can be classified as 'fast' or 'slow' proteins depending on matrix food structure and technological processes, which can influence amino acids availability and their subsequent metabolic actions. 'Fast' digestive proteins have been shown to stimulate muscle protein synthesis and to improve muscle function in several recent studies involving older patients. These new aspects may be applied for improving health through preservation or restoration of muscle protein mass and function in clinical situations (obesity, rheumatoid arthritis and cancer cachexia).
SUMMARY
Using fast digestive proteins is of major interest to overcome 'anabolic resistance' of aging for limiting sarcopenia. Fast proteins' action on muscle anabolism may be stimulated by other nutrients like vitamin D or omega 3 fatty acids or by combination with exercise. The beneficial impact of the 'fast' protein concept beyond the amount of dietary protein on muscle preservation is a promising therapeutic perspective to improve mobility and quality of life of older patients affected with chronic disease.
Topics: Aged; Aged, 80 and over; Aging; Amino Acids; Animals; Dietary Proteins; Dietary Supplements; Digestion; Elder Nutritional Physiological Phenomena; Humans; Intestinal Absorption; Kinetics; Muscle Proteins; Muscle, Skeletal; Postprandial Period; Sarcopenia
PubMed: 29028650
DOI: 10.1097/MCO.0000000000000427