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The Cochrane Database of Systematic... Jan 2022Debates on effective and safe diets for managing obesity in adults are ongoing. Low-carbohydrate weight-reducing diets (also known as 'low-carb diets') continue to be... (Review)
Review
BACKGROUND
Debates on effective and safe diets for managing obesity in adults are ongoing. Low-carbohydrate weight-reducing diets (also known as 'low-carb diets') continue to be widely promoted, marketed and commercialised as being more effective for weight loss, and healthier, than 'balanced'-carbohydrate weight-reducing diets.
OBJECTIVES
To compare the effects of low-carbohydrate weight-reducing diets to weight-reducing diets with balanced ranges of carbohydrates, in relation to changes in weight and cardiovascular risk, in overweight and obese adults without and with type 2 diabetes mellitus (T2DM).
SEARCH METHODS
We searched MEDLINE (PubMed), Embase (Ovid), the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science Core Collection (Clarivate Analytics), ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) up to 25 June 2021, and screened reference lists of included trials and relevant systematic reviews. Language or publication restrictions were not applied.
SELECTION CRITERIA
We included randomised controlled trials (RCTs) in adults (18 years+) who were overweight or living with obesity, without or with T2DM, and without or with cardiovascular conditions or risk factors. Trials had to compare low-carbohydrate weight-reducing diets to balanced-carbohydrate (45% to 65% of total energy (TE)) weight-reducing diets, have a weight-reducing phase of 2 weeks or longer and be explicitly implemented for the primary purpose of reducing weight, with or without advice to restrict energy intake. DATA COLLECTION AND ANALYSIS: Two review authors independently screened titles and abstracts and full-text articles to determine eligibility; and independently extracted data, assessed risk of bias using RoB 2 and assessed the certainty of the evidence using GRADE. We stratified analyses by participants without and with T2DM, and by diets with weight-reducing phases only and those with weight-reducing phases followed by weight-maintenance phases. Primary outcomes were change in body weight (kg) and the number of participants per group with weight loss of at least 5%, assessed at short- (three months to < 12 months) and long-term (≥ 12 months) follow-up.
MAIN RESULTS
We included 61 parallel-arm RCTs that randomised 6925 participants to either low-carbohydrate or balanced-carbohydrate weight-reducing diets. All trials were conducted in high-income countries except for one in China. Most participants (n = 5118 randomised) did not have T2DM. Mean baseline weight across trials was 95 kg (range 66 to 132 kg). Participants with T2DM were older (mean 57 years, range 50 to 65) than those without T2DM (mean 45 years, range 22 to 62). Most trials included men and women (42/61; 3/19 men only; 16/19 women only), and people without baseline cardiovascular conditions, risk factors or events (36/61). Mean baseline diastolic blood pressure (DBP) and low-density lipoprotein (LDL) cholesterol across trials were within normal ranges. The longest weight-reducing phase of diets was two years in participants without and with T2DM. Evidence from studies with weight-reducing phases followed by weight-maintenance phases was limited. Most trials investigated low-carbohydrate diets (> 50 g to 150 g per day or < 45% of TE; n = 42), followed by very low (≤ 50 g per day or < 10% of TE; n = 14), and then incremental increases from very low to low (n = 5). The most common diets compared were low-carbohydrate, balanced-fat (20 to 35% of TE) and high-protein (> 20% of TE) treatment diets versus control diets balanced for the three macronutrients (24/61). In most trials (45/61) the energy prescription or approach used to restrict energy intake was similar in both groups. We assessed the overall risk of bias of outcomes across trials as predominantly high, mostly from bias due to missing outcome data. Using GRADE, we assessed the certainty of evidence as moderate to very low across outcomes. Participants without and with T2DM lost weight when following weight-reducing phases of both diets at the short (range: 12.2 to 0.33 kg) and long term (range: 13.1 to 1.7 kg). In overweight and obese participants without T2DM: low-carbohydrate weight-reducing diets compared to balanced-carbohydrate weight-reducing diets (weight-reducing phases only) probably result in little to no difference in change in body weight over three to 8.5 months (mean difference (MD) -1.07 kg, (95% confidence interval (CI) -1.55 to -0.59, I = 51%, 3286 participants, 37 RCTs, moderate-certainty evidence) and over one to two years (MD -0.93 kg, 95% CI -1.81 to -0.04, I = 40%, 1805 participants, 14 RCTs, moderate-certainty evidence); as well as change in DBP and LDL cholesterol over one to two years. The evidence is very uncertain about whether there is a difference in the number of participants per group with weight loss of at least 5% at one year (risk ratio (RR) 1.11, 95% CI 0.94 to 1.31, I = 17%, 137 participants, 2 RCTs, very low-certainty evidence). In overweight and obese participants with T2DM: low-carbohydrate weight-reducing diets compared to balanced-carbohydrate weight-reducing diets (weight-reducing phases only) probably result in little to no difference in change in body weight over three to six months (MD -1.26 kg, 95% CI -2.44 to -0.09, I= 47%, 1114 participants, 14 RCTs, moderate-certainty evidence) and over one to two years (MD -0.33 kg, 95% CI -2.13 to 1.46, I= 10%, 813 participants, 7 RCTs, moderate-certainty evidence); as well in change in DBP, HbA1c and LDL cholesterol over 1 to 2 years. The evidence is very uncertain about whether there is a difference in the number of participants per group with weight loss of at least 5% at one to two years (RR 0.90, 95% CI 0.68 to 1.20, I = 0%, 106 participants, 2 RCTs, very low-certainty evidence). Evidence on participant-reported adverse effects was limited, and we could not draw any conclusions about these. AUTHORS' CONCLUSIONS: There is probably little to no difference in weight reduction and changes in cardiovascular risk factors up to two years' follow-up, when overweight and obese participants without and with T2DM are randomised to either low-carbohydrate or balanced-carbohydrate weight-reducing diets.
Topics: Adult; Body Weight; Carbohydrates; Diet, Carbohydrate-Restricted; Energy Intake; Female; Heart Disease Risk Factors; Humans; Male
PubMed: 35088407
DOI: 10.1002/14651858.CD013334.pub2 -
Clinical Gastroenterology and... Jun 2023The association of nonalcoholic fatty liver disease (NAFLD) with dietary factors is well established but not thoroughly investigated. This systematic review and... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND & AIMS
The association of nonalcoholic fatty liver disease (NAFLD) with dietary factors is well established but not thoroughly investigated. This systematic review and meta-analysis synthesizes available evidence regarding the effect of nutrition on the presence and severity of NAFLD.
METHODS
A literature search was conducted identifying studies published between January 1985 and May 2021. We included studies with a dietary assessment and anthropometry based on validated tools, performed by a qualified dietitian or a trained health professional. We examined differences between patients with NAFLD and healthy controls as well as patients with NAFLD and nonalcoholic steatohepatitis (NASH). Risk of bias was assessed with the Risk Of Bias In Non-randomised Studies of Interventions (ROBINS-I) tool.
RESULTS
There were 60 eligible studies with 100,621 patients. The risk of bias was moderate for the majority of studies (41/60; 68%). According to meta-analyses, total caloric intake was higher in patients with NAFLD compared with controls (mean difference, 78.08; 95% confidence interval, 41.03-115.13). Macronutrient (protein, fat, and carbohydrate) consumption as proportion of total caloric intake and daily intake of fiber, caffeine and vitamins E, A, and C did not significantly differ between patients with NAFLD and controls. Soft drink consumption had a trend towards association with the presence of NAFLD. However, the odds ratio was 4.4 and the confidence intervals very wide. Finally, there was no significant difference in any comparison between patients with NAFLD and NASH, although the number of patients was relatively small. All meta-analyses had significant heterogeneity.
CONCLUSIONS
Overall, despite high heterogeneity among studies, this meta-analysis demonstrated that higher caloric intake is positively associated with NAFLD, whereas diet composition in macronutrients was not associated with the presence or severity of the disease.
Topics: Humans; Non-alcoholic Fatty Liver Disease; Diet; Energy Intake
PubMed: 34838723
DOI: 10.1016/j.cgh.2021.11.026 -
Journal of Renal Nutrition : the... Jan 2021Bone and mineral metabolism becomes dysregulated with progression of chronic kidney disease (CKD), and increasing levels of parathyroid hormone serve as an adaptive...
Bone and mineral metabolism becomes dysregulated with progression of chronic kidney disease (CKD), and increasing levels of parathyroid hormone serve as an adaptive response to maintain normal phosphorus and calcium levels. In end-stage renal disease, this response becomes maladaptive and high levels of phosphorus may occur. We summarize strategies to control hyperphosphatemia based on a systematic literature review of clinical trial and real-world observational data on phosphorus control in hemodialysis patients with CKD-mineral bone disorder (CKD-MBD). These studies suggest that current management options (diet and lifestyle changes; regular dialysis treatment; and use of phosphate binders, vitamin D, calcimimetics) have their own benefits and limitations with variable clinical outcomes. A more integrated approach to phosphorus control in dialysis patients may be necessary, incorporating measurement of multiple biomarkers of CKD-MBD pathophysiology (calcium, phosphorus, and parathyroid hormone) and correlation between diet adjustments and CKD-MBD drugs, which may facilitate improved patient management.
Topics: Calcimimetic Agents; Chelating Agents; Diet; Humans; Hyperphosphatemia; Kidney Failure, Chronic; Vitamin D
PubMed: 32386937
DOI: 10.1053/j.jrn.2020.02.003 -
Nutrients Jun 2023Previously, narrative reviews have considered the effects of intermittent fasting on appetite. One suggestion is that intermittent fasting attenuates an increase in... (Meta-Analysis)
Meta-Analysis Review
Previously, narrative reviews have considered the effects of intermittent fasting on appetite. One suggestion is that intermittent fasting attenuates an increase in appetite that typically accompanies weight loss. Here, we conducted the first systematic review and meta-analysis to quantify the effects of intermittent fasting on appetite, when compared to a continuous energy restriction intervention. Five electronic databases and trial registers were searched in February 2021 and February 2022. Abstracts (N = 2800) were screened and 17 randomized controlled trials (RCTs), consisting of a variety of intermittent fasting regimes, met our inclusion criteria. The total number of participants allocated to interventions was 1111 and all RCTs were judged as having either some concerns or a high risk of bias (Cochrane RoB 2.0 tool). Random effects meta-analyses were conducted on change-from-baseline appetite ratings. There was no clear evidence that intermittent fasting affected hunger (WMD = -3.03; 95% CI [-8.13, 2.08]; = 0.25; N = 13), fullness (WMD = 3.11; 95% CI [-1.46, 7.69]; = 0.18; N = 10), desire to eat (WMD = -3.89; 95% CI [-12.62, 4.83]; = 0.38; N = 6), or prospective food consumption (WMD = -2.82; 95% CI [-3.87, 9.03]; = 0.43; N = 5), differently to continuous energy restriction interventions. Our results suggest that intermittent fasting does not mitigate an increase in our drive to eat that is often associated with continuous energy restriction.
Topics: Humans; Appetite; Intermittent Fasting; Energy Intake; Hunger; Weight Loss; Fasting
PubMed: 37299567
DOI: 10.3390/nu15112604 -
European Heart Journal Jul 2023Due to growing environmental focus, plant-based diets are increasing steadily in popularity. Uncovering the effect on well-established risk factors for cardiovascular... (Meta-Analysis)
Meta-Analysis
AIMS
Due to growing environmental focus, plant-based diets are increasing steadily in popularity. Uncovering the effect on well-established risk factors for cardiovascular diseases, the leading cause of death worldwide, is thus highly relevant. Therefore, a systematic review and meta-analysis were conducted to estimate the effect of vegetarian and vegan diets on blood levels of total cholesterol, low-density lipoprotein cholesterol, triglycerides, and apolipoprotein B.
METHODS AND RESULTS
Studies published between 1980 and October 2022 were searched for using PubMed, Embase, and references of previous reviews. Included studies were randomized controlled trials that quantified the effect of vegetarian or vegan diets vs. an omnivorous diet on blood lipids and lipoprotein levels in adults over 18 years. Estimates were calculated using a random-effects model. Thirty trials were included in the study. Compared with the omnivorous group, the plant-based diets reduced total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B levels with mean differences of -0.34 mmol/L (95% confidence interval, -0.44, -0.23; P = 1 × 10-9), -0.30 mmol/L (-0.40, -0.19; P = 4 × 10-8), and -12.92 mg/dL (-22.63, -3.20; P = 0.01), respectively. The effect sizes were similar across age, continent, duration of study, health status, intervention diet, intervention program, and study design. No significant difference was observed for triglyceride levels.
CONCLUSION
Vegetarian and vegan diets were associated with reduced concentrations of total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B-effects that were consistent across various study and participant characteristics. Plant-based diets have the potential to lessen the atherosclerotic burden from atherogenic lipoproteins and thereby reduce the risk of cardiovascular disease.
Topics: Adult; Humans; Diet, Vegan; Diet, Vegetarian; Randomized Controlled Trials as Topic; Lipids; Vegetarians; Cholesterol, LDL; Lipoproteins; Cardiovascular Diseases; Atherosclerosis; Apolipoproteins
PubMed: 37226630
DOI: 10.1093/eurheartj/ehad211 -
Nutrients Aug 2022During the complementary feeding period, any nutritional deficiencies may negatively impact infant growth and neurodevelopment. A healthy diet containing all essential... (Review)
Review
During the complementary feeding period, any nutritional deficiencies may negatively impact infant growth and neurodevelopment. A healthy diet containing all essential nutrients is strongly recommended by the WHO during infancy. Because vegetarian diets are becoming increasingly popular in many industrialized countries, some parents ask the pediatrician for a vegetarian diet, partially or entirely free of animal-source foods, for their children from an early age. This systematic review aims to evaluate the evidence on how vegetarian complementary feeding impacts infant growth, neurodevelopment, risk of wasted and/or stunted growth, overweight and obesity. The SR was registered with PROSPERO 2021 (CRD 42021273592). A comprehensive search strategy was adopted to search and find all relevant studies. For ethical reasons, there are no interventional studies assessing the impact of non-supplemented vegetarian/vegan diets on the physical and neurocognitive development of children, but there are numerous studies that have analyzed the effects of dietary deficiencies on individual nutrients. Based on current evidence, vegetarian and vegan diets during the complementary feeding period have not been shown to be safe, and the current best evidence suggests that the risk of critical micronutrient deficiencies or insufficiencies and growth retardation is high: they may result in significantly different outcomes in neuropsychological development and growth when compared with a healthy omnivorous diet such as the Mediterranean Diet. There are also no data documenting the protective effect of vegetarian or vegan diets against communicable diseases in children aged 6 months to 2-3 years.
Topics: Animals; Diet, Vegan; Diet, Vegetarian; Eating; Humans; Infant; Infant Nutritional Physiological Phenomena; Malnutrition; Vegetarians
PubMed: 36079848
DOI: 10.3390/nu14173591 -
International Journal of Environmental... Sep 2022(1) Background: Recently, studies have emerged to explore the effects of concurrent training (CT) with a low-carb, high-fat ketogenic diet (LCHF) on body composition and... (Meta-Analysis)
Meta-Analysis Review
The Effects of Concurrent Training Combined with Low-Carbohydrate High-Fat Ketogenic Diet on Body Composition and Aerobic Performance: A Systematic Review and Meta-Analysis.
(1) Background: Recently, studies have emerged to explore the effects of concurrent training (CT) with a low-carb, high-fat ketogenic diet (LCHF) on body composition and aerobic performance and observed its benefits. However, a large variance in the study design and observations is presented, which needs to be comprehensively assessed. We here thus completed a systematic review and meta-analysis to characterize the effects of the intervention combining CT and LCHF on body composition and aerobic capacity in people with training experience as compared to that combining CT and other dietary strategies. (2) Methods: A search strategy based on the PICOS principle was used to find literature in the databases of PubMed, Web of Science, EBSCO, Sport-discuss, and Medline. The quality and risk of bias in the studies were independently assessed by two researchers. (3) Result: Eight studies consisting of 170 participants were included in this work. The pooled results showed no significant effects of CT with LCHF on lean mass (SMD = -0.08, 95% CI -0.44 to 0.3, = 0.69), body fat percentage (SMD = -0.29, 95% CI -0.66 to 0.08, = 0.13), body mass (SMD = -0.21, 95% CI -0.53 to 0.11, = 0.2), VO (SMD = -0.01, 95% CI -0.4 to 0.37, = 0.95), and time (or distance) to complete the aerobic tests (SMD = -0.02, 95% CI -0.41 to 0.37, = 0.1). Subgroup analyses also showed that the training background of participants (i.e., recreationally trained participants or professionally trained participants) and intervention duration (e.g., > or ≤six weeks) did not significantly affect the results. (4) Conclusions: This systematic review and meta-analysis provide evidence that compared to other dietary strategies, using LCHF with CT cannot induce greater benefits for lean mass, body fat percentage, body mass, VO, and aerobic performance in trained participants.
Topics: Body Composition; Carbohydrates; Diet, High-Fat; Diet, Ketogenic; Exercise Tolerance; Humans
PubMed: 36141816
DOI: 10.3390/ijerph191811542 -
Nutrition Research (New York, N.Y.) Nov 2021Several studies have associated the food processing classification - NOVA - and health, but this is not true for all noncommunicable chronic diseases (NCDs). This study... (Review)
Review
Several studies have associated the food processing classification - NOVA - and health, but this is not true for all noncommunicable chronic diseases (NCDs). This study aimed to systematically review the association between the intake of NOVA food groups and NCDs. We hypothesized that ultra-processed foods and drinks (UPFD) and processed foods (PF) could increase the risk of NCDs, and that unprocessed (UPF) and minimally processed foods (MPF) may provide protection. We carried out a systematic review of observational studies in January 2021. Searches were performed in SCOPUS, MEDLINE (via PubMed), EMBASE, WEB OF SCIENCE, SCIELO, related articles, hand-searching of reference lists, and direct author contact. In all, 2217 citations were identified and 38 articles met the eligibility criteria for inclusion in this systematic review. Among the analyzed food groups, higher UPFD consumption was positively associated with obesity and associated with the development of all NCDs, mainly hypertension, diabetes and dyslipidemia. However, only a few studies have demonstrated the protective effect of natural foods and MPF consumption on the occurrence of NCDs. In conclusion, UPF may increase the risk of NCDs, and natural foods and MPF may reduce it. Our results reinforce the need for the implementation of policies to mitigate the intake of UPF by the population, as it would improve the quality of the dietary patterns, and directly impact on the incidence of NCDs.
Topics: Chronic Disease; Diet; Energy Intake; Fast Foods; Food Handling; Humans; Noncommunicable Diseases
PubMed: 34798466
DOI: 10.1016/j.nutres.2021.08.006 -
Journal of the Academy of Nutrition and... Apr 2021Stimuli that promote eating in the absence of the physiological need for food are pervasive and can facilitate excessive energy intake. The practices of mindful eating...
BACKGROUND
Stimuli that promote eating in the absence of the physiological need for food are pervasive and can facilitate excessive energy intake. The practices of mindful eating (ME) and intuitive eating (IE) have been developed to minimize external drivers of energy intake by helping individuals emphasize the sensory properties of foods and internal indicators of hunger and fullness.
OBJECTIVE
To enhance understanding about the effect of ME and IE interventions on dietary intake, this systematic review included randomized trials of ME and IE interventions that examined dietary intake, defined as energy intake or diet quality, in adults of varying weight status without a diagnosis of an eating disorder.
METHODS
The selection of literature followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic review process, in which PubMed, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and PsycINFO databases were searched for studies published between January 1980 and November 2019. Studies were included if they met the following criteria: randomized trial design in which 1 arm was an intervention with an ME or IE component and there was at least 1 control or active comparison arm; enrolled participants were of a healthy weight or with overweight or obesity and reported not having an eating disorder (ie, anorexia, bulimia nervosa, or binge eating disorder) or other health conditions in which dietary restrictions were applied; were at least 18 years of age; and outcomes of energy intake or diet quality were reported at baseline and post intervention. The modified Downs and Black checklist was used to assess risk of bias for each study that met inclusion criteria.
RESULTS
A total of 13 studies, including 8 investigating ME interventions and 5 investigating IE interventions, represented in 14 articles, were included in the review. Seven of the 9 articles reporting on energy intake did not find significant group differences. Eight of the 12 articles reporting on diet quality did not find significant group differences. The mean bias assessment score was 13.6 out of 28, indicating poor quality.
CONCLUSIONS
Little evidence suggests that ME and IE interventions influence energy intake or diet quality. To draw strong conclusions about the effect of ME and IE on dietary intake, future research using study designs of high rigor are needed.
Topics: Diet; Eating; Energy Intake; Female; Humans; Male; Mindfulness; Randomized Controlled Trials as Topic
PubMed: 33279464
DOI: 10.1016/j.jand.2020.10.019 -
Nutrients Jul 2021The human gut microbiota are the microorganisms (generally bacteria and archaea) that live in the digestive tracts of humans. Due to their numerous functions, the gut...
The human gut microbiota are the microorganisms (generally bacteria and archaea) that live in the digestive tracts of humans. Due to their numerous functions, the gut microbiota can be considered a virtual organ of the body, playing a pivotal role in health maintenance. Dietary habits contribute to gut microbiota composition, and evidence from observational and intervention studies suggest that vegan diets may promote health, potentially through affecting the diverse ecosystem of beneficial bacteria in the gut. A systematic literature search was conducted on PubMed and Scopus to identify studies investigating the microbiota composition in vegans. Vegans are defined as people excluding food products that are derived from animals from their diet. Nine observational studies were identified. The main outcome of the systematic review was an increase in Bacteroidetes on the phylum level and a higher abundance of on the genus level. In conclusion, the present systematic literature review highlighted some benefits of a vegan diet but also demonstrated the complexity of evaluating results from gut microbiota research. The available evidence only consisted of cross-sectional studies, therefore suggesting the need for well-designed randomised controlled trials. Furthermore, the quality assessment of the studies included in the review suggested a lack of standardised and validated methods for participant selection as well as for faecal sampling and faecal analysis.
Topics: Adult; Bacteria; Diet, Healthy; Diet, Vegan; Dysbiosis; Feces; Female; Gastrointestinal Microbiome; Humans; Intestines; Male; Middle Aged; Nutritive Value
PubMed: 34371912
DOI: 10.3390/nu13072402